에폭시 아크릴레이트를 이용한 감광성 폴리머 저항 페이스트 조성

photosensitive; thick film; resistor; epoxy acrylate oligomer; carbon black

Using six kinds of epoxy acrylates and a conductive carbon black, photosensitive resistor pastes were fabricated and then their developability in alkaline aqueous solution and the resistance values after thermal curing were evaluated. In order to impart the photocurability by UV exposure and the developability on alkaline solution, epoxy acrylate oligomers with carboxyl group, acrylate monomers, a photoinitiator and so forth were used. In addition, an organic peroxide was added into the paste to get a thermally curable composition. As a result, some of the pastes were not developed depending on the kinds of oligomers and, in the developed pastes, the measured resistance showed the different values depending on their compositions, even though they contain the same amount of carbon black. Finally, the optimum oligomer was selected and then, by adjusting the amount of carbon black, the kind of monomer and the curing temperature, the photosensitive resistor paste composition which showed the sheet resistance of about 0.5 kΩ/sq. could be obtained.

전기화학 반응에 의한 염화철 폐식각액의 재생 및 구리 회수에 관한 연구

Electrochemical regeneration; Iron chloride; Waste etchant; Copper recovery; Carbon electrode

Electrochemical regeneration of the iron chloride waste solution from PCB etching reduces environmental contamination and produces copper as by-product, so the economic feasibility is high. But iron chloride waste solution contains iron and copper and the reactions occurring in the electrolytic cell are complicated. In this work, the oxidation of iron chloride and copper deposition were examined through batch electrolysis and the optimum conditions of the process parameters were found. The oxidation of ferrous chloride was achieved easily to the desired level. The copper deposition efficiency was high in the reaction using the carbon cathode when the copper density was 12 g/L with the electric current density of 350 mA /cm2, and the ratio of the Fe2+ ion was high. In addition, the possibility of the scale-up was confirmed in continuous operation of bench reactor using the optimum conditions obtained.

Preparation of amino-functionalized silica for copper removal from an aqueous solution

Functionalized silica; Copper removal; Absorption

In the present research, amino-functionalized silica materials were synthesized to develop absorbents for removing copper (II) ions from water. Three kinds of silica with various BET surface areas and pore volumes (331.4 m2/g, 460.1 m2/g, 717.7 m2/g and 1.38 cm3/g, 1.06 cm3/g, 0.57 cm3/g, respectively) were used to determine an optimum material. 3-Aminopropyltrimethoxysilane (3-APTMS) and N-[3-(trimethoxysilyl)propyl]-ethylenediamine (MSDA) are two amino-functional moieties grafted onto silica surfaces. A maximum copper absorption of 33.45 mg/g was confirmed using the aminofunctionalized material at an initial 3-APTMS concentration of 2.52 mmol/g. Silica with a BET surface of 331 m2/g and a pore volume of 1.38 cm3/g demonstrated a good copper absorption capacity. Interference species such as pH, NH3 and EDTA were also studied in this work.

마이크로 중공구를 이용한 자외선 경화 코팅 박막의 단열 특성

Hollow Micro Sphere; Thermal Insulation Property; UV Curable Resin; Coated Glass

In this study, the composite coating materials with improved thermal insulation property were prepared by incorporating the hollow micro-spheres with high heat transfer resistance. The UV curable resin system consisting of hexa aliphatic urethane acrylate (UP118), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), and photoinitiator (Irgacure184) was employed as an organic binder. The glass substrates were coated by the prepared composites via bar coating method and cured under UV radiation. The optical transparency, thermal insulation property, adhesion, and surface hardness of the glass coated with composites containing different type of micro-spheres were investigated. The incorporation of micro-spheres with only 20 vol% of content resulted in remarkable improvement in the thermal insulation property of the coated glass. In addition, the transparent coated glass with light transmittance of about 80% could be obtained when silica micro-sphere (SP) was used as a thermal barrier.

UV 경화형 단량체계 실리카 분산체의 점도 특성 및 유변학적 거동

Photo Curable Acrylic Monomer; Silica; Silica Dispersion; Rheology; Solvation Effect

We made 8 wt% silica dispersion system with fumed silica and photo curable acrylic monomer by beads mill process. These dispersions could be applied in organic/inorganic hybrid coating systems. These dispersions could be applied in organic/inorganic hybrid coating systems. The 4 species of photo curable acrylic monomer which was presence of hydroxyl group, different solubility parameter, and different molecular size were used in the silica dispersions. Stability of polar solvent, isopropyl alcohol, in silica dispersions was investigated. We investigated the stability of silica dispersions by using steady-state and dynamic rheology. As the monomer has hydroxyl group increased in mono and binary monomer silica dispersions, they showed non flocculated stable sol (loss modulus (G'')> storage modulus (G')). When polar solvent IPA was added into slightly flocculated silica dispersions, they changed to non flocculated stable sol.

산-염기 표면처리된 MWNTs의 첨가가 탄소섬유 강화 복합재료의 기계적 계면특성에 미치는 영향

carbon composites; multi-walled carbon nanotubes; surface treatment; mechanical properties.

In this work, the effect of chemical treatments of multi-walled carbon nanotubes (MWNTs) on the mechanical interfacial properties of carbon fiber fabric-reinforced composites was investigated. The surface properties of the MWNTs were determined by acid and base values, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. The mechanical interfacial properties of the composites were assessed by interlaminar shear stress (ILSS) and critical stress intensity factor (KIC). The chemical treatments based on acid and base reactions led to a significant change of surface characteristics of the MWNTs, especially A-MWNTs/carbon fibers/epoxy composites had higher mechanical properties than those of B-MWNTs and non-treated MWNTs/carbon fibers/epoxy composites. These results were probably due to the improvement of interfacial bonding strength, resulting from the acid-base interaction and hydrogen bonding between the epoxy resins and the MWNT fillers.

다관능 우레탄 아크릴레이트 단량체의 합성과 분석, 및 폴리페닐렌에테르 기판소재용 경화성분으로의 적용

urethane acrylate; poly(phenylene ether); curing agent; dielectric properties; peel strength.

Multi-functional urethane acrylate monomers as the curing agent of poly(phenylene ether) (PPE) were synthesized and then the urethane bond formation was checked by FTIR spectrometry and NMR analysis. The synthesized monomers were mixed with PPE and fabricated to dielectric substrates. After forming PPE/monomer composite sheets by a film coater, several sheets were laminated to a test substrate in a vacuum laminator and then its properties depending on the type and the amount of monomers, such as dielectric constant, dielectric loss, and peel strength, were measured. Between the two different hydroxyl acrylates, when the monomer synthesized with 2-hydroxy-3-phenoxypropyl acrylate containing a phenyl group was used as a curing agent, a smaller dielectric loss was obtained and the dielectric constant and loss decreased with a decrease in the amount of the monomer. The peel strength values of the test substrates, however, did not show any specific difference between the cases of two synthesized monomers. As a result, it was obtained the polymer substrate for high frequency application having peel strength of about 10 N, low dielectric constant of 2.54, and low dielectric loss of 0.0027 at 1 GHz.

바이오에너지 및 바이오화학원료인 C4-C6 생산

biomaterials; bioenergy; butanol; n-butyric acid; n-hexanoic acid

Depletion of petroleum increased the need of alternative energy and chemical resources. Biomass, a renewable resource, can be transformed to bioenergy and biomaterials, and the materials from biomass will ultimately substitute petroleum based energy and chemical compounds. In this perspective, production of C4-C6 compounds for bioenergy and biomaterials are described for understating of current research progress. n-Butanol and n-butyric acid, the major C4 compounds, are produced by Clostridium tyrobutyricum, Clostridium beijerinckii, and Clostridium acetobutylicum. n-Hexanoic acid, a typical C6 compound, is produced by Clostridium kluyveri and Megasphaera elsdenii. Reported maximum amount of n-butanol, n-butyric acid and n-hexanoic acid was 21, 55, and 19 g/L, respectively, and extraction of these C4-C6 compounds are induced increase production by those anaerobic bacteria. In addition, a new bacterium Clostridium sp. BS-1 produced 5 g/L of n-hexanoic acid using galactitol.

폴리에틸렌 글리콜 내에서의 흄드 실리카 현탁액의 전단농화 거동연구

shear-thickening; fumed silica; polyethylene glycol; suspension

We made suspension of fumed silica in polyethylene glycol (PEG), studied rheological behavior as functions of contents of silica, dispersion condition, PEG molecular weight, temperature and contents of humidity. Rheological behavior of suspension was determined critical shear rate and rise of viscosity using rheometer AR2000. Suspension were PEGs of molecular weight 200, 400, and 600. Fumed silica suspensions of which silica contents are 5, 7, 9, 13, and 18% were prepared by normal mixing, homogenization and bead milling process. We observed their rheological behaviors at 10, 20, 30, and 40 ℃. As the PEG molecular weight and contents of silica increase, the critical shear rate was lowered. As the temperature increased, the critical shear rate was increased. Humidity contents of dispersion don’t influence on the critical shear rate, but dispersion processes greatly affect the critical shear rate. The critical shear rate of suspensions prepared by the mixing process was the lowest, and that of suspensions prepared by the bead milling process was the highest. The rise in the shear viscosity of suspensions prepared by the mixing process is higher than that of suspensions prepared by the bead milling process. This was dependent on the dispersion condition of silica particle by dispersion process.

Crosslinked poly(ethylene glycol) (PEG)/sulfonated polyhedral oligosilsesquioxane (sPOSS) hybrid membranes for direct methanol fuel cell applications

Hybrid membrane; Sulfonated polyhedral oligomeric; silsesquioxane (sPOSS); Direct methanol fuel cell (DMFC)

Organic.inorganic hybrid crosslinked membranes based on poly(ethylene glycol) (PEG) and sulfonated polyhedral oligomeric silsesquioxane (POSS-SO3H) with urethane crosslinks were prepared as candidate materials for a proton exchange membrane for direct methanol fuel cells (DMFC). Infrared (FT-IR) spectroscopy and ion exchange capacity measurements for the hybrid revealed the POSS is incorporated as a part of the crosslinked network. We found that proton conductivity increased and methanol permeability decreased with increasing POSS content in the hybrid membrane. In particular, our hybrid membranes demonstrated proton conductivities comparable to that of Nafion 117 while exhibiting lower methanol permeability as compared to Nafion 117. We postulate that the polar sulfonic acid groups of the incorporated sPOSS cages assemble to provide ion conduction paths while the hydrophobic portions of the same sPOSS cages combine to form a barrier to methanol permeation of the hybrid membrane.

Effect of heating rate on pyrolysis of low-grade pyrolytic oil

Municipal Plastic Waste; Pyrolysis; Low-grade Pyrolytic Oil; Upgrading; Heating Rate; Characteristic of Products

The low-grade pyrolytic oil produced from pyrolysis of municipal plastic waste in a commercial rotary kiln reaction system cannot be an acceptable fuel oil due to its low quality. Thus, the degradation of pyrolytic oil was conducted in a bench scale batch reactor, which was done by two experiment conditions of high heating rate (about 7℃ /min) and low heating rate (1.5-3.6 ℃/min) up to 420 ℃ of reaction temperature. The characteristics of raw pyrolytic oil were examined and also the characteristics of products obtained by different heating rates were compared. Raw pyrolytic oil had higher H/C ratio and higher heating value than commercial oils, and also its peak range in GC analysis showed wide distribution including all the range of gasoline, kerosene and diesel. In the upgrading of pyrolytic oil, cumulative amount profile of product oil, as a function of reaction time, was similar in shape to the degradation temperature profile. All product oils obtained by different degradation temperature had higher H/C ratio and slightly higher heating value than those of raw pyrolytic oil. Also, the characteristics of product oils were influenced by heating rate and reaction temperature.

Biomass 유래 퓨란계 단량체를 이용한 폴리에스터의 중합 및 특성 연구

biomass; polyester; FDCA; furan.

Furan-2,5-dicarboxylic acid (FDCA) was synthesized by KMnO4 oxidation of 2,5-dihydroxymethylfuran(DHMF) derived from biomass. Polyesters were synthesized by esterification and polycondensation of FDCA with various diols(ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol, hexane-1,6-diol, decane-1,10-diol). The composition of polyesters was characterized by using 1H NMR. Thermal properties of the polyesters were characterized by DSC and TGA. Intrinsic viscosities(IV) of the polyesters were measured to be 0.78∼1.2dL/g comparable with IV of commercial poly(ethylene terephthalate)(PET). As the chain lengths of diols increased, Young’s modulus and strength decreased and elongation-to-break generally increased. Young’s modulus and strength of the polyesters were measured to be 3551 MPa and 103 MPa, respectively, comparable with commercial PET.

3-Azidopropane-1,2-diol로 쇄연장된 GAP/PTMG 폴리우레탄의 상거동

polyurethane; energetic binder; viscoelastic behaviors; energetic chain extender

We perform a comparative study to investigate the properties of the new energetic chain extender (AzPD). A series of poly(glycidyl azide)/poly(tetramethylene oxide)-based energetic segmented polyurethane (GAP/PTMG ESPU) with different chain extender, which is 3-azidopropane-1,2-diol (AzPD), 1,4-butane diol (1,4-BD), or 1,5 pentane diol (1,5-PD), was synthesized by solution polymerization in dimethyl formamide (DMF) and their phase behaviors were investigated. The ESPUs were characterized with Fourier transform infrared-attenuated total reflection spectroscopy (ATR FT-IR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results of the ATR FT-IR analysis of the urethane carbonyl group region showed that the ‘free’ C=O fraction was higher in GAP/PTMG AzESPU (0.5) than GAP/PTMG BDESPU (0.44) and GAP/PTMG PDESPU (0.41) for 7 days samples after preparation and that it was similar in the range of 0.26∼0.29 for three 60 days ESPU samples. DMA curves of the GAP/PTMG AzESPU for 7 days samples showed amorphous polymers, but GAP/PTMG BDESPU and GAP/PTMG PDESPU showed viscoelastic behaviors with rubbery plateau and the flow region. However, DMA curves of the GAP/PTMG AzESPU for 60 days samples showed viscoelastic behaviors with rubbery plateau and the flow region like GAP/PTMG PDESPU, but GAP/PTMG BDESPU did not show the flow region. From phase behaviors with ATR FT-IR, DSC and DMA analysis, GAP/PTMG AzESPU showed good phase-mixing between components. However, it represented viscoelastic behavior of TPE similar to GAP/PTMG PDESPM according to phase equilibrium progress with aging time.

감광성 폴리머 저항 페이스트를 이용한 Low Tolerance 후막 저항체

photosensitive; thick film resistor; tolerance; roller coating; uniform thickness

In this research, we intended to improve the tolerance of thick film resistor using photosensitive polymer resistor paste which was fabricated with alkali-solution developable photosensitive resin and conductive carbon black. At first, we investigated the effect of the selection of carbon black and photosensitive resin on the resistance range and tolerance level of polymer thick film resistor (PTFR). And then, a difference in resistance tolerance was evaluated according to the coating methods of photosensitive resistor paste on test board. In case that the photosensitive resistor paste was coated on whole surface of test board using screen printing, large positional tolerance was obtained because the formation of the thick film with uniform thickness was difficult. On the other hand, when the paste was coated with roller, the resistive thick film with uniform thickness was formed on the whole board area and the result of resistance evaluation showed low tolerance in ± 10% range. The tolerance of PTFR could be improved by combination of the precise patterning using photo-process and the coating process for the resistive thick film with uniform thickness.

초임계 메탄올을 이용한 유채유 바이오디젤 제조에 대한 반응인자들의 영향

biodiesel; rapeseed oil; supercritical methanol; transesterification

In this study, non-catalytic transesterification from rapeseed oil using supercritical methanol was carried out by varying the operation parameters such as temperature (320∼365 ℃), time (0∼20 min), pressure (10∼35 MPa), molar ratio of oil to methanol (1 : 15∼60) and agitation speed (0∼500 rpm). In order to evaluate the effects of reaction parameters on the content of fatty acid methyl esters (FAMEs), we carried out the study using a batch reactor. The content of FAMEs increased when the temperature increased. However, the content of FAMEs decreased with temperature above 350 ℃ and time above 5 min. The content of FAMEs increased with increasing the molar ratio of methanol to oil but the content of FAMEs was slightly affected by molar ratio of oil to methanol above 1 : 45 and pressure above 20 MPa. It was found that the agitation speed above 100 rpm slightly affected the content of FAMEs. The highest content of FAMEs in biodiesel (95%) was obtained under the reaction conditions: temperature of 335 ℃, time of 10 min, pressure of 20 MPa, molar ratio of 1 : 45 (oil to methanol) and agitation speed of 250 rpm.

Preparation and characterization of shape memory polymer networks based on carboxylated telechelic poly(ε-caprolactone)/epoxidized natural rubber blends

End-carboxylated polycaprolactone; Epoxidized natural rubber; Self-vulcanizable blends; Shape memory behavior; Thermomechanical properties

Shape memory polymer networks were prepared from blends of end-carboxylated telechelic poly(ε-caprolactone) (XPCL) and epoxidized natural rubber (ENR). The XPCL/ENR blends can form cross linked structure via interchain reaction between the reactive groups of each polymer during molding at high temperature. Degree of crosslinking of the blend network and their thermomechanical properties were characterized by gel content measurement, DSC and DMA. We found that the degree of crosslinking and crystalline melting transition temperatures was dependent upon the blend compositions as well as the molecular weight of the XPCL segment in the blends. The blends showed a good shapememory behavior such as good shape fixity as well as a high final recovery rate when they exhibit crystalline melting transition with a sufficiently high degree of crosslinking. And the response temperature of the recovery was well matched with T(m) of the samples.

HNBR compound와 RFL 처리된 Polyester 섬유의 접착 연구

HNBR; Polyester Fabric; RFL; Isocyanate

Adhesive strength was evaluated for the polyester fabric treated with various concentration of polymeric isocyanate to introduce functional group on the surface. Also experiments were performed to find out the type of latex, F/R mole ratio, and FR resin/latex weight ratio for the RFL solution to optimize adhesion between HNBR compound and the treated polyester fabric. Optimum adhesion strength was obtained when 7 wt% of the concentration of polymeric isocyanate, NBR latex because of the compatibility of HNBR compound, 1/1 of F/R mole ratio, and 20 wt% of FR resin/latex were applied. Optimum cure temperature for the RFL solution was 200 ℃ according to the results of peel test and the reason was determined by analyzing the ATR FTIR spectra of the RF resin according to the curing temperature.

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure

Silica Aerogels; Sodium Silicate; Ambient Pressure; Monolithic

The experimental results of aging time and temperature on the textural properties of water-glass (sodium silicate)-based silica aerogels are reported and discussed. Aging of the hydrogel for different times and temperatures led to an ability to increase the stiffness and strength of the networks. These improvements enabled the gel to withstand ambient pressure drying (APD) and, consequently, preserve the highly porous silica network without collapse. The pore size and volume increased with increasing aging temperature and time, while the specific surface area decreased. Monolithic aerogels with extremely low bulk density (~0.069 g/cm3), high specific surface area (820 m2g-1), large cumulative pore volume (3.8 cm3g-1), and high porosity (~96%) were obtained by aging at 60 ℃ for 18 hours. Therefore, easy synthesis of monolithic silica aerogels at ambient pressure is achievable using a relatively inexpensive silica precursor (sodium silicate).

Kinetics of the thermal degradation of wax materials obtained from pyrolysis of mixed waste plastics

Kinetic Analysis; Thermal Degradation; Wax Materials; Mixed Waste Plastics

We did a kinetic analysis of the thermal degradation of wax materials obtained from pyrolysis of mixed waste plastics using the nonisothermal weight loss technique with heating rates of 10, 20, 30 and 40 ℃/min. The weight loss data according to degradation temperature were analyzed by using the integral method based on Arrhenius form to obtain the kinetic parameters. To verify the effectiveness of the proposed kinetic analysis method, the experimental values were compared with those of the numerical integration results using kinetic parameters obtained in this work. It was found that the proposed kinetic analysis method gave reliable kinetic parameters of the thermal degradation of wax materials obtained from pyrolysis of mixed waste plastics.

폴리카보네이트/폴리(부틸렌 테레프탈레이트) 블렌드의 내화학성

PC/PBT blend; chemical resistance; mechanical property

Mechanical characteristics and chemical resistance have been investigated for PC/PBT blends. The changes in mechanical performance of PC/PBT blends was monitored during the treatment with both the PC thinner and general-purpose thinner to figure out the chemical resistance. The PC thinner greatly affected the mechanical properties of PC/PBT blends compared with general-purpose thinner. In the case of PC thinner treatment, the mechanical performance was improved with increased PC content at lower PC content ranges, say below 50%. However the mechanical performance was dropped rapidly at higher PC content ranges due to poor chemical resistance of PC. Transparent pure PC specimen became opaque after chemical treatment with PC thinner, and this can be interpreted by solvent-induced crystallization.

벤치 규모 연속반응시스템에서 저급 열분해유 분해반응에 대한 반응온도 프로그램의 영향

Mixed plastic waste; Low-quality pyrolytic oil; Thermal degradation; Reaction temperature program

The characteristics of product materials obtained from thermal degradation of low-quality pyrolytic oil were investigated in this study. The reactants were produced by pyrolysis of mixed plastic waste with film type in a commercial rotary kiln reaction system. The properties of reactants were measured by elemental analysis, calorimetry analysis and SIMDIST analyst. The result of degradation experiments with different reaction temperature programs was discussed through product yields, cumulative yields and production rates of oil products. The multi-step reaction temperature program resulted in higher yields of product oils and lower yields of residues than one-step reaction temperature program. The product characteristics such as production yield and the rate of oil products etc. were influenced by reaction temperature program in the continuous thermal degradation.

Optimization of parameters for the synthesis of bimodal Ag nanoparticles by Taguchi method

Bimodal; Ag nanoparticles; Taguchi method; Precipitation

Bimodal Ag nanoparticles were synthesized by modified precipitation process. Taguchi analysis was used in this study and the reaction time and temperature were the most influencing parameter on the particle size and the size distribution, respectively. The optimal conditions were determined by using Taguchi method and nano-sized Ag particles with bimodal shape were obtained.

Dehydrochlorination characteristics of waste PVC wires by thermal decomposition

Dehydrochlorination; Thermal decomposition; Waste PVC wires; Kinetic analysis

In this work, the dehydrochlorination characteristics of waste PVC wires in ASR have been studied by static quartz tube reactor under various reaction temperatures. The effect of CaO additive has been investigated to eliminate HCl obtained from thermal decomposition of waste PVC wires. Also to obtain the overall activation energy of dehydrochlorination reaction of waste PVC wires, the dynamic thermogravimetric analysis (TGA) curve and its derivative were analyzed. From this work, it was found that Friedman method gave the activation energies of 89.1-166.8 kJ/mol, while Ozawa method gave the activation energies of 94.2-118.6 kJ/mol and the activation energy increased as increasing of conversion. The formation of gaseous products significantly was suppressed and the amount of HCl was obviously reduced by addition of CaO.

Degradation of methylene blue in aqueous solution by ozone-based processes

Methylene blue; Ozonation; Catalytic ozonation (activated carbon TiO2/activated carbon); Catalyst characterization

The aim of this study was to compare the efficiency of conventional ozonation and catalytic ozonation (ozone/activated carbon (O3/AC) and ozone/TiO2/activated carbon (O3/TiO2/AC)) in the degradation of methylene blue (MB) component from MB aqueous solution. The removal rates of color and chemical oxygen demand (CODCr) were assessed to screen the most appropriate oxidative process of MB treatment. In this experiment conditions, the color was completely disappeared in the presence of TiO2/AC catalyst, after 40 min of reaction time. However, only ozone system still existed 11.8%MB in aqueous solution, while in case of O3/AC system MB of 4.6% was not removed. In the COD removal experiment, the catalytic ozonation process showed a superior performance, compared to that of the conventional ozonation. COD removal efficiency was significantly promoted in the presence of catalysts such as AC and TiO2. O3/TiO2/AC was found to be the most effective approach to eliminating the color and enhancing COD removal efficiency. The catalyst of TiO2/AC was characterized by using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).

감광성 폴리머 저항 페이스트 제조와 미세패턴 후막저항의 형성

photosensitive paste; thick film resistor; ultraviolet; carbon black; photo solder resist

Using an alkali-solution developable photosensitive resin and a carbon black as a conductive filler, photo-patternable pastes for polymer thick film resistor were fabricated and evaluated. A photo solder resist (PSR), which is usually used as protecting layer of printed circuit board (PCB), was used as a photosensitive resin so that ultraviolet exposure and alkali-aqueous solution development of paste were possible. After fabricating the photosensitive polymer resistor paste, the electrical properties of thick film resistors were measured using PCB test boards. Sheet resistance was decreased with increasing amount of carbon black, but the developability was limited in excess loading of carbon black. The sheet resistance was also reduced by re-curing and the change rate was smaller in higher carbon black loading. Moreover, finely patterned meander-type thick film resistors were fabricated using photo-process and large resistance up to several tens of sheet resistance could be obtained in small area by this technique.

단일 및 혼합 용매계 실리카 분산체의 점도 특성 및 유변학적 거동

silica; silica dispersion; rheology; hydrogen bonding; solvation effect

Dispersions of fumed silica are made in 6 kinds of mono-solvents and mixed solvents which have hydroxyl group, non hydroxyl group, different polarity, and different molecular size. The viscosity and rheology behaviors of the each dispersion are investigated according to the viewpoint of solvent characteristic. The silica dispersion in polar solvent with hydroxyl group is stable and low viscous sol. The silica dispersion in non-polar solvent with non-hydroxyl group is high viscous gel. When the solvent with hydroxyl group is added to the silica dispersions with non-polar solvents, they show the reduction of viscosity with solvent content. They have minimum critical content which shows no viscosity change. The minimum critical solvent content is decreased according to the polarity of solvents with no hydroxyl group. The solvation layer which is formed on the silica surface through hydrogen bonding between hydroxyl-containing solvent and the silanol group of silica surface is the reason of stable and low viscous sol. In case of non-polar solvent, silanol on adjacent silica particles interacted directly by hydrogen bonding show high viscous and flocculated gel.

퀴놀린-페놀 혼합용액의 습식산화

wet oxidation; quinoline; phenol; total organic carbon; induction period

Wet oxidations (WO) of quinoline in aqueous solution were carried out at 225 ℃ and 250 ℃. In the WO at 250 ℃, quinoline was degraded completely within 30 min and the reduction in total organic carbon (TOC) of 63% was achieved during 120 min. However, the rate of the reduction in TOC was only 13% within 240 min during the WO at 225 ℃. Nicotinic and acetic acid were found to be main intermediates formed during the oxidation of quinoline. With the addition of the homogeneous catalyst CuSO4 or more easily oxidizable phenol, WOs of quinoline were also carried out under moderate conditions at 200 ℃. The catalytic WO with CuSO4 of 0.20 g/L showed the destruction rates of quinoline and TOC comparable to those in the WO at 250 ℃. The WOs of quinoline-phenol mixture exhibited induction periods to degrade quinoline and phenol during which free radicals were produced to initiate WOs. With increasing initial concentrations of phenol at a given initial concentration of quinoline, the induction periods in the destructions of quinoline and phenol became shorter and the reduction in TOC increased from 60% to 75% during 180 min of the WOs. The reduction rate of an induction period decreased as increasing the initial concentration ratio of phenol to quinoline. On the other hand, phenol degradation in the WOs of quinoline-phenol mixtures required a longer induction period and proceeded slower compared to the case of the WO of phenol.

녹색과 청색 형광체 나노 분말의 합성 및 특성 평가

phosphor; characterization; nano powder; photoluminescence

Nano-sized green and blue phosphor powders were synthesized by liquid phase method to confirm the size and morphology. By using that process, the particle sizes of green and blue phosphor particles were 80 nm and 60 nm, respectively. The characteristic comparison of Zn2SiO4 : Mn and BAM : Eu was carried out and as a result, Zn2SiO4 : Mn powders showed an higher PL performance compared to BAM : Eu.

아지드화 폴리에피클로로히드린 고무/스티렌-아크릴로니트릴 공중합체 블렌드로부터 에너지함유열가소성탄성체 제조

energetic TPE; azidated PECH; SAN; blend

Polyepichlorohydrin rubber was treated with sodium azide (NaN3) to replace its chlorine by azide (N3). Then, the azidated polyepichlorohydrin rubber (Az-PECH) was blended with thermoplastic styrene-acrylonitrile copolymer with the rubber/plastic ratio of 80/20, 70/30 and 60/40 (wt/wt). The miscibility, mechanical and dynamic mechanical properties as well as elastic recovery properties of the blends were evaluated by DMA (Dynamic Mechanical Analyzer) and tensile tests. When azidation level in azidated PECH was upto 50%, the blends exhibited excellent miscibility, manifested by a single Tg, and fairly good elastic recovery. When azidation level was 75%, the blends showed phase separation. The miscible Az-PECH/SAN blends exhibited typical thermoplastic elastomer like properties, ie. melt processibility and high extensibility as well as good elastic recovery rate. It was also observed from combustion test that higher energy is released with the increase in the azidation level of the Az-PECH in the blends.

방향족/지방족 혼합 Diisocyanate를 포함하는 Polyurethane 분산체의 제조와 성질

polyurethane; anionic polyurethane dispersion; aromatic isocyanate; mixed isocyanate; thermal degradation temperature

An anionic polyurethane dispersions (PUDs) were synthesized from the poly (tetramethylene glycol) (PTMG, Mw = 2000g/mol), mixed isocyanate of dicyclohexylmethane-4,4'-diisocyanate (H12-MDI) and 4,4'-diphenylmethane diisocyanate (MDI), and dimethylol propionic acid (DMPA) as anionic site, following a prepolymer mixing process. Triethylamine (TEA) was used as a neutralization agent and the ethylenediamine (EDA) as the chain extender of the prepolymer. The effects of the DMPA molar ratio and aromatic diisocyanate content in the mixed isocyanate on the particle size and viscosity of PUD were studied. Also, the mechanical and thermal properties of the PUD cast films were discussed according to the molar ratio of DMPA and aromatic isocyanate content. It was found that the particle size and the viscosity of an anionic PUD decreased with increasing DMPA molar ratio but increased with increasing aromatic isocyanate (MDI) content in the mixed isocyanate at the constant DMPA content. Tensile strength of the PUD cast films increased and elongation at break decreased with increasing DMPA content at the constant mixed isocyanate molar ratios. In thermal degradation temperature of PUD cast films, the effect of DMPA contents was great but the effect of aromatic isocyanate contents at the low DMPA content was very slight respectively.

카본나노튜브에 담지된 몰리브데늄 카바이드 촉매의 제조 및 전기화학적 산화반응 특성

molybdenum carbide; carbon nanotube; catalyst preparation; electrochemical oxidation; acid treatment

Carbon nanotube supported molybdenum carbide catalysts were prepared as a function of various preparation conditions and characterized, and their catalytic activities were compared through electrochemical oxidation of methanol. To overcome the low activity of a transition metal catalyst, carbon nanotube was used as a support, and the amount and the kind of precursors, acid treatment method, and carburization temperature were varied for the catalyst preparation. ICP-AES, XRD and TEM were used for the catalyst characterization. Based on the various preparation methods of carbon nanotube supported molybdenum carbide catalysts (Mo2C/CNT), the size and the amount of supported catalysts could be controlled, and their effects on the electrochemical oxidation could be explained.

초임계 메탄올을 이용한 팜유 바이오디젤 제조에 관한 반응인자들의 영향

Biodiesel; Palm Oil; Supercritical Methanol; Transesterification

In this study, non-catalytic transesterification using supercritical methanol was performed for preparation of biodiesel from palm oil. In order to investigate the effects of reaction parameters such as molar ratio of methanol to oil(30:1~60:1), pressure(8~25 MPa), temperature(320~350 ℃), agitation speed(0~1,000 rpm) and time(0~20 min) on the content of fatty acid methyl esters(FAMEs), we carried out the study using a batch reactor. With increasing molar ratio of methanol to oil, the content of FAMEs increased. However, the content of FAMEs was little affected by molar ratio above 45 and pressure above 20 MPa. The content of FAMEs increased when the temperature increased. However, the content of FAMEs decreased with temperature above at 350 ℃ and with time above 5 min. It was found that the agitation speed above 500 rpm scarcely affected the content of FAMEs. The highest content of FAMEs in biodiesel(95%) was obtained under the reaction conditions: temperature of 335 ℃, pressure of 20 MPa, molar ratio of 45:1(methanol to palm oil), agitation speed of 500 rpm and time of 10 min.

NR/BR Compounds의 가황촉진제 병용에 의한 가황 특성 및 기계적 물성 연구

Natural Rubber; Butadiene Rubber; Accelerator; Cure Characteristics; Mechanical Properties

In the 1840s, Goodyear found out sulfur cure system, but cure time was too slow. So producing of rubber product takes a long time. In 1904, Oenslager et al. found that aniline is accelerated sulfur cure system. Recently, many rubber industries needed high yield and good quality. So, many researchers have studied a rubber system with fast vulcanization time and good mechanical properties. In this study, cure characteristics and mechanical properties of NR/BR compounds by accelerator with MBTS(2,2' Dithiobisbenzothiazole), TMTM(Tetramethylthiuram Monosulfide), ZDMC (Zinc dimethyldithiocarbamate), CBS(N-Cyclohexyl benzothiazolyl-2-sulfenamide), DPG(Diphenylguanidine) were evaluated. The results of the study indicate that cure charateristics(t90: 235 sec, Tmax: 5.77 Nm) and mechanical properties (100, 300% modulus : 2,180, 5.656 Mpa and tear strength: 59.58 kgf/cm) of NR/BR compounds shows efficient acceleration with MBTS 1.5 phr, TMTM 0.5 phr, DPG 0.15phr. This is due to the synergistic activity of ternary accelerator system in rubber vulcanization.

균일촉매를 이용한 페놀의 습식산화

Wet Oxidation; Phenol; Homogeneous Catalyst; Chemical Oxygen Demand

The wet oxidation of phenol has been investigated at temperatures from 150 to 250 ℃ and oxygen partial pressures from 25.8 to 75.0 bar with initial pH of 1.0 to 12.0 and initial phenol concentration of 10 g/l. Chemical Oxygen Demand COD has bee measured to estimate the oxidation rate. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography. The destruction rate of phenol have shown the first-order kinetics with respect to phenol and the changes in COD during wet oxidation have been described well with the lumped model. The impact of various homogeneous catalysts, such as Cu2+, Fe2+, Zn2+, Co2+, and Ce3+ ions, on the destruction rate of phenol and COD has also been studied. The homogeneous catalyst of CuSO4 has been found to be the most effective for the destruction of phenol and COD during wet oxidations. The destruction rate of formic acid formed during wet oxidations of phenol have increased as increasing temperature and CuSO4 concentration. The final concentrations of acetic acid which has been formed during wet oxidations and difficult to oxidize have increased with reaction temperature and with decrease in the catalyst load.

SBR/Organoclay Nanocomposites for the Application on Tire Tread Compounds

styrene butadiene rubber; organically modified layered silicates; latex method; morphology; cure characteristics; tan δ; wear resistance; calcium stearate

N,N-dimethyldodecylamine (tertiary amine)-modified MMT (DDA-MMT) was prepared as an organically modified layered silicate (OLS), after which styrene-butadiene rubber (SBR) nanocomposites reinforced with the OLS were manufactured via the latex method. The layer distance of the OLS and the morphology of the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By increasing the amount of N,N-dimethyldodecylamine (DDA) up to 2.5 g, the maximum values of torque, tensile strength and wear resistance of the SBR nanocomposites were increased due to the increased dispersion of the silicate layers in the rubber matrix and the increased crosslinking of the SBR nanocomposites by DDA itself. When SBR nanocomposites were manufactured by using the ternary filler system (carbon black/silica/OLS) to improve their dynamic properties as a tire tread compound, the tan δ (at 0 ℃ and 60 ℃) property of the compounds was improved by using metal stearates instead of stearic acid. The mechanical properties and wear resistance were increased by direct substitution of calcium stearate for stearic acid because the filler-rubber interaction was increased by the strong ionic effect between the calcium cation and silicates with anionic surface. However, as the amount of calcium stearate was further increased above 0.5 phr, the mechanical properties and wear resistance were degraded due to the lubrication effect of the excessive amount of calcium stearate. Consequently, the SBR/organoclay nanocomposites that used carbon black, silica, and organoclay as their ternary filler system showed excellent dynamic properties, mechanical properties and wear resistance as a tire tread compound for passenger cars when 0.5 phr of calcium stearate was substituted for the conventionally used stearic acid.

상압 플라즈마 표면처리와 형태학적 조절에 의한 에폭시/폴리아미드/MPD 반응성 블렌드의 접착력 향상

epoxy; polyamide; AP plasma treatment; structural adhesive; morphology.

The morphology and mechanical properties of epoxy/polyamide/MPD reactive blends with various amount of polyamide were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of high soluble polyamide in epoxy ranged from 0 to 30 phr, and the cure reaction occurred at 170℃ for 30 min. The start and maximum exothermic temperature in heat flows during cure reactions appeared at almost same temperature, indicating that soluble polyamide could rarely hinder the cure reactions. From the SEM images, it was found that the size of separated-phase was very fine about 100-300 nm, and at 20 phr of polyamide the boundary of separated-phase was unclear and the phase revealed co-continuous. By AP plasma treatment of specimen surface, the adhesion strength was increased by 20% due to enhanced surface free energy. By blending 20 phr of polyamide with epoxy, the adhesion strength was increased by 50% due to co-continuous phase in morphology. By considering the surface treatment of specimen and morphological tuning of the blends, it can be expected that the improvement in toughness and excellent adhesion strength can be achieved in structural adhesive systems.

이미다졸(2E4MZ-CN) 촉매 첨가에 의한 에폭시/폴리아미드/MPD 반응성 블렌드의 경화 반응, 형태학적 특징 및 접착력 향상 연구

epoxy; polyamide; AP plasma treatment; structural adhesive; morphology.

The morphology and mechanical properties of epoxy/polyamide/MPD/2E4MZ-CN reactive blends with various amount of catalyst were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of catalyst ranged from 0 to 3 phr, and the cure reaction occurred at 170℃ for 30 min. The maximum peaks in heat flow during cure reactions appeared at slightly lower temperature with increasing catalyst content, indicating that the cure reactions start at lower temperature by adding catalyst and polyamide rarely hinders the cure reaction paths. The co-continuous morphology was found in epoxy/polyamide(20 phr) blends and by adding catalyst to the blends much clearer and uniform co-continuous phase was observed. The surface tension of the mechanical test specimen was increased due to the AP plasma surface treatment, and then adhesion strength was increased by over 20% by adding 2 phr of catalyst to the blends. When considering morphological tuning of the blends by means of catalyst incorporation, it is expected that the increased elongation and adhesion strength can be achieved in the structural adhesive systems.

폴리페닐렌에테르계 고분자 기판 소재의 유전특성에 대한 가교제 및 난연제의 영향

poly(phenylene ether); dielectric loss; dielectric constant; crosslinking; gel content.

Polymer substrates were fabricated by using poly(phenylene ether) as a base resin, N,N'- m-phenylenedimaleimide(PDMI) as a crosslinking agent and decabromodiphenylethane as a flame retardant. The effects of crosslinking agent and flame retardant on physical properties such as dielectric property of the substrate were investigated. Thermal curing feature of PDMI with or without an initiator was analyzed by DSC, and then, PPE-PDMI test compositions were designed based on this result. Composite sheets were cast by film coater, laminated under vacuum and pressure, and then, the changes of dielectric constant, dielectric loss, peel strength, solder heat resistance and inflammability according to increasing amount of PDMI and flame retardant were evaluated. Dielectric constant and dielectric loss showed increasing trend with increasing amount of PDMI and flame retardant, but solder heat resistance and inflammability were improved. Peel strength was obtained higher than 1 kN/m when PDMI above 10 wt% was added, but slightly decreased as the amount of flame retardant increased. From the measured gel contents, the reaction mechanism of PPE-PDMI system was deduced to the formation of network structure by crosslinking PDMI with PPE rather than the formation of semi-IPN structure. In conclusion, the polymer composite substrate materials with dielectric constant of 2.52∼2.65 and dielectric loss below 0.002 at 1 GHz were obtained and they will be proper for high frequency applications.

Modeling and simulation of evaporation-pyrolysis processes of a naturally smoldering cylindrical cellulosic materials rod: Effect of smoldering rate on product concentrations

biomass; cellulosic materials; pyrolysis; modeling; smoldering

This study developed the mathematical model of the simultaneous transport and chemical processes inside naturally smoldering cellulosic materials. Matlab is employed for solving heat and mass transfer model as well as chemical kinetic model equations represented by a Distributed Activation Energy Model (DAEM). Simulations are carried out for the smoldering rate ranging from 0.18 cm/min to 0.4 cm/min and a final fixed pyrolysis temperature of 450℃. On the basis of the model, the product yields, the evolution rate, and the influences of smoldering rate on the 22 selected volatile species out of 45 pyrolysis precursors are predicted. (c) 2007 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

실리카 입자를 이용한 눈부심 방지용 박막의 제조 및 특성

hollow silica; anti-glare; transmittance; haze; gloss

The effect of filler type and dispersion time on thin film characterization is studied. Hollow silica powders which have the advantage of transmittance are selected. In this paper, the characterization of haze, transmittance, and gloss are analyzed in terms of filler concentration and coating thickness, respectively. As a result, the value of haze and gloss increased with increasing of filler concentration and coating thickness, respectively. In addition, the variation of transmittance by filler concentration and coating thickness is not occurred. In conclusion, it is assumed that hollow silica powders as a filler have an advantage of concentration increment and transmittance.

Ru/C 촉매를 이용한 p-Toluidine의 선택적 수소화 반응에 있어서 공정변수의 최적화연구

p-Toluidine; Ru/C catalyst; hydrogenation; process variables; alkali additive

Hydrogenation reactions of p-toluidine over Ru/C were performed while varying reaction temperature, the hydrogen pressure, catalyst loading, solvent, and alkali additive and the effects on the reaction rates and product distribution were examined. 4-Methylcyclohexylamine was generated as a main product and bis(4-methyl cyclohexyl)amine was obtained as a resentative side-product for the hydrogenation reaction of p-toluidine. The selectivity of MCHA decreased with reaction temperature and the hydrogen pressure while increased with catalyst loading. IPA was the best solvent for MCHA. A mechanism of hydrogenation reaction of p-toluidine was suggested from the results. It was found that the presence of alkali salt increased MCHA by reducing BMCHA and rates of hydrogen reaction increased.

폴리에틸렌에틸아크릴레이트/카본나노튜브 나노복합체의 제조 및 물성

poly(ethylene-co-ethyl acrylate); multi-walled carbon nanotube; nanocomposites; morphology

Multi-walled carbon nanotubes (MWCNT)-reinforced poly(ethylene-co-ethyl acrylate) (EEA) nanocomposites were prepared by both melt and solution mixing methods. The mechanical, thermal, and electrical properties were investigated as a function of type and loading of CNT. The tensile strength and modulus increased, while elongation at break decreased with increasing MWCNT content. The hollow-type MWCNT showed an improved tensile strength and elongation at break compared with a conventional MWCNT. The thermal degradation temperature was increased by around 40 ℃ with increasing the amount of MWCNT. The melt-mixed composites showed the highest volume resistivity. In the case of solution-mixed composites, the conventional MWCNT was estimated to show much lower volume resistivity than that of hollow MWCNT. The number and length of extruded CNT onto the fractured surface increased by both increasing the content of CNT and employing the tensile strain to the sample. The melt-mixed specimens showed much smaller number and shorter length of extruded CNT.

혼합폐플라스틱의 열분해로부터 생성된 고분자성분의 열적분해

thermal degradation; waste plastics; pyrolysis; high molecular components

The thermal degradation characteristics of high molecular components obtained from pyrolysis of mixed waste plastics have been studied by thermogravimetric analysis (TGA) and gas chromatography spectrometry (GC-MS). The kinetics of thermal degradation has been studied by a conventional nonisothermal thermogravimetric technique at several heating rates between 10 and 50 ℃/min. The dynamic thermogravimetric analysis curve and its derivative have been analyzed using a variety of analytical methods reported in the literature to obtain information on the kinetic parameters such as activation energies and reaction orders. The yields of liquid products have been monitored by batch pyrolysis reactor under various reaction temperatures and reaction times. And the characteristic of liquid products with the increase in reaction temperature has been performed by GC-MS.

적색 형광체 나노 분말의 합성 및 특성 평가

phosphor; characterization; nano powder; photoluminescence

Nano-sized phosphor powders were synthesized by the liquid phase method to confirm the size and morphology. By using the process, red phosphor particles with a size of 80 nm were obtained. The characteristic comparison of Y2O3:Eu3+ and YBO3:Eu3+ was carried out and, as a result, YBO3:Eu3+ powders using boric salt showed an aggregated morphology and lower PL performance compared to Y2O3:Eu3+.

Formation and Surface Modification of Fe3O4 Nanoparticles by Co-precipitation and Sol-gel Method

Fe3O4; sol-gel; co-precipitation; nanoparticle; surface modification

Fe3O4 nanoparticles were synthesized by co-precipitation of Fe3+ and Fe2+ with NH4OH, and then silica was coated onto the surface of Fe3O4 by hydrolysis of TEOS. Coupling agent was also coupled with the surface of the nanoparticles and protein was immobilized. Morphology, particle size, and magnetic properties of the nanoparticles were characterized by TEM, DLS, and VSM, respectively. As a result, silica coated Fe3O4 nanoparticles with an average size of 15 nm were obtained and super-paramagnetic properties were achieved.

Comparison of Pyrolysis Kinetics Between Rigid and Flexible Polyurethanes

pyrolysis; thermogravimetric analysis; flexible and rigid polyurethane; kinetics

The pyrolysis kinetics of rigid and flexible polyurethane were examined using thermogravimetric analysis. During the experiment, some of the main compounds were detected. Rigid polyurethane produced five types of low molecular weight organic products, and flexible polyurethane produced at least eleven types of low molecular weight organic products. The main decomposition range of rigid polyurethane took place between 200 and 410 ℃, and flexible polyurethane between 150 and 500 ℃. A consecutive kinetic model for the pyrolysis of polyurethanes is proposed. The model was able to simulate the experimental curves with good agreement. Using this kinetic model, the kinetic parameters such as activation energy, frequency factor and reaction order could be determined. The average activation energy of flexible polyurethane was 203.1 KJ/mol, which is almost 1.59 times higher than that of rigid polyurethane, 127.7 KJ/mol.

Polyurethane/silica Composites, Prepared Via in-situ Polymerization in the Presence of Chemically Modified Silicas

modified silica; polyurethane/silica composite; glycidoxypropyltrimethoxysilane; diethanolamine

A hydrophilic fumed nanosilica surface was modified with γ-glycidoxypropyltrimethoxysilane, and subsequently with diethanolamine. The chemically modified silicas were used for the in-situ preparation of polyurethane/ silica composites. The doubly modified silica gave rise to a greater enhancement of the tensile strength and elongation at break of the polymer composite films, as compared to the singly modified silica. The more improved tensile properties were attributed to the more increased number of covalent links between the modified silica surface and polyurethane chains, and the better dispersion of the silica particles in the polyurethane matrix.

Preparation and Characterization of Porous Boehmite Particles and Pt/γ-Alumina

boehmite; platinum; alumina; catalyst preparation

Hydrogenation reactions are utilized in various applications ranging from large-scale series catalyst processes in the oil refinery industry to small-scale batch processes in the pharmaceutical and fine chemical industries. Catalysts that consist of active materials often have inferior mechanical strength or thermal stability and are costly because they contain novel metals. Catalysts containing dispersed active materials in a suitable support are used to overcome these shortcomings. Porous Boehmite was fabricated, and the possibility of utilizing a metal catalyst used in hydrogenation reactions to impregnate the porous Boehmite was investigated. In addition, several properties, such as the metal particle size and the hydrogenation reaction rate, of the catalysts incorporating different supports were studied.

rac-Me2Si(2-p-tolylindenyl)2ZrCl2 촉매를 이용한 에틸렌/1-옥텐의 공중합 특성

rac-Me2Si(2-p-tolylindenyl)2ZrCl2 catalyst; metallocene catalyst; ethylene/1-octene copolymerization; comonomer effect; 2-p-tolyl substituent

The copolymerization characteristics of a newly-synthesized catalyst, rac-Me2Si(2-p-tolylindenyl)2ZrCl2, and its analogue, rac-Me2Si(Ind)2ZrCl2, were examined in the ethylene/1-octene copolymerization while varying the concentration of 1-octene in the reaction mixture. The activity of rac-Me2Si(2-p-tolylindenyl)2ZrCl2 catalyst was decreased with increase of comonomer concentration, which is different from the usual comonomer effect of the metallocene catalysts with a bridge structure. The contents of 1-octene in the copolymer from the catalyst with 2-p-tolyl substituent were higher than those from the catalyst without that substituent. The melting point, crystallinity, and molecular weight decreased with comonomer content which was more apparent for rac-Me2Si(2-p-tolylindenyl)2ZrCl2 catalyst.

Effective combination of non-thermal plasma and catalyst for removal of volatile organic compounds and NOx

Non-thermal Plasma; Catalyst; Volatile Organic Compounds; NOx

A plasma/catalyst hybrid reactor was designed to overcome the limits of plasma and catalyst technologies. A two-plasma/catalyst hybrid system was used to decompose VOCs (toluene) and NOx at temperature lower than 150 ℃. The single-stage type (Plasma-driven catalyst process) is the system in which catalysts are installed in a nonthermal plasma reactor. And the two-stage type (Plasma-enhanced process) is the system in which a plasma and a catalyst reactor are connected in series. The catalysts prepared in this experiment were Pt/TiO2 and Pt/Al2O3 of powder type and Pd/ZrO2, Pt/ZrO2 and Pt/Al2O3 which were catalysts of honeycomb type. When a plasma-driven catalyst reactor with Pt/Al2O3 decomposed only toluene, it removed just more 20% than the only plasma reactor but the selectivity of CO2 was remarkably elevated as compared with only the plasma reactor. In case of decomposing VOCs (toluene) and NOx using plasma-enhanced catalyst reactor with Pt/ZrO2 or Pt/Al2O3, the conversion of toluene to CO2 was nearly 100% and about 80% of NOx was removed.

Effect of A-Zeolite on the Crystallization Behavior of In-situ Polymerized Poly(ethylene terephthalate) (PET) Nanocomposites

PET; A-zeolite; nanocomposite; crystallization behavior; fine structure

The crystallization behavior and fine structure of poly(ethylene terephthalate) (PET)/A-zeolite nanocomposites were assessed via differential scanning calorimetry (DSC) and time-resolved small-angle X-ray scattering (TR-SAXS). The Avrami exponent increased from 3.5 to approximately 4.5 with increasing A-zeolite contents, thereby indicating a change in crystal growth formation. The rate constant, k, evidenced an increasing trend with increases in A-zeolite contents. The SAXS data revealed morphological changes occurring during isothermal crystallization. As the zeolite content increased, the long period and amorphous region size also increased. It has been suggested that, since PET molecules passed through the zeolite pores, some of them are rejected into the amorphous region, thereby resulting in increased amorphous region size and increased long period, respectively. In addition, as PET chains piercing into A-zeolite pores cannot precipitate perfect crystal folding, imperfect crystals begin to melt at an earlier temperature, as was revealed by the SAXS profiles obtained during heating. However, the spherulite size was reduced with increasing nanofiller content, because impingement between adjacent spherulites in the nanocomposite occurs earlier than that of homo PET, due to the increase in nucleating sites.

다이사이클로펜타다이에닐 비스페놀 시아네이트 에스터와 폴리페닐렌에테르를 이용한 저유전손실 고분자 기판 소재

dielectric loss; cyanate ester; polyphenylene ether; dissipation factor; peel strength

Polymer substrate materials with low dielectric loss were obtained by fabricating the composite using dicyclopentadienyl bisphenol cyanate ester oligomer and polyphenylene ether (PPE). From the analysis of the curing reaction of oligomer and catalyst, it was observed that the optimum amount of catalyst was 0.02 phr of Zn content. It was applied to the fabrication of polymer composite. By changing oligomer/PPE weight ratio, the peel strength and the gel content of the fabricated composites were measured, and then, the dielectric constant and the dissipation factor were measured in the GHz frequency range. The amount of PPE affected the peel strength and the dielectric properties of composites. However, the amount of catalyst did not affect them at all. Resulting from all experiments, we obtained polymer composite laminates having the peel strength of above 1 kN/m and the low dissipation factor of 0.004 at 1 GHz.

폴리카보네이트/폴리(부틸렌 테레프탈레이트) 블렌드의 유변학적 및 파괴특성

PC; PBT; trans-esterification; melt index; dynamic property; impact strength; tensile strength

Trans-esterification behavior of polycarbonate/poly(butylene terephthalate)(PC/PBT) blends was investigated during the melt mixing process. Rheological and fracture behaviors, and fracture morphology were also investigated as a function of PC/PBT blend ratio. Based on FT-IR and 1H-NMR results, a transesterification reaction was confirmed to occur between PC and PBT during the melt mixing process. The melt index(MI) decreased with increased PC content, indicating the higher flow resistance of PC. The storage and loss moduli were increased by increasing the PC loading, and the PC/PBT blends were rheologically incompatible based on the Cole-Cole plot. The tensile property increased linearly with the increased PC content. However, the impact strength increased until 50 wt% of PC loading, notably around 30∼40 wt%, and then was levelled off at 50 wt%. Rough ridges were formed on the impact fracture surfaces above the 40 wt% of PC content, supporting the observed higher impact strength in this range.

다중벽 카본나노튜브가 보강된 고분자 나노복합체의 기계적, 열적, 전기적 특성

carbon nanotubes; nanocomposites; solution mixing; crystallinity; dual filler system

Semiconducting layers are thin rubber film between electrical cable wire and insulating polymer layers having a volume resistivity of ∼102 Ωcm. Commercial semiconducting layers are composed of polymer composites reinforced with more than 30 wt% of carbon blacks. A new semiconducting material was suggested in this study based on the carbon nanotube(CNT)-reinforced polymer nanocomposites. CNT-reinforced polymer nanocomposites were prepared by solution mixing and precipitation with various polymer type and dual filler system. The mechanical, thermal and electrical properties were investigated as a function of polymer type and dual filler system based on CNT and carbon black. The volume resistivity of composites was strongly related with the crystallinity of polymer matrix. With the decreased crystallinity, the volume resistivity decreased linearly until a critical point, and it remained constant with further decreasing the crystallinity. Dual filler system also affected the volume resistivity. The CNT-reinforced nanocomposite showed the lowest volume resistivity. When a small amount of carbon black(CB) was replaced the CNT, the crystallinity increased considerably leading to a higher volume resistivity.

Recrystallization of L-PLA Fine Particles by Supercritical Anti-Solvent (SAS) Process

recrystallization; L-PLA; fine particles; supercritical anti-solvent

Poly-L-lactic acid (L-PLA) particles were produced through a continuous supercritical anti-solvent(SAS) process in an effort to evaluate the possibility of controlling the microparticle size and distribution. SAS experiments were performed by studying the influences of the pressure, temperature, concentration of liquid solution, flow rate of anti-solvent and liquid solution, and nozzle diameter. SEM images of the processed materials were used to analyze the morphology, mean particle size, and particle size distribution (PSD). Upon optimization, L-PLA microparticles were successfully precipitated by the SAS process, using carbon dioxide (CO2) as the supercritical anti-solvent and methylene chloride (CH2Cl2) as the liquid solvent.

제올라이트-효소 촉매를 이용한 ρ,α-Dimethyl Benzyl Alcohol의 2상 동적 속도론적 광학분할

biphasic dynamic kinetic resolution; ρ,α-dimethyl benzyl alcohol; acidic zeolite; immobilized enzyme; process variables

ρ,α-dimethyl benzyl alcohol was resolved by the biphasic dynamic kinetic resolution (DKR). Acidic zeolite was used as a racemization catalyst while immobilized enzyme was employed for kinetic resolution. The effects of the process variables including nature of acyl donor, reaction temperature, substrate concentration, ratio of the two catalysts and stirring rate on the conversion and enantiomeric purity of the product were investigated. In DKR of ρ,α-dimethyl benzyl alcohol, the product of 99% ee was obtained with a maximum yield of 88%. The high performance of the catalyst system was maintained in the condition of higher TON and under repeated use.

고분자로 표면 코팅된 BaTiO3와 이를 이용한 폴리이미드 나노복합필름의 제조 및 특성

polyimide; nanocomposite; dielectric constant; barium titanate; organophilic inorganic particle

We have prepared organophilic inorganic particles and polyimide (PI) nanocomposite having excellent thermal stability and high dielectric constant that can be used for electronic application such as capacitor. We have chosen barium titanate (BT), a high dielectric constantmaterial and its surface was coated with nylon 6 to improve the affinity with PI. The FT-IR and TEM studies showed that the organophilic inorganic particle (BTN) has a polymer shell with thickness of 5 nm. We have suggested that it is possible to control the thickness of coating surface and also indicated the relationship between the ratio of inside and outside radius of BTN and the weight fraction of BT. The PI nanocomposite films based on poly(amic acid) and BTN were prepared by cyclodehydration reaction. The homogeneous dispersion of BTN in PI matrix was identified by using SEM. We have investigated the effect of BTN content on the coefficient of thermal stability, integral procedural decomposition temperature (IPDT), and dielectric constant of PI nanocomposite films.

Dihydrocinchonidine으로 개질된 Rh-Pt/Al2O3 이원금속 촉매를 이용한 Ethyl Pyruvate의 비대칭 수소화

Rh-Pt/Al2O3; bimetallic catalyst; asymmetric hydrogenation; ethyl pyruvate; sequential impregnation

Rh-Pt/Al2O3 catalysts were used for the first time to study its reaction characteristics in the asymmetric hydrogenation of ethyl pyruvate. The catalysts were prepared either by impregnation of Rh on a commercial Pt/Al2O3 or by sequential impregnation of Rh followed by impregnation of Pt on Al2O3. Reaction rate and enantiomeric excess (ee%) were compared according to the preparation method, Rh contents, and the reduction temperature of the catalyst. The physical characteristics of the catalysts were analyzed using XRD and TEM. Bimetallic Rh-Pt/Al2O3 catalysts showed an improved reaction rate and optical purity (63.6 ee%) with increasing the reduction temperature. The variation of the Rh contents as well as the preparation method elicited a big difference on the reaction rate, while enantiomeric excess (ee%) was lower (56∼60%) with all bimetallic catalysts than with monometallic Pt/Al2O3 catalyst.

반회분식 반응을 이용한 단분산 ZnO 나노 입자의 제조 및 입자의 크기와 입도 분포에 영향을 미치는 HPC의 작용

ZnO; HPC; sol-gel; hexagonal

To synthesize ZnO colloidal solution by a sol-gel process, zinc acetate (C4H6O4Zn·2H2O·0.2 mol) and lithium hydroxide (LiOH·H2O·0.14 mol) in the ethanol were added to the solution containing a dispersing agent, hydroxypropyl cellulose (HPC). The nanosize and physical shape of the synthesized ZnO particles were determined by HPC acting as the dispersing agent. Nanosized ZnO particles were also obtained by a precipitation method based on zinc-2-ethylhexagonate. The precipitates were characterized by DLS, XRD, FE-SEM, and UV-vis. As the results, the ZnO colloids tend to self-assemble into a well-ordered hexagonal close-packed structure. The ZnO nanoparticles have an average diameter of nearly 40 nm with a narrow size distribution.

폐폴리우레탄의 열적 산화분해에 대한 속도론적 연구

kinetic analysis; thermal-oxidative degradation; waste polyurethane

The kinetics of the thermal-oxidative decomposition of waste polyurethane (PU) according to oxygen concentration has been studied using a non-isothermal thermogravimetric technique at several heating rates from 10 to 50 ℃/min. A kinetic model accounting for the effects of the oxygen concentration by the differential and integral method based on Arrhenius equation was proposed to describe the thermal-oxidative decomposition of waste PU. To obtain the information on the kinetic parameters such as activation energy, reaction order, and pre-exponential factor, the thermogravimetric analysis curves and its derivatives have been analyzed using the kinetic analysis method proposed in this work. From this work, it was found that reaction orders for oxygen concentration had a negative sign, and activation energy decreased as the oxygen concentration increased. It was also found that the kinetic parameters obtained from the integral method using the single heating rate experiments varied with heating rates. Therefore, it is thought that the differential method using the multiple heating rate experiments more effectively represents the thermal-oxidative decomposition of waste polyurethane.

다양한 구조의 방향족 아민으로 개질된 친유기성 MMT의 제조와 이를 이용한 폴리이미드 나노복합필름의 특성

layered silicate; organophilic MMT; polyimide (PI); nanocomposite

In this work, we have prepared organophilic MMT having thermal stability by ion exchange reaction of various aromatic ammonium salts with MMT containing sodium ion. The organic modifiers having alkyl side chains and amine functional group were successfully synthesized by effectively introducing the surfaces of MMT via ion exchange reaction to form organophilic MMTs with a view to improve the reactivity and thermal stability. The WAXD patterns of organophilic MMT showed the more increased gallery spacing by 3.3 Å than that of the pristine MMT and also the onset of initial decomposition of organophilic MMT was 275℃ as determined by a thermogravimetric analysis. The polyimide (PI) nanocomposite films based on poly(amic acid) and organophilic MMT were prepared by a solution blending followed by cyclodehydration reaction. We have investigated the dispersity of organophilic MMTs in PI matrix by using WAXD and the effect of the organophilic MMT content on the mechanical properties of PI nanocomposite films was studied.

효소촉매 담지체용 다공성 베마이트 제조

AlO(OH); porous material; biocatalyst support; inorganic support

Synthesis of Boehmite particles were performed through the precipitation of aluminium nitrate (Al3(NO3)3 9H2O) with ammonia water (NH4OH) by changing solution pH, mixing procedure, temperature, and feeding flux. The influence of the synthesis condition, which affected on the pH range of the Boehmite formation, particle morphology and pore property, was investigated. The Boehmite particles were formed in the reaction solution of pH 7.5 9. The particles prepared by P2jet type which maintained the pH uniformly during the precipitation resulted in homogeneous particles and pores because of the constant concentration of the reacted ion in the solution. It was resulted in the improvement of the specific surface area and pore volume of the particle at the same time. With the increasing of temperature and the decreasing of the feeding flux, it was occurred the large specific surface area and pore volume. Also it was presented the fibrillar shaped particles upper 60℃ of the reaction temperature. In this study, the optimal condition of the porous Boehmite was in P2jet type with 90℃ of reaction temperature and 2.5 mL/min of the feeding flux. At this time, the specific surface area, pore volume, and average pore size was 385.46 m2/g, 1.0252 mL/g, 10 nm, respectively.

공기분위기에서 ZnO를 첨가한 PVC와 PS 혼합물의 분해특성에 관한 연구

decomposition; poly(vinyl chloride); polystyrene; ZnO; air atmosphere

The effect of ZnO in the decomposition of poly(vinyl chloride) (PVC) and polystyrene (PS) mixtures in air atmosphere has been studied by thermogravimetry (TG) and gas chromatograph-mass spectrometry (GC-MS) under various mixing ratios and reaction temperatures. From this work, it can be seen that the yields of a liquid product were increased with the increase of PS in mixtures, whereas those of gaseous products were decreased. And the yields of a gaseous product and HCl were decreased with the increase of ZnO in mixtures. It was also found that HCl was rarely produced at ZnO/Mixture = 0.5 by the effect of ZnO in dehydrochlorination of PVC.

플라즈마 처리된 폴리스티렌 막을 통한 순수한 CO2와 N2 기체의 선택·투과 특성

Polystyrene; Plasma Treatment; Permeation; Selectivity

The surface of polystyrene membrane treated by Ar, O2 plasma, and the effects were observed before and after the treatment and permeability of CO2, N2 and selectivity of CO2 relative to N2 was measured using continuous flow gas permeation analyzer (GPA). The mole ratio of O over C in the surface was increased from 0 to 0.179 with Ar plasma treatment and route mean square of surface was increased from 15.86 Å to 71.64 Å. Therefore the contact angle was decreased from 89.16° to 18.1°. Thus Plasma treatments made surface of membrane tend to be highly hydrophilic. The optimum condition for the CO2 permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of Ar (60 W, 2 min, 70 °C) plasma treatment was 1.14×10^-12[m3(STP)·m/m2·sec·atm] and 4.22. In the case of O2 plasma treatment, the contact angle was decreased at 13.56° with increase of O/C ratio (0.189 Å) and route mean square of surface (57.10 Å). The optimum condition for the CO2 permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of O2 (90W, 2 min, 70°C) plasma treatment was 7.1×10^-12[m3(STP) · m/m2·sec · atm] and 11.5. After plasma treatment, the changes of membrane surface were all subtly linked with both cross-linking and etching effects. Finally, it was confirmed that the gas permeation capacity and selectivity of the modified membrane with plasma could be improved by an appropriate control of the plasma conditions such as treatment time, the power input and sort of plasma gas.

A kinetic analysis of the thermal-oxidative decomposition of expandable polystyrene

Kinetic Analysis; Thermal-Oxidative Decomposition; Expandable Polystyrene

The kinetics of the thermal-oxidative decomposition of expandable polystyrene (EPS) was studied by a conventional thermogravimetric technique in various concentrations of oxygen from 0 to 21%. A kinetic model that accounts for the effects of oxygen concentration was proposed to describe the thermal-oxidative decomposition of EPS. The thermogravimetric analysis curve and its derivative have been analyzed by using differential and integral methods with modification of the Friedman and Coats-Redfern methods. The activation energy, the pre-exponential factor, and the reaction order for unreacted material and oxygen concentration have been determined. When oxygen was present, the activation energy was reduced significantly.

Crystallization of acetaminophen micro-particle using supercritical carbon dioxide

Acetaminophen; Supercritical Fluid; Anti-solvent; Particle

Fine particles of acetaminophen were produced by Aerosol Solvent Extraction System (ASES). The experiments were conducted to investigate the effects of various temperatures, pressures, solvents, solution concentrations and solution feed volume rates on particle size and morphology. The choice of solvent appears to be very important for getting specific particle shape and size. The result shows that when ethyl acetate is used as a solvent, the irregular and acicular morphology of raw material is recrystallized to be regular and monoclinic. The average particle size of recrystallized acetaminophen from ethyl acetate solution has been measured to be 3-4 μm, which was about 1/20th of raw acetaminophen in size. The particle size distribution range also became narrow from 82 μm to 4.9 μm.

A comparative study of liquid product on non-catalytic and catalytic degradationof waste plastics using spent FCC catalyst

Non-catalytic Degradation; Catalytic Degradation; Spent FCC Catalyst; Waste Plastic Type; Characteristicsof Liquid Product

Non-catalytic and catalytic degradation of waste plastics (high-density polyethylene (HDPE), low-densitypolyethylene (LDPE), polypropylene (PP) and polystyrene (PS)) using spent fluid catalytic cracking (FCC) catalystinto liquid product were comparatively studied with a stirred semi-batch reactor at 400oC, under nitrogen stream. Liquidproduct characteristics were described by cumulative distribution as a function of lapse time of reaction, paraffin, olefin,naphthene and aromatic (PONA) composition, and also carbon number distribution on plastic type of reactant. Fordegradation of waste PE with relatively high degradation temperature, the effect of adding spent FCC catalyst greatlyappeared on cumulative distribution of liquid product with a reaction lapse time, whereas those for waste PP and PSwith low degradation temperature showed a similar trend in both non-catalytic and catalytic degradation at 400oC. InPONA and carbon number distribution of liquid product, the characteristics of waste PS that was mainly degraded byend chain scission mechanism were not much altered in presence of spent FCC catalyst. However, waste polyolefinicpolymer that was degraded by a random chain scission mechanism significantly differed on PONA and carbon num-ber distribution of liquid product with or without spent FCC catalyst. The addition of spent FCC catalyst in degradationof polyolefinic polymer, which economically has a benefit in utilization of waste catalyst, significantly improved thelight olefin product by its high cracking ability and also the aromatic product by cyclization of olefin as shape selectivityin micropore of catalyst.

Thermal degradation of nitrogen-containing polymers, acrylonitrile-butadiene-styreneand styrene-acrylonitrile

Thermal Degradation; N-containing Recycled Plastics (ABS & SAN); Degradation Temperature; Characteris-tics of Liquid Product

Thermal degradation of nitrogen (N)-containing recycled plastics (styrene-acrylonitrile (SAN), acrylonitrile-butadiene-styrene (ABS)) was carried out in a stirred-batch reactor at 300-400oC under nitrogen stream. The degrada-tion oil began to be generated over 300oC. Recycled SAN plastic was converted to oil with 91.3wt% yield at 380oC,while only 70.9wt% of recycled ABS plastics was converted to oil at the same temperature and both oils containedabout the same 3.7wt% nitrogen as an elemental basis. Rate of oil formation from the thermal degradation of SANwas much higher than that of ABS, but showed a similar degradation pattern in terms of chemical composition. In oilproducts, aromatic contents obtained at 360oC were 70wt% for SAN and 79wt% for ABS, respectively, and decreasedto 59wt% and 57wt% at 380oC with increasing degradation temperature. Dominant product of both degradation oilswas styrene, and the following was ethylbenzene for ABS, but none in case of SAN. Both oils contained the N-contain-ing plastic additives that give rise to a confusion for the identification of authentic N-containing degradation products.

Structure and Properties of the Organoclay Filled NR/BR Nanocomposites

organoclay; NR/BR nanocomposites; coupling agent

Organoclay, was applied as a filler, in place of carbon black and silica, to a natural rubber (NR)/butadienerubber (BR) blend. A compounding method was used to disperse and separate the layered silicates. The effect of acoupling agent on the vulcanizates was evaluated using both the silica and organoclay filled compounds. After thecompounding processes were completed, the XRD diffraction peaks disappeared, but then reappeared after vulcani-zation. The scorch times for the organoclay-filled compounds were very short compared to those for carbon blackand silica-filled compounds. The organoclay-filled compounds showed high values of tensile strength, modulus, tearenergy, and elongation at the break. When ranked by viscosity, the compounds appeared in the following order: silica> silica (Si-69) > organoclay > organoclay (Si-69) > carbon black. Fractional hysteresis, tensile set, and wear rateswere very consistent with the viscosity of the vulcanizates. The Si 69 coupling agent increased reversion resistance,the maximum torque values in the ODR, modulus, and wear resistance, but decreased elongation at the break, frac-tional hysteresis, and tension set of the vulcanizates.

Influence of a Stacked-CuPc Layer on the Performance of Organic Light-Emitting Diodes

copper phthalocyanine; molecular stacking; magnetic field; semiconductor material; OLED

Vacuum deposited copper phthalocyanine (CuPc) was placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in a multi-layered, organic, light-emitting diode (OLEDs). The well-stacked CuPc layer increased the stability and efficiency of the devices. Thermal annealing after CuPc deposition and magnetic field treatment during CuPc deposition were performed to obtain a stacked-CuPc layer; the former increased the stacking density of the CuPc molecules and the alignment of the CuPc film. Thermal annealing at about 100℃ increased the current flow through the CuPc layer by over 25%. Surface roughness decreased from 4.12 to 3.65 nm and spikes were lowered at the film surface as well. However, magnetic field treatment during deposition was less effective than thermal treatment. Eventually, a higher luminescence at a given voltage was obtained when a thermally-annealed CuPc layer was placed in the present, multi-layered, ITO/CuPc/NPD/Alq3/LiF/Al devices. Thermal annealing at about 100 oC for 3 h produced the most efficient, multi-layered EL devices in the present study.

유연한 곁가지를 가진 디아민으로부터 층상 구조의 폴리이미드 합성

polyimides; flexible side chains; segregated layered structure; molar volume

We have synthesized two types of diamine monomers containing various chain length to prepare polyimides with layered structure. By using these diamines, homo-polyimides and co-polyimides having hydrophobic and hydrophilic segment of flexible side chain were synthesized. The segregated layered structures were formed by repulsive force with main chain as the side chains reach a critical length because the rigid main chains are packed into layered structure with the flexible side chains occupying the space between layers. As a result, the gallery space of each homo-polyimide was increased at spacing of 32.7~48 Å or 7~10.5 Å as the increased hydrophobic or hydrophilic side chain length through X-ray diffraction. The gallery space of co-polyimides was also showed similar phenomenon by repulsive force of side chains with different properties. We have also confirmed that gallery space and molar volume were significantly depended on length of flexible side chain via molecular modeling.

Synthesis and Performance of Reactive Light Stabilizers for Weather-Resistant UV-Curable Coatings

UV curing; coatings; weather resistance; light stabilizer; acrylates

In this study we investigated whether the weathering performance of UV-curable coatings could be improved significantly by using both a reactive light stabilizer and an optimized photoinitiator combination. A reactive light stabilizer (UCHA) containing a UV absorbance group, a radical scavenger, and acryl groups in the same molecule was synthesized and its performance investigated. Experimental studies of the UV-curing kinetics indicated that a combination of Irgacure 819 and Darocure 1173, in a ratio of 1:3, provided the best performance and cost. The outdoor resistance of the coated films was tested in an accelerated QUV weatherometer; IR spectroscopy was used to monitor quantitatively the chemical changes that occurred during QUV irradiation. The exposure results obtained with UCHA showed that the UV-curable coatings are useful in outdoor applications.

Kinetics of Thermal Degradation of Waste Polypropylene and High-Density Polyethylene

thermal degradation; kinetics; waste PP; HDPE; thermogravimetric technique

A kinetic analysis of the thermal degradation of waste polypropylene (PP) and high-density polyethylene (HDPE) has been studied using a conventional thermogravimetric technique under a nitrogen atmosphere at several heating rates between 10 and 30 ℃/min. To obtain the kinetic parameters to describe the thermal degradation of waste PP and HDPE, dynamic thermogravimetric analysis curves and their derivatives were analyzed using a variety of analytical methods. The waste PP and HDPE samples were obtained from a recycling center for waste plastics. Our results suggest that the best methods for the kinetic analyses of the thermal degradation of waste PP and HDPE are the Dynamic and Friedman methods. In addition, we found that the activatino energy for a waste blend was smaller than those of waste PP and HDPE.

Formation and Characterization of Silica-Coated Magnetic Nanoparticles by Sol-Gel Method

silica-coated magnetic nanoparticles; co-precipitation method; sol-gel process; amino-silane coupling agent

Fe3O4 nanoparticles having a size of 10 nm were synthesized by the co-precipitation of Fe3+ and Fe2+ (molar ratio, 2:1) with NH4OH under a nitrogen atmosphere. The γ-Fe2O3 nanoparticles were also prepared by the sol-gel process using Fe(NO3)3ㆍ9H2O and ethylene glycol. The particle size of γ-Fe2O3 decreased upon decreasing of molar ratio R [Fe(NO3)3ㆍ9H2O/ethylene glycol]; the mean particle size was ca. 15~20 nm. Silica particles were coated on the surface of Fe3O4 and γ-Fe2O3 nanoparticles by the hydrolysis of TEOS, and then 3~APTES, an amino-silane coupling agent, was covalently coupled to the surface of the silica-coated magnetic nanoparticles. The characteristics of the silica-coated magnetic nanoparticles were analyzed by TEM, X-ray diffraction, TGA-DTA, and FT-IR spectroscopy. As a result, the structure of the magnetic nanoparticles was determined to be of the spinel type; the crystalline phase transition temperature from α-Fe2O3 to γ-Fe2O3 was ca. 400 ℃. In addition, Fe-O-Si chemical bonds appeared on the surface of the magnetic nanoparticles.

ZnO를 첨가한 PVC와 PS 혼합물의 열분해 특성에 관한 연구

pyrolysis; poly(vinyl chloride); polystyrene; ZnO

The co-pyrolysis characteristics of poly(vinyl chloride) (PVC) and polystyrene (PS) mixtures with ZnO have been studied by thermogravimetry (TG) and gas chromatograph-mass spectrometry (GC-MS) under various mixing ratios and reaction temperatures. From this work, it was found that the yield of liquid products increased as PS in mixtures increased, whereas that of gaseous products decreased. And as ZnO in mixtures increased, the yields of gaseous products and HCI decreased. The optimal reaction temperature for the maximum yield of liquids products and the control of HCI gas was 500 ℃.

광경화형 Dimethylol Propionic Acid 변성 하이퍼브랜치 아크릴레이트의 합성과 물성

hyperbranched; acrylate; photocurable; dimethylol propionic acid

Photocurable hyperbranched acrylates were prepared from acrylic acid and hyperbranched polyol (HBP-16, 32, 64). Physical properties of three kinds of photocurable hyperbranched acrylated were investigated. Thermal stability of UV cured film measured by TGA shifted to higher temperature with increasing of functionality of acrylate. Weathering test for UV cured film showed the value of yellow index increased with increasing functionality of acrylate.

상수도관 부식방지를 위한 탄산칼슘 포화지수(LI) 인자 제어에 관한 연구

LI; calcium carbonate saturation index; corrosion control; total alkalinity

Calcium Carbonate Saturation Index (LI: Langelier Index), an indicator of CaCO3(s) saturation, indicates corrosiveness of drinking water and it has been used to monitor drinking water conditions in USA, E.U, and Japan. The objective of this research was to measure LI parameters including water temperature, pH, total alkalinity, calcium ion concentration, and electric conductivity, and to evaluate possibility of using LI in domestic system. Results showed that water temperature varied from 2.0 to 26 ℃ during 15 months, indicating an average annual temperature of 23.9℃. Total alkalinity was from 20 to 26 ℃ during 15 months, indicating an average annual temperature of 23.9℃. Total alkalinity was from 20 to 45 mg/L. The concentration difference between total alkalinity and HCO3- value was hardly observed; the concentration of total alkalinity can be replaced by that of HCO3- Tap water had a medium corrosiveness since LI values were from 2.0 to 0.5. To reduce the corrosiveness and to increase LI values of drinking water, the results of this study showed that chemicals such as Ca(OH)2, CaCO3, NaOH, or NaHCO3 should be added to water treatment plants.

PVC와 ABS 혼합물의 공열분해에 대한 금속산화물의 첨가 효과

PVC; ABS; CaO; Cu2O; pyrolysis

The co-pyrolysis characteristics of polyvinylchloride (PVC) and acrylonitrile butadiene styrene (ABS) mixtures with various mixing ratios and effect of addition of CaO and Cu2O have been studied using thermogravimetry (TG) and gas chromatograph-mass spectrometry (GC-MS). In an isothermal decomposition conducted at 500 ℃, the yields of styrene monomers and aromatic compounds increased as the mixing ratio of ABS increased, and the yield of BTX compounds reached its maximum (16.14%) when the mixing ratios of PVC and ABS was 4:1. In an isothermal decomposition added with metal oxides, the maximum yield of liquid product was 73% when CaO [CaO/(PVC+ABS)=0.4] was added and it was 70% when Cu2O [Cu2O/(PVC+ABS)=0.4] was added, respectively, where HCI contained in the gaseous product was completely removed when added with CaO [CaO/(PVC+ABS)=0.5] and Cu2O [Cu2O/(PVC+ABS)=1.0]. Therefore, to obtain the highest yield of liquid product it appears to be the reaction condition: the reaction temperature of 500 ℃ and mixing ratios of CaO and Cu2O are 0.5 and 1.0, respectively.

광경화형 Dipentaerythritol 변성 폴리메타아크릴레이트의 합성과 물성

UV; polyacrylate; photocurable; dipentaerythritol; trimellitic anhydride

Photocurable modified 6 functional polyacrylate(PA-1) were prepared from dipentaerythritol derivatives (DPET) and acrylic acid, and 12 functional polymethacrylate(PA-2) were prepared from dipentaerythritol derivatives (DPET), trimellitic anhydride, and glycidyl methacrylate. And physical properties of photocurable modified poly(meth)acrylate were increased with increasing functionality of (meth)acrylate. Thermal stability of UV cured film obtained by using TGA was shifted to higher temperature as the increasing of functionality. Hardness, abrasion resistance and tensile strength of UV cured film were increased with increasing functionality of (meth)acrylate. Values of yellow index were increased with increasing functionality of (meth)acrylate.

광경화형 폴리에스터 폴리올 변성 하이퍼브랜치 메타아크릴레이트의 합성과 물성

hyperbranched; acrylate; photocurable; polyester polyol

8 functionality photocurable polyester polyol modified hyperbranched methacrylates of two types were prepared from trimellitic anhydride, glycidyl methacrylate, and 4 functionality polyester polyol of two types. The physical properties of photocurable polyester polyol modified hyperbranched methacrylate were investigated. Thermal stability obtained by using TGA showed that HBMA-2 (hyperbranched methacrylate-2) was superior to the HBMA-1 (hyperbranched methacrylate-1). Hardness, abrasion resistance and tensile strength of HBMA-2 showed that were also superior to the HBMA-1. Value of yellow index of HBMA-2 showed the higher.

Modified Fenton Reaction과 Fenton-like Reaction을 이용한 화약류 오염 토양/지하수의 처리에 관한 연구

Modified Fenton Reaction; Fenton-Like Reaction; TNT; Chelating Agents; Neutral pH

There have been large areas of soil contaminated with high levels of explosives. For this experimental work, 2,4,6-trinitrotoluene (TNT) was tested as a representative explosive contaminant of concern in both aqueous and soil samples and its removal was evaluated using three different chemical treatment methods: 1) the classical Fenton reaction which utilizes hydrogen peroxide (H2O2) and soluble iron at pH less than 3; 2) a modified Fenton reaction which utilizes chelating agents, H2O2, and soluble iron at pH 7; and 3) a Fenton-like process which utilizes iron minerals instead of soluble iron and H2O2, generating a hydroxyl radical. Using classic Fenton reaction, 93% of TNT was removed in 20 h at pH 3 (soil spiked with 300 mg/L of TNT, 3% H2O2 and 1mM Fe(III)), whereas 21% removed at pH 7. The modified Fenton reaction, using nitrilotriacetic acid (NTA), oxalate, ethylenediaminetetraacetic acid (EDTA), acetate and citrate as representative chelating agents, was tested with 3% H2O2 at pH 7 for 24 h. Results showed the TNT removal in the order of NTA, EDTA, oxalate, citrate and acetate, with the removal efficiency of 87%, 71%, 64%, 46%, and 37%, respectively, suggesting NTA as the most effective chelating agent. The Fenton-like reaction was performed with water contaminated with 100 mg/L TNT and soil contaminated with 300 mg/L TNT, respectively, using 3% H2O2 and such iron minerals as goethite, magnetite, and hematite. In the goethite-water system, 33% of TNT was removed at pH 3 whereas 28% removed at pH 7. In the magnetite-water system, 40% of TNT was removed at pH 3 whereas 36% removed at pH 7. In the hematite-water system, 40% of TNT was removed at pH 3 whereas 34% removed at pH 7. For further experiments combining the modified Fenton reaction with the Fenton-like reaction, NTA, EDTA, and oxalate were selected with the natural iron minerals, magnetite and hematite at pH 7, based on the results from the modified Fenton reaction. As results, in case magnetite was used, 79%, 59%, and 14% of TNT was removed when NTA, oxalate, and EDTA used, respectively, whereas 73%, 25%, and 19% removed in case of hematite, when NTA, oxalate, and EDTA used, respectively.

Photopolymerization of Thermoplastic Polyurethane/Acrylate Blends

Photopolymerization; Thermoplastic Polyurethane; Diffusion Control Reaction; IPNs; Phase Separation

The kinetics of photopolymerization of thermoplastic polyurethane/acrylate blends have been studied using Real Time - Fourier Transform Infrared Spectroscopy (RT-FTIR). The polymerization rate curves were autocatalytic in nature at the initial stage of reaction; then a retardation of the reaction conversion occurred gradually as the polymer matrix became vitrified and the reaction became diffusion controlled. A kinetic rate equation with a diffusion control factor term has been employed to characterize the diffusion-controlled reaction behavior. As the reaction conversion reaches the transition point, at which the maximum value of kp/kt 0.5 in the rate expression is obtained, the reaction becomes to be controlled by diffusion due to the restricted mobility of acrylate macromonomers, resulting in the rapid drop of the polymerization rate even keeping the same reactivity of all the double bonds of acrylate macromonomers. Interpenetrating polymer networks (IPNs) of thermoplastic polyurethane/acrylate systems were formed in the limit of TPU content in the formulations. As the content of thermoplastic polyurethane increased, the polymerization rate increased in the early stage of cure reaction. Blends containing polyurethane up to 30 phr have single glass transition temperature, which indicates that they are miscible in blends and no phase separation has been observed.

Cure Kinetics and Mechanical Properties of the Blend System of Epoxy/Diaminodiphenyl Sulfone and Amine Terminated Polyetherimide-Carboxyl Terminated Poly(butadiene-co-acrylonitrile) Block Copolymer

Epoxy; Amine; AB Block Copolymer; Kinetics; Toughness

.The cure kinetics of blends of epoxy resin (4,4'-tetraglycidyl diaminodiphenyl methane; TGDDM)/curing agent (diaminodiphenyl sulfone; DDS) with ATPEI (amine terminated poly-etherimide) - CTBN (carboxyl terminated poly (butadiene-co-acrylonitrile)) block copolymer (AB type) were studied using differential scanning calorimetry under isothermal conditions to determine the reaction kinetic parameters such as activation energy and reaction constants. Final cure conversion decreased with increasing amount of AB in the blends. A diffusion controlled reaction was observed as the cure conversion increased, and the curing reaction was successfully analyzed by incorporating the diffusion control term in the rate equation for the epoxy/DDS/AB blends. The fracture toughness was improved to about 350% compared to that of the unmodified resin at 30% of AB block copolymer. This is attributed to the formation of co-continuous morphology between the epoxy phase and AB block copolymer phase. By increasing the amount of AB, the modulus of the cured blends decreased, which was due to the presence of CTBN rubbery phases.

Dynamics of the Wet-end Section in Paper Mills

Bone-dry Weight; Consistency; Dynamic Model; Paper Mill; Retention; Linearization; Wet-end

A model representing the wet-end section of a paper mill has been developed to characterize its dynamic behavior during the grade change. The model is based on the mass balance relationships written for the simplified wetend white water network. From the linearization of the dynamic model, higher-order Laplace transfer functions were obtained followed by the reduction procedure to give simple lower-order models in the form of 1st-order or 2nd-order plus dead times. The dynamic response of the wet-end is influenced both by the white water volume and by the level of wire retention. Effects of key manipulated variables such as the thick stock flow rate, the ash flow rate and the retention aid flow rate on the major controlled variables were analyzed by numerical simulations. The simple dynamic model developed in the present study can be effectively used in the operation and control.

Stress-Strain Behavior of the Electrospun Thermoplastic Polyurethane Elastomer Fiber Mats

thermoplastic polyurethane elastomer (TPUe); electrospinning; mechanical behavior; morphology

Thermoplastic polyurethane elastomer (TPUe) fiber mats were successfully fabricated by electrospinning method. The TPUe fiber mats were subjected to a series of cycling tensile tests to determine the mechanical behavior. The electrospun TPUe fiber mats showed non-linear elastic and inelastic characteristics which may be due to slippage of crossed fiber (non-bonded or physical bonded structure) and breakage of the electrospun fibers at junctions (point-bonded or chemical bonding structure). The scanning electron microscopy (SEM) images demonstrated that the point-bonded structures of fiber mats played an important role in the load-bearing component as determined in loading-unloading component tests, which can be considered to have a force of restitution.

The Solid-Phase Synthesis of Amino Acid-Derived Diacetylene Lipids

solid-phase synthesis; diacetylene; amino acids

We prepared amino acid-derived diacetylene monomers using solid-phase organic synthesis. The solidphase synthetic method allowed for the rapid and efficient preparation of functional diacetylenes. Amino acids having hydrophobic sidechains such as alanine, leucine, and phenylalanine, as well as hydrophilic sidechains such as aspartic acid and lysine, were successfully coupled to the diacetylene lipid. The diacetylene monomers prepared in this way were subjected to routine procedures for the generation of polydiacetylene vesicles. Depending on the nature of the side-chains, pink to blue colored polydiacetylenes were generated.

변성 폴리에테르이미드의 합성과 이를 이용한 에폭시 수지의 강인화

modified polyetherimide; epoxy resin; fracture toughness

Amine terminated polyetherimide (AT-PEI) has been synthesized using 2,2'-bis[4-(3,4-dicarboxyphenoxy)-phenyl]propane dianhydride (BPADA) and m-phenylenediamine. Polyetherimide containing pendant carboxy group (CP-PEI) has also been synthesized by the reaction of BPADA, m-phenylenediamine and 3,5-diaminobenzoic acid. The modified PEIs were used as toughening agent for diglycidyl ether of bisphenol-A epoxy resin which was cured with nadic methyl anhydride (NMA). Thermal properties, fracture toughness (KIC) and solvent resistance of toughened epoxy resin were measured. The KIC of epoxy resin containing 20 phr of AT-PEI was 2.88 MPaㆍm0.5 without sacrificing thermal properties. The KIC of epoxy resin which contained 20 phr of CP-PEI was 2.82 MPaㆍm0.5.

광경화형 Pentaerythritol 변성 초분지형 아크릴레이트의 합성과 물성

hyperbranched; methacrylate; photocurable; pentaerythritol

Photocurable pentaerythritol modified hyperbranched acrylates were prepared from trimellitic anhydride, glycidyl methacrylate and pentaerythritol derivatives. Thermal stability obtained by using TGA showed that HBMA-1 was superior to others. Hardness, abrasion resistance and tensile strength of HBMA-1 showed that they were also superior to the others. Value of yellow index of HBMA-1 showed the lowest.

Growth Mechanism of Nano-sized Titania-coated Silica Particles Prepared from Metal Alkoxide in a Nonionic Water-in-Oil Microemulsion

TiO₂-coated SiO₂; W/O microemulsion; growth mechanism; chronomal analysis

Nielsen's chronomal analysis was applied to clarify the growth mechanism of TiO₂ particles coated on SiO₂ core nanoparticles. In this study, SiO₂ nanoparticles and TiO₂-coated SiO₂ nanoparticles were synthesized by the hydrolysis of TEOS and TEOT, respectively, using a water-in-oil (W/O)-type microemulsion method. Firstly, SiO₂ nanoparticles 17-nm size were obtained by controlled hydrolysis of TEOS solutions, and then the SiO₂ particles in the microemulsion were allowed to coat and grow by the further addition of TEOT as a precursor of the TiO₂ particles. Considering the chronomal analysis, it was assumed that the particle growth mechanism was a surface reaction in which the rate-limiting step was a first-order polynuclear layer growth mechanism and the growth rate constant, k_p, was about 6.06X10^-8 cm/sec.

Thermal Properties of Polydisperse Oloigo(Propylene Oxide-Block-Ethylene oxide) Allyl (Methyl) Ether Surfactants Containing Polysiloxane Backbone

polydisperse PA-ohgo(PO-b-EO) allyl (methyl) ether siloxane surfactants; weight-loss temperature; phase transition temperature; methoxy group

Polydisperse PA-oligo(PO-b-EO) allyl (methyl) ether siloxane surfactants [PA-oligo(PO-b-EO) and PA-oligo(PO-b-EO)Me series] were synthesized by the hydrosilylation reaction. To observe the thermal properties of the PA-oligo(PO-b-EO) allyl (methyl) ether siloxane surfactants, the phase transition temperature (cloud point: C_p) and weight-loss temperature were measured by using a thermal optical analyzer (TOA) and a thermal gravimetric analyzer (TGA). The values of the weight loss temperature and C_p of the PA-oligo(EO) and PA-oligo(EO)Me series increased upon increasing the EO chain length. Also, the weight-loss temperature of the PA-oligo(EO)Me series was higher than that of the PA-oligo(EO) series, and the values of C_p of the PA-oligo(EO)Me series were lower than those of the PA-oligo(EO) series because of the presence of the methoxy group (-OCH₃). The values of C_p of the PA-oligo(PO-b-EO) and those of the PA-oligo(PO-b-EO)Me series decreased as the PO ratio, and the values of C_p of PA-oligo(PO-b-EO)Me were lower than those of the PA-oligo(PO-b-EO) series because of the existence of the methoxy group. However, the weight-loss temperature of the PA-oligo(PO-b-EO) and PA-oligo(PO-b-EO)Me series tended to increase with the PO ratio because the molecular weights of the PA-oligo(PO-b-EO) allyl (methyl) ether siloxane surfactants increased according to the increasing content of the PO unit.

Numerical Analysis of Turbulent Gas-Particle Flow and Coal Combustion in a Fluidized-Bed Calciner

fluidized-bed calciner; FLUENT; three-dimensional numerical analysis

In this paper, we analyze numerically the characteristics of turbulent gas-particle flow, heat transfer, and coal combustion process in a fluidized-bed calciner for a cement manufacturing process. The simulation model was based on FLUENT, a commercially avaliable fluid dynamics code. The effects of the mutual interactions between particles were simulated by a discrete phase modeling approach, while the decomposition of calcium carbonate into calcium oxide and carbon dioxide upon heating was handled by a finite-rate reaction modeling approach. To verify the validity of the numerical simulation approach used in this work, the simulation results were compared with field data, for example, the gas velocity and temperature in some sampling points. The simulation results showed comparatively good correlations with the field data.

RPF (Refused Plastics Fuel)를 이용한 활성탄의 제조 및 특성

activated carbon; RPE; adsorption; porosity; oxidation

Activated carbon is the nonpolar containing carbon, activated by the steam (vapor) or chemicals. It is porous amorphous carbon that can be used in many fields of industry as the materials for decolorization, deodorization, recovery, separation, scavenging and so on. Until now, there are various types of raw materials to make activated carbon: chartype like woods, coconut and coal type like lignite, and hard coal. Thermoplastics can not be used to make activated carbon because the high volatile matter in them prevents char formation. For the case of thermoplastic aromatic polymer RPE (Refused Plastics Fuel), fabrication of activated carbon can be achieved using an aromatic polymer's special property, such as forming graphite structure. Activated carbons from EI (polyetherimide) showed high porosity in proportion to the high porosity. There were suprising results of high porosity and adsorption character, because nitricacid oxidation pretreatment offered an advantage of making more activation sites that gave such good porosity. Optimized conditions for the fabrication process of the activated carbon from such aromatic polymer as polyetherimide can be established as follows; carbonization temperature 750 ℃, activation temperature 950 ℃ and activation time 3 hr.

Carboxylic Ester Acrylate를 이용한 광경화형 에폭시 아크릴레이트의 합성과 물성

epoxy acrylate; photocurable; 2-hydroxyethyl acrylate; anhydride

A variety of carboxylic ester acrylates was prepared from anhydrides and 2-hydroxyethyl acrylate. Photocurable epoxy acrylates were prepared from synthesized carboxylic ester acrylates and 1,4-butanediol diglycidylether. Physical properties such as hardness, yellowing, tensile strength and elongation were tested and compared as the structure of oligomer in cured-film differs. Viscosity was highest when phthalic anhydride was used. Hardness and tensile strength with hexahydrophthalic anhydride were better than with the other anhydrides. Glass transition temperature with hexahydrophthalic anhydride was higher than with the others. And 5% weight loss temperature with hexahydrophthalic anhydride was higher than with the others.

폴리이미드 블록공중합체를 사용한 에폭시 수지의 강인화 연구

PI-CTBN-PI block copolymer; toughening; epoxy resin; fracture toughness

PI-CTBN-PI block copolymer and PI-CTBN block copolymer were obtained thru the reaction of amine terminated polyetherimide (PI) and carboxyl terminated butadiene-acrylonitrile copolymer (CTBN). These block copolymers were used as a toughening agent for diglycidyl ether of bisphenol-A epoxy resin that was cured with nadic methyl anhydride (NMA). Thermal properties, fracture toughness (K_IC) and solvent resistance of toughened epoxy resin were measured. The K_IC of epoxy resin toughened with 20 phr of PI-CTBN-PI block copolymer was 3.12 MPaㆍm^0.5 while that of neat epoxy resin was 1.36 MPaㆍm^0.5. Due to the phase separation and the good interfacial adhesion of terminal amine group, the fracture toughness was considered to have increased.

황화수소 제거를 위한 SiC 지지체의 산화철 흡수제 개발

H₂S; IGCC; SiC; iron oxide; antimony oxide

To develop a suitable sorbent for HGD (hot gas desulfurization) process, this study employed SiC(silicon carbide) as a support material that can improve the strength and durability of iron oxide sorbent. Further, for synergic effect and direct recovery of sulfur, the sorbent was added with Sb₂O, which has gone through the steps of calcination and oxalic acid treatment, thus producing FeSbO₄ compound. The properties of the prepared sorbents were analyzed via BET, XRD and SEM, and optimum calcination temperature, contents of additives, contents of iron oxide, and reaction temperature were also investigated by TGA and GC. The above experiments revealed that porous supports were produced via sintering, and oxidization of the surface of the supports led to increase in bonding strength among the active ingredients thereby improving both durability and stability. In addition, the sulfidation/regeneration reaction at 600 ℃ showed the desulfurization ability of 18%, which is much higher than that of the standard commercial sorbent of 10%, and crush strength was improved to about 13% when there was an increase of 20% in the content of support.

H₂S 제거를 위한 철광석계 탈황제에 대한 첨가물 효과

H₂S; IGCC; sorbent; iron oxide; antimony oxide

To reduce H₂S in the gas stream of IGCC process, the H₂S sorption capacities of iron-based sorbents were examined at the temperature range of 400 ~ 600 ℃ in a lab scale fixed-bed reactor. The prepared sorbents were characterized by XRD, SEM, TGA, BET and mercury porosimetry. The H₂S sorption capacities of sorbents increased with the temperature of sulfidation reaction but decreased above 600 ℃ due to the instability of sorbents. The effect of additives such as Sb₂O₃ and NiO were investigated. Among them Sb₂O₃ additive showed relatively higher H₂S sorption capacity. The optimum weight ratio of Sb₂O₃/iron ore turned out to be about 0.03.

광경화형 지방족 에폭시 변성 우레탄 아크릴레이트의 합성과 물성

photocurable; aliphatic epoxy acrylate; aliphatic epoxy modified urethane acrylate; diisocyanate

A photocurable aliphatic epoxy modified by urethane acrylate was prepared from BDGEDA, NPGEDA and the diisocyanate in order to improve the properties of an aliphatic epoxy acrylate. After mixing a photoiniatiator, the curing properties of the photocurable aliphatic epoxy modified by urethane acrylate were investigated. The viscosities of NUA were higher than BUA. The glass transition temperatures of NUA were higher than those of BUA, and NUA was thermally more stable than BUA. The hardness and abrasion of NUA were higher than those of BUA. The yellow index of both NUA and BUA showed a similar result but that of BUA was a little higher. NUA had higher tensile strength of UV cured-film than BUA, but BUA had a higher elongation than NUA.

광경화형 지방족 에폭시 아크릴레이트의 합성과 물성 (II)

aliphatic epoxy acrylate; photocurable; neopentylglycol diglycidyl ether; acrylic acid; reactive monomer

Photocurable aliphatic epoxy acrylate was prepared from acrylic acid and neopentylglycol diglycidyl ether that was obtained by reacting neopentylglycol with epichlorohydrin. After its dilution with three kinds of reactive monomers (2-hydroxyethyl acrylate, tri (propylene glycol) diacrylate, trimethylolpropane triacrylate) the properties of photocurable aliphatic epoxy acrylate were investigated. Their viscosities decreased with increasing the amount of reactive monomers, but increased when a higher functionality monomers were used. Glass transition temperature of UV-cured film obtained from tan peak by using DMA shifted to a higher temperature as the increase of monomer functionality while thermal stability exhibited similar behavior. Hardness, abrasion resistance, and tensile strength of UV-cured film also increased with increasing functionality of monomer, and elongation was reduced with the higher monomer functionality. In accelerlated weathering test, UV-cured film showed the value of yellow index increased with increasing functionality of monomer.

분해성 지방족 폴리에스테르 이오노머의 합성 및 물성 (I)

degradable; aliphatic polyester; ionomer; PBS; dimethyl-5-sulfoisophthalate sodium salt (DMS)

The environmentally friendly degradable aliphatic PBS and PBSDMS ionomers were synthesized in order to investigate the properties of these ionomers. Poly(butylene succinate - co - buthylene 5-sulfoisophthalate) (PBS ionomer) was prepared from succinic acid, 1,4-butanediol, and dimethyl 5-sulfoisophthalate sodium salt (DMS). In thermostability, PBSDMS ionomers showed a lower stability than PBS. The melting point and weight loss temperature of PBSDMS ionomers decreased slowly with increase of DMS content. On hydrolyzing polyesters in buffer solution, the hydrolysis rates of PBS and PBSDMS ionomers were very slow in acidic, neutral and pH 10 buffer solutions, but increased quickly in a pH 12 buffer solution. The contact angle of PBS and PBSDMS ionomers to water was also measured. PBSDMS ionomer's contact angles decreased slowly with the increase of DMS content.

H₂S 제거를 위한 철광석계 흡수제의 반응 특성 연구

H₂S; IGCC; Sorbent; iron oxide; phosphorus

To recude H₂S in the gas stream of IGCC process, the H₂S sorption capacities of iron-based sorbent were examined at the temperature range of 400 ~ 700 ℃ with lab scale fixed-bed reactor. The H₂S sorption capacities of sorbents increased with the temperature of sulfidation reaction but decreased above 600 ℃ due to the instability of sorbents. The effect of additives such as Cr₂O₃, MnO, Co₂O₃, Ni₂O₃ and phosphorus were investigated. Among them Co₂O₃ additive showed relatively higher H₂S sorption capacity. The optimum content content of phosphorus turned out to be about 2% although the H₂S sorption capacity decreased. During the 5-cycle sulfidation/regeneration reaction in the fixed-bed reactor, all sorbents studied here maintained 90% of the initial H₂S sorption capacity of their fresh samples.

골재소성용 로터리 킬른의 운전조건변화에 따른 현상예측을 위한 수학적 모델링

Rotary Kiln; CFD; Heat Transfer; Modeling

Rotary kilns are employed by industrial site to carry out a wide variety of material processings; calcining limestone, reduction of oxide ore,etc. In this study a mathematical model was developed to predict heat transfer from the freeboard gas to the bed of a rotary kiln. This presents a three-dimensional mathematical model to describe and simulate the calcination of solid bed in a rotary kiln. The model comprises conventional differential equations derived from the principles of conservation of mass and energy and this can be used to predict the temperature profiles of the solid bed, the gas phase and inner wall of the kiln along the length of the kiln axis and in radial direction. The major parameters considered here are kiln rotation rate(rpm), filling ratio of the solid bed, burner injection-temperature. The results from the simulation showed reasonable agreement with experimental results available in the literature.

막ㆍ전극접합체에서 함수율 분포의 직접계산을 위한 수학적 모델

PEFC; Modeling; Water Content; CFD

Water content is one of the critical factors in predicting physical and electrochemical phenomena in Membrane Electrode Assembly(MEA), which is a core element of polymer electrolyte fuel cell(PEFC). Water content directly affects on proton conductivity in MEA and is also a very important parameter in predicting current density distribution. To paraphrase, water content is a critical factor in predicting the performance of PEFC. Therefore, accurate prediction of water content distribution in MEA is important in PEFC modeling. In this paper, in order to directly calculate the water content distribution in MEA, we introduced a mathematical model, which is based on computational fluid dynamics, using internal boundary conditions and validated it by comparing with experimental data.

NH₃ 플라즈마 처리한 폴리스티렌 막에서 CO₂의 수착과 투과특성

Polystyrene Membrane; Plasma Treatment; Sorption; Permeation

The applicable possibility of dual-mode sorption/mobility model and the change of mean permeation coefficient as the change of the plasma input power were investigated from the sorption and permeation experiments of CO₂ in polystyrene membrane treated with NH3 plasma. The sorption experiment carried out using a pressure decay method and the permeation experiment carried out using a variable-volume method. The sorption and permeation behavior of CO2 were simulated well in terms of the dual-mode sorption and mobility model. The mean permeation coefficient was decreased under 80 W of the plasma input power but increased above 80 W of the plasma input power.

플라즈마 디스플레이 패널(PDP)의 방전과 열화공정에 따른 표면으로부터의 기상특성

Plasma Display Panel; Aging; XPS; MgO; Phosphor

Plasma display panel(PDP) uses the mixture of inert gases to generate a discharge inside display pixels. Inside of PDP, there exists highly reactive conditions in the gap between two glass panels. Chemical properties of MgO layer and phosphor have been investigated as a function of discharge and thermal process. Impurities such as CO, CO₂, OH and H₂O in discharge region may deteriorate the characteristics of PDP operation during life time. Change of impurity generation of various MgO and phosphor surfaces were measured by using x-ray photoelectron spectroscopy (XPS) and quadropole mass spectrometer (QMS). Concentrations of carbon containing species such as C, CO and CO₂ were drastically increased from surfaces during discharge and thermal treatment. Carbon impurities on the MgO and phosphor are the dominant factor for their instability.

Seed와 수용성 고분자를 사용한 화학적 환원법을 이용한 은 나노와이어의 합성

Silver Nanowires; Chemical Reduction; Polyol Process; Capping Agents; Nanoparticles; Polyvinylpyrrolidone(PVP); Five-Twinned Structure

Silver (Ag) nanowires with five-twinned structure were synthesized by chemical reduction method through the polyol process, in the presence of capping agents. The obtained silver nanowires are well-high monodispersed with the average diameter of 80 nm and length of 50 μm. Micro-scopical structures in these nanowires could be varied from nanoparticles and nanorods to nanowires by controlling the reaction conditions such as reaction temperature, molecular weight of PVP, kinds of seed materials, and changes of liquid polyols. Nanoparticles of platinum groups play roles of seed materials for the heterogeneous nucleation and growth of silver because of their close fitness in crystal structure and lattice constant. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD) and UV-visible spectroscopy were used to characterize silver nanowires.

실시간 In-situ IR분광법을 이용한 Isophorone Diisocyanate(IPDI)와 Dimethylol Alkanoic Acid계 폴리우레탄 프리폴리머의 반응 속도론 연구

Real Time In-situ IR Spectroscopy; Urethane Formation; Kinetics; Dimethylol Propionic Acid; Dimethylol Butanoic Acid; Water-Borne Polyurethane

Kinetics of pre-polymerization of polyurethane formation between isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) in solution state (IP reaction), and IPDI and dimethylol butanoic acid (DMBA) in solution state (IB reaction) were studied by using quantitative real-time in-situ IR spectroscopy at different temperatures in the range of 60-90 ℃ with [NCO]/[OH] ratio of 1.0. The reaction rate was obtained from monitoring the change of NCO (2,265 cm^-1) stretching band in series IR spectra. The reaction was in accord with the first-order for the concentrations of hydroxyl groups and isocyanate groups respectively, which conformed to the second order law entirely. The activation parameters were obtained from the evaluation of kinetic data as follows. For IP reaction, activation energy (E_a)=42.2 kJ/mol, activation enthalpy (ΔΗ^‡)=39.3 kJ/mol and activation entropy (ΔH^‡)=-146.7 J/mol K. For IB reaction, E_a=36.9 kJ/mol, ΔH^‡=34.0 kJ/mol and ΔS^‡=-163.3 J/mol K.

폴리에틸렌옥사이드계 고체 고분자전해질의 특성에 미치는 과불화폴리에테르 첨가 효과

Perfluoropolyether; Solid Polymer Electrolytes; Lithium Polymer Battery; Thermal Property; Ionic Conductivity

We studied perfluoropolyether addition effect on the properties of poly(ethylene oxide)-based solid polymer electrolytes (SPE). PFPE/PEO PU prepared with 1/99, 5/95, 10/90, and 20/80 of PFPE/PEO wt. ratio. PFPE/PEO PU/LiCF₃SO₃ was prepared from lithium trifluoromethane sulfonate (LiCF₃SO₃). The glass transition temperatures (T_g) and melting temperatures (T_m) of PEO phases from differential scanning calorimetric analysis (DSC) were similar in salt-free PFPE/PEO PU series regardless of PFPE/PEO wt. ratio. In a series of PFPE/PEO PU/LiCF₃SO₃, T_g of PEO phase slightly increased with increasing PFPE contents. In both series of PFPE/PEO PU and PFPE/PEO PU/LiCF₃SO₃, the surface energies calculated by contact angle decreased with the increase of PFPE contents due to PFPE phase localized on the surface. Thermal stability from thermogravimetric analysis (TGA) was slightly decreased with increasing PFPE contents in both PFPE/PEO PU and PFPE/PEO PU/LiCF₃SO₃. Ionic conductivity of PFPE/PEO PU/LiCF₃SO₃ was slightly increased with the increase of PFPE contents.

폴리부틸렌테레프탈레이트/몬모릴로나이트 나노복합체의 결정화 거동 및 동적 기계적 물성에 관한 연구

Poly(butyleneterephthalte) Terephthalate; Montmorillonite; Nanocomposite; Non-isothermal Crystallization; Modified Avrami Analysis; Dynamic Mechanical Properties

Poly (butyleneterephthalate) (PBT)/montmorillonite (MMT) hybrid nanocomposite was prepared via melt intercalation using a co-rotating twin screw extruder. From the analysis using X-ray diffraction (XRD) and transmission electron microscope (TEM), it was confirmed that the PBT/MMT hybrid forms an intercalated structure in which MMT particles are partially exfoliated and are dispersed uniformly in the PBT matrix. The effect of clay layers on the non-isothermal crystallization behaviors of PBT was investigated by differential scanning calorimetry (DSC), and modified Avrami analysis was used for the interpretation of the results. It was found that the introduction of nano-size clay layers accelerates the non-isothermal crystallization process of PBT and the clay layers act as nucleating agents. Dynamic mechanical analysis for the nanocomposite showed that storage modulus of the PBT matrix was increased by more than 40% over whole temperature range on the addition of MMT by 5 wt%, but the change in glass transition temperature was marginal.

수화된 백운석을 이용한 SO₂의 건식 제거

Dolomite; Sulfur Dioxide; Ultrasonic Wave; Hydrated Sorbent

Domestic dolomite sorbents for the SO₂ removal were prepared and the characteristics of sorbents were investigated by TGA, XRD, SEM and BET. To improve SO₂ capture capacity, the dolomite sorbents were calcined, hydrated and recalcined at various conditions. The specific surface area of hydrated sorbents increased with increasing stirring rate, hydration temperature and hydration time. In this work, the hydration process by using ultrasonic wave was conducted at the hydration temperature of 100 ℃ for the hydration time of 100-120 min. The specific surface area of sorbent hydrated at the above condition, was increased by 25%, compared to that of unhydrated sorbent and the hydrated sorbent exhibited SO₂ removal capacity of 16 times higher than unhydrated sorbent. The effect of particle size for the sulfidation was examined. As a result, the highest SO₂ removal capacity could be achieved at the particle size of 32-60 μm. The SO₂ removal capacity of sorbent below 32 μm decreased due to sintering at about 850 ℃.

미분열중량곡선의 극점 특성치를 이용한 HDPE 열분해 동역학변수 결정에 대한 연구

Pyrolysis Kinetics; HDPE (High Density Polyethylene); Peak Property Method

This research was designed to determine the pyrolysis kinetic parameters of HDPE using Peak Property Method (PPM) which was recently developed. The properness of PPM was verified by comparing theoretical Derivative Thermogravimetry (DTG) curve with experimental one. The kinetic parameters derived from PPM was compared with those estimated from typical analysis methods and those reported by previous studies. The PPM was developed based on the assumption that a specific pyrolysis reaction would be characterized by three peak properties of DTG curve: peak temperature, peak height, and conversion at peak temperature. The activation energy, pre-exponential factor, and reaction order of HDPE pyrolysis reaction, respectively, were 251.92 kJ/mol, 1.70 × 10¹⁷ min^-1, and 0.581, demonstrating good agreement with those estimated by DTG curve fitting method[1]. The PPM simulates experimental DTG curve excellently and it was proved that the three peak properties of DTG curve would be enough to represent a unique thermal reaction. The pyrolysis kinetic parameters would be estimated easily but accurately by the PPM. However, the PPM is only applicable for a reaction which is represented by a conversion function of power law equation.

Numerical Methodology for Proton Exchange Membrane Fuel Cell Simulation using Computational Fluid Dynamics Technique

PEMFC; CFD; Modeling

To analyze the physical phenomena occurring in the Proton Exchange Membrane Fuel Cell (PEMFC) using Computational Fluid Dynamics (CFD) technique under an isothermal operating condition, four major governing equations such as continuity equation, momentum conservation equation, species transport equation and charge conservation equation should be solved. Among these governing equations, using the interfacial boundary condition is necessary for solving the water transport equation properly since the concept of water concentration in membrane/electrode assembly (MEA) and other regions is totally different. It was first attempted to solve the water transport equation directly in the MEA region by using interfacial boundary condition; and physically-meaningful data such as water content, proton conductivity, etc. were successfully obtained. A detailed problem-solving methodology for PEMFC is presented and result comparison with experimental data is also implemented in this paper.

Preparation of Anthracene Fine Particles by Rapid Expansion of a Supercritical Solution Process Utilizing Supercritical CO₂

Supercritical Fluid; RESS; Fine Particles; Anthracene

The rapid expansion of a supercritical solution (RESS) process is an attractive technology for the production of small, uniform and solvent-free particles of low vapor pressure solutes. The RESS containing a nonvolatile solute leads to loss of solvent power by the fast expansion of the supercritical solution through an adequate nozzle, which can cause solute precipitation. A dynamic flow apparatus was used to perform RESS studies for the preparation of fine anthracene particles in pure carbon dioxide over a pressure range of 150-250 bar, an extraction temperature range of 50-70 ℃, and a pre-expansion temperature range of 70-300 ℃. To obtain fine particles, 100, 200 and 300 μm nozzles were used to disperse the solution inside of the crystallizer. Both average particle size and particle size distribution (PSD) were dependent on the extraction pressure and the pre-expansion temperature, whereas extractor temperature did not exert any significant effect. Smaller particles were produced with increasing extraction pressure and preexpansion temperature. In addition, the smaller the nozzle diameter, the smaller the particles and the narrower the PSD obtained.

Modeling of the Drying Process in Paper Plants

Paper Mill; Drying Cylinder; Heat Transfer Coefficient; Simulation; Bone-dry Weight

In this study a model for the drying process in paper production plants was developed based on the mass and heat balances around drying cycles. Relationships for the heat transfer coefficients between the web and the air as well as between the drying cylinder and the web were extracted from the closed-loop plant operation data. It was found that the heat transfer coefficients could be represented effectively in terms of moisture content, basis weight and reel velocity. The effectiveness of the proposed model was illustrated through numerical simulations. From the comparison with the operation data, the proposed model represents the paper plant being considered with sufficient accuracy.

Modeling and Simulation of Wet-end White Water System in the Paper Mill

Bone-dry Weight; Consistency; Dynamic Model Paper Mill Retention Simulation Wet-end

A dynamic model representing the wet-end of a paper mill is developed to characterize its dynamic behavior. The model is based on the mass balance relationships written for the simplified wet-end white water network. The dynamic response of the wet-end is influenced both by the white water volume and by the level of wire retention. Effects of key manipulated variables such as the thick stock flow rate, the ash flow rate and the retention aid rate on the major controlled variables are analyzed by numerical simulations. It can be said that the consistency of the model with plant data seems to be reasonably good and can be used as a tool for plant analysis and control.

Synthesis and Characterization of ω-Sulfonated Polystyrene-stabilized Cadmium Sulfide Nanoclusters

cadmium sulfide; chain-end sulfonation; nanoclusters; semiconductor; ω-sulfonated polystyrene

We report an important and useful method for preparing ω-sulfonated polystyrene-stabilized cadmium sulfide (CdS) nanoclusters. The ω-sulfonated polystyrene (M_n = 5000 g/mol) was prepared successfully through chain-end sulfonation of poly(styryl)lithium using 1,3-propanesultone; the resulting polymer was used successfully as a polymeric stabilizing agent for the preparation of semiconductor CdS nanoclusters by reduction of cadmium acetate in a mixture of toluene and methanol (9:1, v/v). The nanoclusters that formed were characterized by a combination of transmission electron microscopy, X-ray diffraction, and UV/Vis spectroscopic analysis. The ω-sulfonated polystyrene-stabilized CdS nanoclusters synthesized in this study exhibited the cubic phase (zinc-blende phase) structure in the range of 2~8 nm.

Fabrication of Photoimageable Silver Paste for Low-Temperature Cofiring Using Acrylic Binder Polymers and Photosensitive Materials

photoimageable; silver paste; low-temperature cofiring; thick-film photolithography; fine-line resolution

Thick-film photolithography is a new technology that combines lithography processes, such as exposure and development, with the conventional thick-film process applied to screen-printing. In this study, we developed a low-temperature cofireable silver paste applicable for thick-film processing to form fine lines using photolithographic technologies. The optimum paste composition for forming fine lines was investigated. The effect of processing parameters, such as the exposing dose, had on the fine-line resolution was also investigated. As the result, we found that the type of polymer and monomer, the silver powder loading, and the amount of photoinitiator were the main factors affecting the resolution of the fine lines. The developed photoimageable silver paste was printed on a low-temperature cofireable green sheet, dried, exposed, developed in an aqueous process, laminated, and then fired. Our results demonstrate that thick-film fine lines having widths < 20 μm can be obtained after cofiring.

Kinetics of Acrylamide Solution Polymerization Using Potassium Persulfate as an Initiator by in situ IR

acrylamide; potassium persulfate; kinetics; in situ IR spectroscopy.

We have studied the polymerization kinetics of acrylamide in aqueous solution with potassium persulfate as an initiator by using quantitative real-time in situ IR spectroscopy and monitoring the profiles of peaks in the range 1900-850 cm^-1. The conversion of acrylamide was calculated from the disappearance of the peak at 988 cm^-1, which is the out-of-plane bending mode of the =C-H unit, normalized to the C=O stretching peak at 1675 cm^-1 as an internal standard. For reaction temperatures in the range 40-65 ℃ and initiator and monomer concentrations of 0.9-2.6 mmol/L and 0.5-1.1 mol/L, respectively, we deduced that the rate of monomer consumption follows the relation R_p = k[K₂S₂O₈]^0.5[M]^1.35±0.10. In addition, we obtained activation parameters from an evaluation of the kinetic data.

A Low-Viscousity, Highly Thermally Conductive Epoxy Molding Compound (EMC)

low viscosity; high thermal conductivity; AlN; fused silica; EMC.

Advanced epoxy molding compounds (EMCs) should be considered to alleviate the thermal stress problems caused by low thermal conductivity and high elastic modulus of an EMC and by the mismatch of the coefficient of thermal expansion (CTE) between an EMC and the Si-wafer. Though AlN has some advantages, such as high thermal conductivity and mechanical strength, an AlN-filled EMC could not be applied to commercial products because of its low fluidity and high modulus. To solve this problem, we used 2-μm fused silica, which has low porosity and spherical shape, as a small size filler in the binary mixture of fillers. When the composition of the silica in the binary filler system reached 0.3, the fluidity of EMC was improved more than twofold and the mechanical strength was improved 1.5 times, relative to the 23-μm AlN-filled EMC. In addition, the values of the elastic modulus and the dielectric constant were reduced to 90%, although the thermal conductivity of EMC was reduced from 4.3 to 2.5W/m-K, when compared with the 23-μm AlN-filled EMC. Thus, the AlN/silica (7/3)-filled EMC effectively meets the requirements of an advanced electronic packaging material for commercial products, such as high thermal conductivity (more than 2W/m-K), high fluidity, low elastic modulus, low dielectric constant, and low CTE.

Preparation and Properties of in situ Polymerized Poly(ethylene terephthalate)/Fumed Silica Nanocomposites

poly(ethylene terephthalate); nanocomposite; fumed silica; in situ polymerization.

We have prepared poly(ethylene terephthalate) (PET) nanocomposites filled with two different types of fumed silicas, hydrophilic (FS) and hydrophobic (MFS) silicas of 7-nm diameter, by in situ polymerization. We then investigated the morphological changes, rheological properties, crystallization behavior, and mechanical properties of the PET nanocomposites. Transmission electron microscopy (TEM) images indicate that the dispersibility of the fumed silica was improved effectively by in situ polymerization; in particular, MFS had better dispersibility than FS on the non-polar PET polymer. The crystallization behavior of the nanocomposites revealed a peculiar tendency: all the fillers acted as retarding agents for the crystallization of the PET nanocomposites. The incorporation of fumed silicas increased the intrinsic viscosities (IV) of the PET matrix, and the strong particleparticle interactions of the filler led to an increased melt viscosity. Additionally, the mechanical properties, toughness, and modulus of the nanocomposites all increased, even at low filler content.

하프-에스터 아크릴레이트를 이용한 광경화형 에폭시 변성 아크릴레이트의 합성과 물성

epoxy acrylate; photocurable; 2-hydroxyethyl acrylate; half-ester acrylate

Various half-ester acrylates were prepared from anhydrides and 2-hydroxyethyl acrylate. Photocurable epoxy modified acrylates were prepared from synthesized half-ester acrylate and neopentylglycol diglycidylether. Physical properties such as hardness, yellowing, tensile strength and elongation were tested and compared as the structure of oligomer in cured-film differs. It was found that viscosity of neopentylglycol diglycidylether-hexahydrophthalic anhydride (NP-HA) was highest. Hardness and tensile strength of photocrosslinked neopentylglycol diglycidylether-hexahydrophthalic anhydride were better than those of other photocrosslinked epoxy acrylates. And 5% weight loss temperature of photocrosslinked neopentylglycol diglycidylether-hexahydrophthalic anhydride was higher than those of other photocrosslinked epoxy acrylates. Value of yellow index of photocrosslinked neopentylglycol diglycidyl ether-succinic anhydride (NP-SA) was lower than the other products.

디메틸아크릴산 아연을 이용한 아크릴로나이트릴-부타디엔 고무 나노복합체의 제조 및 물성

nanocomposite; acrylonitrile-butadiene rubber; zinc dimethacrylate; mechanical property

Elastomeric nanocomposites were prepared by employing zinc dimethacrylate into an acrylonitrile-butadiene rubber, and their network structures, mechanical properties, and fracture morphologies were investigated according to the adding methods and contents of zinc dimethacrylate. The total crosslink density increased with increasing the zinc dimethacrylate level, due to increased ionic bonds. Both the tensile strength and tear strength increased with increasing zinc dimethacrylate loadings, and then decreased after reaching a maximum value. It was found that the tear strength and crack resistance were greatly affected by the mixing method of zinc dimethacrylate. The in-situ nanocomposites, where zinc dimethacrylate particles were formed by the reaction of zinc oxide and methacrylic acid, showed much improved tear strength and crack resistance compared to those of the nanocomposites based on the direct mixing of zinc dimethacrylate powders. This was because of the finer zinc dimethacrylate particles and improved dispersion of the in-situ nanocomposites.

폴리페닐렌옥사이드/에폭시 수지 블렌드의 경화거동 및 파괴인성에서 폴리페닐렌옥사이드가 미치는 영향

Tetrafunctional Epoxy Resin; Poly (Phenylene Oxide); Cure Behavior; Mechanical Interfacial Properties

In this work, the effect of poly (phenylene oxide) (PPO) in tetrafunctional epoxy resin (4EP) was investigated in terms of cure kinetics, thermal properties, and mechanical interfacial properties of the blends. The content of PPO was varied within 0, 5, 10, 15, and 20 phr to neat 4EP. The cure kinetics of 4EP/PPO blend system are examined by near-IR and DSC measurements. And the thermal stabilities were determined by initial decomposed temperature (IDT), thermal stability factors, and integral procedural decomposition temperature (IPDT) of the blends. For the mechanical interfacial properties of the casting specimens, the fracture toughness test was performed, and their fractured surfaces were examined by SEM. As a result, the conversion (α) is indicated in high value at 5 phr of PPO and, the cure activation energy (Ea) is decreased at 5 phr PPO, due to the plasticized PPO polymer molecule in epoxy resins. The thermal stabilities were increased, which can be explained by the presence of phenyl group of PPO in intermolecular chains. Also the fracture toughness parameters (KIC, GIC) show high values at 5 phr PPO. This result is interpreted in the development of interfacial adhesion force between intermolecules of the polymer chains.

아임계 및 초임계수하의 p-Xylene의 무촉매 부분 산화반응에서 반응조건이 Terephthalic acid의 선택성에 미치는 영향

Xylene; TPA; Supercritical; Oxidation

The possibility of manufacturing the terephthalic acid(TPA) by partial oxidation of p-xylene without a catalyst in subcritical and supercritical water medium was investigated experimentally. The effects of reaction conditions such as reaction temperature, pressure and hydrogen peroxide feed ratio on the conversion of p-xylene and the selectivity of TPA produced were investigated in batch reactor and new oxidation reaction pathway of p-xylene was proposed. Conversion of p-xylene was about 89.0% in subcritical condition and increased with the temperature increasing, over 99.0% in supercritical condition after 20 minutes from the start of reaction. The selectivity of TPA in subcritical conditions was higher than in supercritical conditions and the maximum value was 29.0% at 300 ℃, 220 bar, 50% H2O2 feed ratio. The pressure effect on TPA selectivity was higher at subcritical water condition than that at the supercritical condition.

W/O 마이크로 에멀젼법에 의한 SiO2 나노 입자의 제조에서 반응조건이 크기 및 입도분포에 미치는 영향

W/O; Microemulsion; SiO2; Nanoparticles

To synthesize silica nanoparticles, water, organic solvent(cyclohexane), ammonium hydroxide, and surfactant (NP-5) were used as a microemulsion, and then TEOS(TetraEthylOrthoSilicate) as a precursor of silica was added to the solution. The effect of reaction time, R(=water/surfactant) value, and ammonia concentration on particle size and size distribution was observed. As a result, the silica particles with nano size were prepared at the condition of 48 hrs reaction time. It was also found that the optimal conditions for R value and ammonia concentration were 25 and 0.1 M, respectively. Therefore, the silica nanoparticles(10-30 nm) with narrow size distribution(<±3.0%) were formed by the above optimal conditions.

The Contribution Rate of Coal-fired Power Plant Analyzed by CMB Modeling with Component Analysis Data of PM10

PM10; coal-fired power plant; CMB8 modeling

The purpose of this study is to analyze the contribution rate of air pollutants from Taean coal-fired power plants of four measuring points. For this purpose, total mass analysis, metal component analysis, ion component analysis, and carbon analysis were performed on particulate matter 10 (PM10) samples, collected over 24 h. In addition, to perform comparative analysis, data measured by the Ministry of Environment at Pado-ri, Taean-gun was also used. As a result of the analysis, at Pado-ri point, 15km away from the plant, Na⁺ and SO₄^2- accounted for 12%, respectively, occupying the biggest portion, while at the four neighboring points around the plant, organic carbon (OC) and elemental carbon (EC) accounted for up to 34.8%. The result of factor analysis performed by using SPSS 6 statistical package revealed that four measuring points around the plants have a correlation coefficient greater than 0.9. As a result of chemical mass balance (CMB) modeling, a receptor model, it was found to be the contribution rate of the power plants' four measuring points and standard error within 24% ~ 52% and 0.38 ~ 0.89 mg/m³, respectively. In detail, a-1 point (Hakam-po) showed the highest contribution ratio, while at a-2 point (Bangal-ri) contribution ratio of biomass burning (27%) was greater than that of emissions from the power plant (24%). In the next study, performing dispersion modeling on air pollutants from power plants and comparing this data with CMB 8 Modeling should be required, to locate pollutant sources and to establish an effective method of converting contribution ratio.

Thermal and Physical Properties of Oligo-(propylene oxide-block-ethylene oxide) Allyl Methyl Ether Containing Tetrasiloxane as Wetting Agent

wetting agents; OA-oligo(PO-b-EO)Me series; inorganic electrolyte; hydrolysis; siloxane backbone

Polydisperse oligo(propylene oxide-block-ethylene oxide) allyl methyl ether tetrasiloxane wetting agents [OA-oligo(PO-b-EO)Me series] were synthesized by hydrosilylation reaction of OMTS and allyl-oligo(PO-b-EO)Me series. Weight loss temperature and T_ps of OA-oligo(EO)Me series were increased due to the increase of EO chain length. When PO ratio was increased, T_ps of OA-oligo(PO-b-EO)Me series was decreased. However, weight loss temperature tended to increase according to the increase of PO ratio. Surface tension and wetting power of OA-oligo(EO)Me series were increased according to the increase of EO chain length. When PO ratio was increased, surface tension and wetting power of OA-oligo(PO-b-EO)Me series were decreased. As inorganic electrolyte was added, surface tension and sedimentation time of aqueous solutions tended to decrease due to the arrangement of surfactant molecules. Also, surface tension and sedimentation time of aqueous solutions were increased at pH 3 and 11 because of the hydrolysis of siloxane backbone.

Synthesis and Surface Active Properties of Trisiloxane Grafted Oligo (propylene oxide-block-ethylene oxide) Allyl Methyl Ether Surfactant

HA-oligo(PO-b-EO)Me series; hydrosilylation reaction; methoxylation reaction; arrangement; hydrolysis

1,1,1,3,5,5,5-heptamethyltrisoloxane (HMTS) grafted oligo(propylene oxide-block-ethylene oxide) allyl methyl ether [HA-oligo(PO-b-EO)Me] siloxane wetting agents were synthesized by hydrosilylation reaction of HMTS after methoxylation reaction of Allyl-oligo(PO-b-EO). Surface tension, wetting power, emulsion and foam stability of HA-oligo(PO-b-EO)Me series prepared by hydrosilylation reaction were observed. In the case of HA-oligo(EO)Me series, surface tension, wetting power, emulsion and foam stability tended to increase due to the increase of EO chain length. When PO ratio was increased, surface tension, wetting power, emulsion and foam stability of HA-oligo(PO-b-EO)Me series were decreased. When inorganic electrolyte was added surface tension of aqueous solution was decreased, and sedimentation rate tended to decrease more and more due to the; arrangement of surfactant molecules. Also, surface tension of aqueous solution was increased, and sedimentation rate was slow in pH 3 and 11 because of the hydrolysis of siloxane backbone. When toluene was used as oil in O / W system, emulsion stability was better than neat's foot oil.

Synthesis and Physical Properties of Oligo(propylene oxide-block-ethylene oxide) Allyl Methyl Ether

ethylene oxide; propylene oxide; allyl ether group; methylation; and phase transition behaviour

Oligo(propylene oxide-block-ethylene oxide) allyl methyl ethers (Allyl oligo(PO-b-EO) Me) with varying chain lengths and EO/PO ratios were synthesized using methylation, and addition reaction. Allyl oligo(PO-b-EO) with the reactive allyl end group was prepared by adding PO and EO using allyl alcoholate initiator ionized with KOH. Metallization was applied to the other hydroxy end using t-BuOK. Allyl oligo(PO-b-EO) Me was then synthesized by reacting this metallic anion with MeOTs of a good leaving group using SN2. These mono- and bi-substituted oligomers were identified using FT-IR, 1H-NMR, and GPC. They were then studied for the thermal properties and aqueous solution phase behaviors.

목재와 폴리프로필렌 혼합물의 열분해 특성에 관한 연구

pyrolysis; wood; polypropylene; heating rate; reaction temperature

The pyrolysis characteristics of wood and polypropylene(PP) mixtures have been studied by thermogravimetry(TG) and gas chromatograph-mass spectrometry (GC-MS) with various heating rates, reaction temperatures and mixing ratios. As the reaction temperatures and heating rates increase, the yield of liquid products decreases, whereas that of gaseous products increases. The co-pyrolysis reaction temperature of wood and polypropylene mixtures for the maximum yield of liquids was 500 ~ 600 ℃. The yields of carbon dioxide and carbon monoxide decrease as the reaction temperatures and heating rates increase.

PUD pilot에서 자동점도 측정을 이용한 교반효과에 관한 연구

polyurethane; prepolymer; dispersion; viscosity

Polyurethane dispersion (PUD) was prepared with polycarbonate diol (PCD), isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) in a 8 L pilot reactor. The end point of prepolymerization step was measured by the change in the torque of the stirring motor which is related to the viscosity of reaction mixtures. The changes in the viscosity of reaction mixtures, particle size distributionof PUD, water evaporation rate in film casting and thermal properties of cast film were investigated as varying the stirring rate in dispersion step. During the dispersion step, the viscosity of reaction mixture increased initially, and then decreased sometime later. The extent of viscosity increase and particle size of PUD decreased with the stirring rate. As the particle size became smaller, the evaporation rate decreased. But thermal properties of cast film such as thermal decomposition temperature and glass temperature were not affected by the particle size of PUD.

염화철과 염화마그네슘을 이용한 염색폐수의 2단 응집처리

dye wastewater; coagulation-flocculation; chemical precipitation

This study was conducted to remove the organic pollutants and color in artificial and industrial dye wastewater using coagulation-flocculation processes. Through unit experiments ferric/ferrous chloride and magnesium chloride were chosen as the coagulants because they had high efficiencies. A combined two-staged process was used for this study; in the first stage coagulation-flocculation process used ferric/ferrous chloride coagulants, and in the second stage, coagulation-flocculation process used magnesium chloride coagulant. Results of the treatment artificial dye wastewater in reactive black 5 showed that organic matters and colors were removed 60% and 95%, respectively. In the dispersed red 13, organic matters and colors were removed 8% and 88%, respectively. In the reactive orange 16, organic matters were removed 35%, 17%, and 16% by ferrous chloride, magnesium chloride, ferric chloride, respectively, and colors were removed 85%, 76%, and 12% by magnesium chloride, ferrous chloride, and ferric chloride, respectively. In order to remove the organic matters and colors simultaneously, selective combinations of coagulation-flocculation were needed. Comparison of the two-stage processes showed that ferric chloride-magnesium chloride coagulation-flocculation process was more effective than ferrous chloride-magnesium chloride process in removing both the organic matters and colors.

광경화형 지방족 에폭시 아크릴레이트의 합성과 물성 (I)

aliphatic epoxy acrylate; photocurable; 1,4-butanediol diglycidyl ether; acrylic acid; reactive monomer

Photocurable aliphatic epoxy acrylate was prepared from acrylic acid and 1,4-butanediol diglycidyl ether that was obtanied by reacting 1,4-butanediol with with epichlorohydrin. After the dilution with three kinds of reactive monomers (2-hydroxyethyl acrylate, tri(propylene glycol) diacrylate, trimethylolpropane triacrylate), the properties of photocurable aliphatic epoxy acrylate were investigated. Their viscosities decreased with the increased amount of reactive monomers, but increased when higher functionality of monomers were used. Glass transition temperature of UV-cured film, obtained from tan peak of DMA (dimethylamine), shifted to higher temperatures as the functionality of monomer was increased, and thermal stability exhibited similar behavior. Hardness, abrasion resistance, and tensile strength of UV-cured film also increased with increased functionality of monomer, but elongation was reduced with the higher monomer functionality. In an accelerated weathering test, UV-cured film showed that the value of yellow index increased with increased functionality of monomer.

Maleic Acid의 Pd/C 촉매상 저압 수소화 반응의 반응 기구에 관한 연구

maleic acid; catalytic hydrogenation; mass transfer; fumaric acid; reaction mechanism

Hydrogenation reactions of maleic acid over Pd/C at a lower pressure were performed in aqueous solution while varying the hydrogen pressure, reaction temperature, reactant concentration, catalyst loading, and agitation speed and the effects on the reaction rate and product distribution were examined. Intrinsic reaction characteristics were studied from the results of reaction performed at higher agitation speed than that of industrial reaction condition. Succinic acid, fumaric acid and malic acid were abtained from the reaction. Both rates of formation of succinic acid and fumaric acid increased with hydrogen pressure and catalyst amount while that of malic acid a showed different trend, from which a mechanism for hydrogenation of maleic acid was suggested.

EPDM/PP계 열가소성 가교체의 유변특성 및 물성에 미치는 조성의 영향

EPDM; PP; thermoplastic olefin; thermoplastic vulcanizate

Effects of ethylene-propylene diene ter-monomer (EPDM)/polypropylene (PP) composition, oil and carbon black contents on the rheological and mechanical properties of thermoplastic olefin (TPO) and thermoplastic vulcanizate (TPV) based on EPDM/PP were investigated. It was found that the flow behavior of TPO and TPV followed the power-law behavior showing a typical pseudoplastic characteristics. Higher shear viscosity was observed with increased EPDM content. The shear viscosity decreased with increasing oil content, but no considerable effect was found by the addition of carbon black. Tensile strength of TPO decreased linearly with increasing EPDM content, while that of TPV maintained until 65 wt% and then rapidly decreased with further increase of EPDM content. Tensile moduli of TPO and TPV could be well predicted by the Coran-Patel model. When the content of EPDM was increased to about 70 wt%, phase inversion was observed for TPO, but it was not found for TPV.

일루미늄 제거 및 이온교환한 Y 타입 제올라이트의 수분흡착 특성

zeolite; dealumination; ion-exchange; desiccant; desiccant cooling system

In order to use as a desiccant for a desiccant cooling system, modified Y-type zeolite was prepared by EDTA treatment and ion-exchange with alkali metal cations such as Mg⁺², Ca⁺², Li⁺and K⁺. The water adsorption isotherm of modified zeolite was compared with that of the optimum separation factor (R = 0.07 ~ 0.1). From the comparison of adsorption isotherms with the optimum separation factor, Y-type zeolites treated by 0.5 ~ 0.6 g of EDTA/g-zeoite and exchanged by Li⁺ showed the optimal adsorption behaviors. Then, theh optimal modified zeolite was mixed with water, polyurethane and N-methyl-2-pyrrolidone, which was then coated onto aluminum substrate. It was found that the optimal mixing ratio of modified zeolite, water, polyurethane and N-methyl-2-pyrrolidone were 6:4:2:1, respectively.

지방산 아마이드계 섬유용 유연제 합성과 물성에 대한 연구; Part I

amidoamines; imidazoline; particle sizes; foam stability; antistatic property

Amidoamines with amide group were synthesized by the reaction of fatty acid with polyamine. The mole ratio in preparing amidoamines was 1 : 1 and 2 : 1. The reaction temperature was set at three different temperatures: 150 ℃, 180 ℃ and 200 ℃. Quarternary amidoamines were synthesized by using acetic acid (Ac) and benzyl chloride (BC). Quarternary amidoamines were then emulsified by addition of emulsifier and Ac. The reaction time of synthesizing amidoamines was found to decrease with increasing the reaction temperature. However, imidazoline formed as the by-product with increased temperature. The color change of amidoamines was minimized by addition of SHPP. The particle sizes of quarternary amidoamines were smaller when Ac was used compared to the case of BC. Also, the emulsified quarternary amidoamines resulted in smaller particle sizes with better flexibility. Due to the increased hydrophobicity, the foam stability of diamide was poor compared to mono-amide. Polyester, which has negative charges, showed a better antistatic property than nylon.

지방산 아마이드계 섬유용 유연제 합성과 물성에 대한 연구: Part II

amidoamines; imidazolines; emulsifying stability; flexible property; antistatic property

Imidazolines were synthesized by reacting at 1 ~ 3 torr for 3hrs after preparing amidoamines through the reaction of amide at 150 ℃ using fatty acid and polyamines. The quarternization was carried out using amidoamines, imidazolines and quarternizing agent such as dimethyl sulfate (DMS), benzyl chloride (MBC) and sodium chloroacetate (SMCA). Emulsifying quarternaries were prepared in two types: emulsifier system and emulsifier free system. In the reaction systems using diethylenetriamine (DETA) and 1:1 reaction using 2-(2-Aminoethyl-amino)ethanol (AEEA), the amidoamines and imidazolines were prepared. However, in 2:1 reaction using AEEA, no imidazolines were produced. The stability of quarternary was better with pH treatment and with the smulsifying system than the emulsifier free system and alkali system. In the flexible property of amidoamines improved with added emulsifier. Imidazolines showed a better flexible property than amidoamines. In general, the emulsifying system created more foam than the emulsifier free system. As for the antistatic property, polyamines used with AEEA system were better than that with DETA. Polyester type specimen for textile treatment showed a good antistatic property.

Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst

Thermal & Catalytic Degradation; Spent FCC Catalyst; Waste HDPE; Liquid Product Distribution

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430 ℃ into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.

The Effects of Impeller Characteristics in the Hydrogenation of Aniline on Ru/C Catalyst

Impeller Characteristics; Hydrogenation of Aniline; Reaction Rate; Product Selectivity; Hydrogen Concentration

Effects of impeller characteristics have been studied in the hydrogenation of aniline on Ru/C catalyst. Dual impellers were employed and the experiments were performed at 300 rpm using a lab-scale reactor. Reaction with disk turbines (DT) resulted in the higher cyclohexylamine (CHA) selectivity and higher reaction rate compared to that with pitched blade turbines (PBT). When a combination of PBT and DT impellers was employed, high product selectivity and reaction rate were obtained and the selectivity was maintained constant. Changes in the product selectivity with the impeller geometry were explained in terms of the relative rates of the side reactions depending on the hydrogen concentration in the reaction mixture.

Ozone Kinetics and Diesel Decomposition by Ozonation in Groundwater

Ozone; Groundwater; Diesel; Hydroxyl Radical; Hydrogen Peroxide

The ozone kinetics (ozone auto-decomposition; effects of pH and solubility) and diesel/TCE/PCE decomposition (effects of hydroxyl radical scavenger, pH, and ozone/H2O2) by ozonation process were investigated in aqueous phase using deionized water, simulated groundwater, and actual groundwater. Reactions with deionized water and groundwater both showed the second-order reaction rates: the reaction rate was much higher in groundwater (half-life of 14.7 min) than in deionized water (half-life of 37.5 min). It was accelerated at high pH condition in both waters. The use of ozone showed high oxidation rates of TCE, PCE, and diesel. Hydroxyl radical scavengers acted as inhibitors for diesel decomposition, and high pH condition and addition of hydrogen peroxide could promote to degrade diesel in groundwater indicating ozone oxidation process could be effectively applied to treating diesel contaminated-groundwater.

Physico-chemical Processes Occurring Inside a Pyrolyzing Two-Dimensional Tobacco Particle

Tobacco Pyrolysis; Mathematical Model; Smoldering; Puffing

A two-dimensional, variable property, mathematical model of the transient pyrolysis of tobacco particle, in response to the smoldering (low heating rate) and puffing (fast heating rate) conditions in a burning cigarette, is presented. The model considers pyrolysis of tobacco obeying four-step Arrhenius kinetics, evaporation of water from tobacco following a mass-transfer and rate-determined process, and the formation of carbonaceous residue. From the physical point of view, the model describes convective, conductive and radiative heat transfer, and velocity and pressure variations interior to the porous tobacco particle (Darcy’s law). Furthermore, porosity, permeability and thermal conductivity vary with the composition of the reacting medium. Time and space evolution of the main variables, and reaction product distribution, are simulated by varying the tobacco heating rates.

Catalytic Degradation of Waste Polyolefinic Polymers using Spent FCC Catalyst with Various Experimental Variables

Catalytic Degradation; Spent FCC Catalyst; Catalyst Amount; Reaction Temperature; Deactivation of Catalyst; Plastic Type

Liquid-phase catalytic degradation of waste polyolefinic polymers (HDPE, LDPE, PP) over spent fluid catalytic cracking (FCC) catalyst was carried out at atmospheric pressure with a stirred semi-batch operation. The effect of experimental variables, such as catalyst amount, reaction temperature, plastic types and weight ratio of mixed plastic on the yield and accumulative amount distribution of liquid product for catalytic degradation was investigated. The initial rate of catalytic degradation of waste HDPE was linearly increased with catalyst amount (4-12 wt%), while that was exponentially increased with reaction temperature (350-430 ℃). Spent FCC catalyst in the liquid-phase catalytic degradation of polymer was not deactivated fast. The product distribution from catalytic degradation using spent FCC catalyst strongly depended on the plastic type. The catalytic degradation of mixed plastic (HDPE : LDPE : PP : PS=3 : 2 : 3 : 1) showed lower degradation temperature by about 20 ℃ than that of pure HDPE.

Phase Behaviors of Binary Protein Systems: Consideration of Structural Effects

pre-aggregation; binary protein system; interaction potentials; phase equilibria

A molecular-thermodynamic model to describe the salt-induced protein precipitation is developed based on the perturbation theory. We employed the modified perturbed hard-sphere-chain (PHSC) equation of state for copolymer mixtures to take into account the pre-aggregation effect among protein particles. Hypothetical pressure-composition diagrams are computed with various size differences and salt concentrations. The precipitation behaviors are also studied for various types of pre-aggregation effect for the given systems.

In Situ Detection of the Onset of Phase Separation and Gelation in Epoxy/Anhydride/Thermoplastic Blends

cure reaction; epoxy/thermoplastic; phase separation; rheological measurement; rheological behavior

The isothermal cure reactions of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer (poly(dimmer acid-co-alkyl polyamine)) or PEI were studied using differential scanning calorimetry (DSC). Rheological measurements have been made to investigate the viscosity and mechanical relaxation behavior of the blends. The reaction rate and the final cure conversion were decreased with increasing the amount of thermoplastics in the blends. Lower values of final cure conversions in the epoxy/thermoplastic blends indicate that thermoplastics hinder the cure reaction between the epoxy and the curing agent. Complete miscibility was observed in the uncured blends of epoxy/thermoplastics up to 120 ℃ but phase separations occurred in the early stages of the curing process at higher temperatures than 120 ℃. According to the rheological measurement results, a rise of G' and G'' at the onset of phase separation is seen. A rise of G' and G'' is not observed for neat epoxy system since no phase separation is seen during cure reaction. At the onset of phase separation the rheological behavior was influenced by the amount of thermoplastics in the epoxy/thermoplastic blends, and the onset of phase separation can be detected by rheological measurements.

Fatigue Crack Growth Behavior of NR and HNBR Based Vulcanizates with Potential Application to Track Pad for Heavy Weight Vehicles

track pad; NR; HNBR; ZSC; crack propagation rate

Generally, field performance of elastomeric track pad components has been poor, especially for the medium to heavy tonnage tracked vehicles, which are operated on the hilly cross-country course. The service life of these track pad, is affected not only by the terrain and environmental conditions but also by the speed, cornering, braking, weight of the vehicle, and the track tread design. In this research, modulus, tearing energy, and the rate of crack propagation of vulcanizates are evaluated by changing base materials to improve the service time of track pad. By increasing the contents of carbon black, modulus, tearing energy, and fatigue crack growth resistance of vulcanizates improved. Compared with the NR vulcanizate, the HNBR vulcanizate had a higher value of tearing energy. The rate of crack propagation of vulcanizates using smaller size carbon black was slower than that using larger size carbon black. When the HNBR was blended with the ZSC, the tearing energy of the vulcanizates was a little reduced because of the high modulus but the crack propagation rate was reduced significantly. In the relation between the crack propagation rate and the strain energy release rate, though up to 100% strain were applied to specimens, the slope on the log scale (β) varied between 1.72 and 2.3 with the kind of elastomer.

플라즈마 처리된 폴리이써설폰 막의 CO2/N2 혼합가스의 투과거동에 대한 연구

Polyethersulfone; Plasma Treatment; Selectivity; Permeation

The surface of polyethersulfone(PES) membrane treated by Ar, NH3 plasma, and the effects were observed before and after the treatment. The membrane treated by Ar plasma was increased the O/C ratio and measured the hydrophilic group, and the one by NH3 plasma was attached the amine group and the amino group. In addition, with the wettability of polyethersulfone membrane CO2 and the polar functional groups of surface interacted increasingly. Thus by comparable increase of the soluble selectivity CO2 to N2 both the permeability and the selectivity of CO2 was improved. The optimum condition for the CO2 permeation and actual separation factor of the plasma treated membrane was as follows; the measurement of Ar-10 W-2 min plasma treatment was 13.19×10(-10) cm(3)(STP)cm/cm(2) · s · cmHg and 20.12, and the measurement of NH3-50 W-2 min plasma treatment was 15.40×10(-10)cm(3)(STP)cm/cm(2) · s · cmHg and 20.06.

질산 인듐과 염화 주석으로부터 얻어진 인듐주석산화 분말의 합성에서 첨가제와 소성 조건의 영향

ITO; Homogeneous Precipitation; Urea; Surface Area

To synthesize ITO powder, indium nitrate and tin chloride were first dissolved in ethanol or distilled water, and then 0.5 M NH4OH as a precipitation agent and urea as an additive were added to the solution. In addition, the effect of sintering conditions on particle size and specific surface area of product powder was observed. As a result, the particle size decreased with decreasing the concentration of indium nitrate. We also found that the non-agglomerated small particles with narrow size distribution could be observed by longer gelation time due to the addition of urea. Finally, it showed that the specific surface area has a maximum value(about 98 m(2)/g) at 350 ℃ and 1 hr condition, and the particle size has a minimum value (about 47 nm) at following conditions(350 ℃ 1 hr and 550 ℃ 30 min).

플라즈마 처리된 폴리설폰 막의 CO2/N2 혼합가스의 투과분리에 대한 연구

Polysulfone; Plasma Treatment; Selectivity; Permeation

The surface of polysulfone(PSf) membrane modified by Ar, NH3 plasma treatment is measured before and after the treatment. The membrane modified by Ar plasma treatment is increased the O/C ratio and the hydrophilic group, by NH3 plasma treatment is increased the amine group and the amino group. The CO2 permeation and ideal separation factor of the treated membrane measured good condition. The measurance of Ar-10 W-6 min plasma treatment is 8.6744×10(-10) cm(3)(STP)cm/cm(2)ㆍsㆍcmHg and 14.401, it of NH3-50 W-8 min plasma treatment is 7.5922×10 (-10)cm(3)(STP)cm/cm(2)ㆍsㆍcmHg and 17.644. Having the wettability of polysulfone membrane, the polar functional groups of its surface interacted with CO2 increasingly. Because of the soluble selectivity of membrane increased of CO2 than N2, polysulfone membrane improved both the permeability and the selectivity of CO2.

Exergy Analysis of Cryogenic Air Separation Process for Generating Nitrogen

exergy analysis; air separation; nitrogen generation

A cryogenic air separation process that generates nitrogen has different process configurations depending on the utilization of either a cold heat supply method or a distillation method. Each method presents different initial investment costs, operating costs and energy efficiencies. Therefore, an accurate estimation of the energy efficiency as well as the cost is an important factor in selecting an appropriate process and in designing the most efficient equipment. Accordingly, the current study formulated criteria that can be applied to select the most efficient process. Processes using liquid nitrogen and an expansion turbine representing different cold heat supply methods were analyzed and evaluated to compare the exergy efficiency. In addition, the exergy efficiency of structure packing and sieve tray distillation method was also compared based on the experimental results.

Surface Modification with Waterborne Fluorinated Non-ionic Polyurethane Dispersion

waterborne fluorinated polyurethane dispersion; waterborne polyurethane dispersion; surface energy; glass transition temperature; compatibility

Waterborne fluorinated non-ionic polyurethane dispersions (FNPUDs) were synthesized from tris(6-isocyanatohexyl) isocyanurate (TIHI), N-ethyl-N-2-hydroxylethyl-perfluorooctanesulfonamide (HFA), poly(oxyethylene glycol) (PEG) and 1,4-butanediol (BD). Waterborne polyurethane dispersion (PUD) was synthesized from isophorone diisocyanate (IPDI), poly(oxytetramethylene glycol) (PTMG), dimethylolpropionic acid (DMPA) and ethylenediamine (EDA). Fluorine PUD mixtures (FPMs) were prepared by blending the FNPUDs into the PUD. The particle size of the FNPUDs was measured by using dynamic light scattering (DLS), and the surface energy estimation and thermal property of the FPMs were studied by using a contact angle analyzer and differential scanning calorimetry (DSC). The particle size and glass transition temperature (Tg) of the FNPUDs tended to increase as the fluorine content in the FNPUD increased. When the fluorine content was 0.087 wt%, based on the total solid content, the surface energies of the FPMs exhibited the lowest values. In the same fluorine content in the FPMs, the surface energies of FPMs containing a higher fluorine content in the FNPUD exhibited a lower surface energy than those containing a lower fluorine content in the FNPUD. The thermal properties of the FPMs were found to be similar to the pure PUD. Accordingly, these results indicate that the phase separation and thermal behavior of the FNPUDs did not appear due to the compatibility of the polyether type PUD and the FNPUDs.

Preparation and Adhesive Properties of Azoester-modified SBS Triblock Copolymers

Isopropyl azodicarboxylate (IAD); SBS triblock copolymers; adhesive strength; interfacial bonding

Styrene-butadiene-styrene triblock copolymer (SBS) has been modified by reaction with isopropyl azodicarboxylate (IAD). Tg of the butadiene block, tensile strength and stiffness of the block copolymer increase with modification level, which is attributed to increased polar interactions between the chains. Peel strength of Al laminiate and Nylon-6 laminate bonded with modified SBS was investigated. The incorporation of adequate amount of the IAD onto the block copolymer improves its adhesive strength over metal and nylon-6 substrate substantially. In the case of nylon-6/modified SBS joints, their bond strength increased with increasing contact time at a particular temperature range. It is suggested that in the temperature range of 160 ~ 200 ℃, there is a reaction between the carboxyl group of modified SBS and the amino group of nylon-6 to form interfacial chemical bonds, which controls the adhesion behavior of SEB-g-IAD/nylon-6 joints.

The Computational Simulation of Skin-Permeation of Vitamins C and E

skin permeation; vitamin C; vitamin E; bilayer-bioconversion model

An advanced two-dimensional bilayer skin bioconversion model is developed to assay the skin-permeation of vitamins C and E. The numerical method of line (NMOL) is exploited to solve a set of governing equations based on species mass balance. The penetration profiles of vitamins C and E in the stratum corneum decrease quickly along the depth of the stratum corneum. But the penetration profile of vitamin C is more uniform than that of vitamin E along the depth of the viable skin. This result shows that a large amount of vitamin E is bio-converted by the enzyme in the viable skin. The first order kinetics of vitamins C and E bioconversion in the viable skin is assumed as the exponential decay law due to skin aging. The developed model is useful when evaluating skin penetration of vitamins C and E, not only to predict the penetration profiles but also to examine how much enzyme in the viable skin affects skin-penetration of vitamins C and E.

실시간 In-situ IR을 사용한 벌크상 Poly(oxytetramethylene) Glycol과 Isophorone Diisocyanate의 반응속도론 연구

PTMG; IPDI; kinetics; polyurethane; real-time in-situ IR spectroscopy

Using quantitative real-time In-situ infrared (In-situ IR) spectroscopy, kinetic study of a reaction between isophoron diisocyanate (IPDI) and poly(oxytetramethylene) glycol (PTMG) was carried out. The reaction rate was obtained from monitoring the change of NCO (2265 cm^-1) and C=O (1725 cm^-1) stretching band in series IR spectra. The reaction was in accordance with the first-order reaction for each concentration of hydroxyl groupsnd isocyanate group, respectively, however, the overall reaction conformed to the second-order law. In the bulk polymerization between PTMG and IPDI, with ratio of [NCO]/[OH] equal to 1.0 at various temperatures, the activation parameters obtained from the evaluation of kinetic data were ΔH^#=58.18 kJ/mol, ΔS^#= -95.98 J/mol·K and E_a=61.07 kJ/mol.

Poly(hexamethylene carbonate) glycol/Poly(oxytetramethylene) glycol 혼합 폴리올을 도입한 수분산성 폴리우레탄의 제조와 물성

polyurethane dispersion; phase separation; ionic content; mixed polyol

Using poly[hexamethylene carbonate] glycol (PHMCG) and poly[oxytetramethylene] glycol (PTMG) as the carbonate type and ether type polyols, respectively, and by adding isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA), polyurethane dispersions (PUD) were prepared. The effect of type and composition of polyols on the particle size of PUD and on the mechanical and thermal properties of PUD cast films were investigated. As the PTMG contents in the mixed polyols increased the particle size asymptotically increased, while tensile strength showed a slight decrease followed by a slight increase. This was due to the incompatibility of two polyols, which was confirmed by DSC analysis.

아민 기가 화학 결합된 유기 kenyaite의 제조와 나노복합재로의 응용

kenyaite; silylation; intercalation; layered silicate; nanocomposite

Functional organo-kenyaite that chemically bonded interlayer surface with amine groups was prepared by silylation of γ-aminopropyltriethoxysilane (APS) with interlayer Si-OH groups in the presence of gallery expander, dodecylamine (DDA), in ethanol. The intercalation and silylation were driven by entropy difference between the interlayer gallery and the outside, and the difference was due to the vaporization of ethanol from the slurry, composed of APS, DDA, H-kenyaite and ethanol. XRD analysis of dried organo-kenyaite revealed well-ordered larged-spacing of 4.14 ~ 5.12 nm. It was confirmed that the gallery height increased up to 2.3 ~ 3.3 nm. Solid-state ²⁹Si MAS NMR peak showed that Q⁴/Q³ of organo-kenyaite increased substantially compared to Q⁴/Q³ of H-kenyaite, confirming successful silylation of APS with Si-OH groups in the interlayer surface. This process was performed at atmospheric condition without excess use of expensive reagent of effluent of waste liquid. Polymer-clay nanocomposite was prepared by mixing epoxy resin and organo-kenyaite. The Properties of the nanocomposite were measured by TEM and SAXS. The distance of the interlayer was expanded up to 5 ~ 6 nm. Nanocomposite was well exfoliated and dispersed by the extension of interlayer that was due to the intercalation of epoxy resin. The results offered a promising route to the preparation of organolayered kenyaite with various functional groups bonded chemically in the interlayer surface.

W/O EMULSION을 이용한 구형 실리카 입자의 제조와 크기 제어

silica particles; emulsion; particle size; size distribution; sol-gel reaction

Spherical silica particles were prepared using W/O emulsion through the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS). In the preparation of particles, the effects of hydroxypropyl cellulose (HPC), molar ratio of water to TEOS (Rw), the amount of emulsifier (Span 80 or Span 80/Tween 20 mixed surfactants) were investigated. The morphology and size distribution of silica particles were greatly influenced by the stability of emulsion. In general, the size of silica particles decreased and the size distribution of particles became narrow as the amount of HPC, Rw and the amount of emulsifier increased.

In-situ 담지된 메탈로센 촉매들의 폴리올레핀 중합 특성에 미치는 조촉매 종류의 영향

in-situ supporting; bimetallic [(CH2)5(C5H4)2][(C9H7)ZrCl2]2 catalyst; ethylene polymerization; propylene polymerization; alkyl aluminum

An in-situ supporting method was applied to a new metallocene catalyst with a bulky structure, [(CH2)5(C5H4)2][(C9H7)ZrCl2]2, and other commercial metallocene catalysts; the polymerization characteristics of the supported catalysts were studied. Polyethylene obtained from the in-situ supported [(CH2)5(C5H4)2][(C9H7)ZrCl2]2/TMA catalyst showed a higher yield, a better morphology, a lower average molecular weight, and a broader molecular weight distribution than the catalyst supported by a traditional method. In-situ supported catalysts also showed that catalytic activities and polymer properties depended on the type of the cocatalyst used. When an alkyl aluminum was used as a cocatalyst, a lower activity was observed than the case of modified methylaluminoxan (MMAO), but it showed the characteristics similar to a heterogeneous catalyst. Trimethyl aluminum (TMA) showed the highest activity in polymerization among other alkyl aluminums, but excess addition of TMA resulted in a lower average molecular weight and activity by inducing deactivation of metallocenes of chain transfer. An in-situ supported rac-Et(Ind)2ZrCl2 catalyst produced the polypropylene with a higher melting temperature and a lower average molecular weight than a homogeneous system.

Melt-blown 방식에 의한 Polypropylene(PP) 카트리지 필터 제조시 공정인자가 필터소재의 여과특성에 미치는 영향

melt-blown; polypropylene cartridge filler media; melt-blown processing parameters; filtration characteristics

A polypropylene(PP) cartridge pre-filter media for water purification was obtained from a melt-blown extrusion method. The effect of melt-blown processing conditions on the fiber structure and the packing density of polypropylene cartridge filter element were investigated. And the filtration characteristics of them made in the various conditions of the melt-blown processing parameters, such as the air velocity and polymer throughout rate, were studied. The fiber diameters of what made with the melt-blown extrusion method which was equipped the single-nozzle decreased as the air velocity increased, however increased as the polymer throughout rate increased. The experimental results show the possibility of controling the mean pore size and filtration characteristics of polypropylene (PP) cartridge filter element for water purification with controlling of the processing conditions using the melt-blown extrusion method.

지방족 폴리에스테르의 생분해성에 미치는 구조 및 형태학적 영향

aliphatic polyesters; biodegradation; highly-ordered structure; enzymatic degradation; hydrolytic degradation

Aliphatic polyesters as biodegradable polymeric materials, which were prepared from various constituent monomers, are considered as the most probable counterproposal to solve the environmental pollution problem by disposal plastics. Therefore, many researchers have been carried out in terms of synthesis for new biodegradable materials by employing molecular design concept or modification of well-known aliphatic polyesters such as PHB, PCL, PLLA and PBS to improve biodegradablility, mechanical properties, processability and price competitiveness. It is well known that biodegradability of aliphatic polyesters is strongly dependent on primary structure determined by synthesis process. but in an attempt to study the effects of primary structure on biodegradation, incorrect conclusions might be drawn on the most dominant factor affecting biodegradability regardless of morphological factors and highly-ordered structure. In everyday life, most biodegradable polyesters are used in solid state such as a bulk container, films or fiber. Therefore, the biodegradability of polymers in solid state are significantly influenced by morphological factors and highly-ordered structure such as the crystal shape and size, crystallinity and molecular orientation as well as the chemical structure such as the degree of polymerization, the presence of functional groups, the hydrophilicity/hydrophobicity balance and crosslinking structure. In this paper, the morphological factor and highly ordered structure was evaluated by means of TEM and wide-/small-angle X-ray scattering, and the relationship between these factors and the biodegradability of aliphatic polyesters was examined in detail.

천연고무의 마찰특성에 미치는 염소화의 영향

natural rubber; chlorination; friction; hardness

Using a new friction tester, the frictional property of chlorinated-natural rubber sheet was investigated as a function of the chlorination time. The changes in molecular structure, morphology, and hardness on the surface of the rubber sheet were also investigated with the chlorination time. It was confirmed that the molecular structure on the surface of natural rubber sheet has changed due to the chlorination reaction, and with a longer chlorination treatments a cyclization reaction was observed. The frictional coefficient decreased significantly with increasing the chlorination time, and the decrease rate was the highest at the initial stage of the chlorination reaction. Such rapid drop in the frictional coefficient--upon chlorination--can explained by two main parameters: surface roughness and hardness. The increase in the hardness caused a reduction in both the contact area and deformation of rubber, thereby decreasing the adhesive and hysteresis frictions. The increase in the surface roughness reduced the contact area, which in turn decreased the adhesive friction.

연속 반응기에서 분산제 없이 제조된 TiO2 나노 입자와 회분식 및 반회분식 반응기에서 분산제를 사용하여 제조된 입자와의 비교

TiO2; batch; semi-batch; continuous

A new preparation method to produce TiO2 nanoparticles is introduced. This method consisted of a small reactor for mixing starting materials and an aging tube to control the size and distribution of TiO2 fine particles. The particles prepared by a continuous reaction method without dispersant had a smaller mean particle size and smaller standard deviation than that obtained from the batch or semi-batch process with dispersant. In this work, it was also found that the size and stantdard deviation of TiO2 particles decreased by using an intermittent flow type for the aging tube. With the optimal process, TiO2 particles obtained had a mean diameter as small as 50 nm.

탱크형 반응기를 이용한 파라핀 왁스 산화반응에서의 공정변수 영향

paraffin wax; oxidation; scale-up; saponification value; gas-liquid-solid mixing

In order to the optimize the reaction condition for oxidation of paraffin wax in a stirred tank reactor, the effects of process variables on the degree of oxidation were examined. Shape of the gas diffuser, particle size of the catalyst, type of the impeller, flow rate of air, and stirrer speed significantly influenced the mass transfer among gas-liquid-solid phases. These were important variables that enhanced the acid and saponification values of the oxidized paraffin wax. Amount of catalyst, reaction temperature and reaction time were also important variables, but too high values of these caused a secondary oxidation that decreased the oxidation degree and discoloration of the product. In a scale-up experiment with a 100 L-volume reactor, a good quality product with high degree of oxidation (AV 145, SV 250) was obtained, confirming the possibility of a successful scale-up.

Cure Reactions of Epoxy/Anhydride/(Polyamide Copolymer) Blends

cure kinetics; epoxy; polyamide copolymer; diffusion control

The cure kinetics of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer, poly(dimmer acid-co-alkyl polyamine), were studied using differential scanning calorimetry (DSC) under isothermal condition. On increasing the amount of polyamide copolymer in the blends, the reaction rate was increased and the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/(polyamide copolymer) blends indicate that polyamide hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending polyamide copolymer with epoxy resin, and the value was approximately 1.3, whereas the reaction order, n, for the general nth order of reaction was increased by increasing the amount of polyamide copolymer in the blends, and the value increased from 1.6 to 4.0. A diffusion-controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/(polyamide copolymer) blends. Complete miscibility was observed in the uncured blends of epoxy/(polyamide copolymer) up to 120 ℃, but phase separations occurred in the early stages of the curing process at higher temperatures than 120 ℃. During the curing process, the cure reaction involving the functional group in polyamide copolymer was detected on a DSC thermogram.

Poly(ethylene terephthalate)(PET) Nanocomposites Filled with Fumed Silicas by Melt Compounding

poly(ethylene terephthalate); nanocomposite; fumed silica; melt compounding; rheology

PET nanocomposites filled with fumed silicas were prepared via direct melt compounding method at various mixing conditions such as filler type and filler content. Some fumed silicas were pre-treated to improve the wettability and dispersibility, and principal characterizations were performed to investigate the effects of nano fumed silicas on polymer matrix. Hydrophobic fumed silica (M-FS), which has the similar contact angles of water with neat PET, acted as the best reinforcement for the thermal stability and mechanical properties of PET nanocomposite, and FE-SEM images also showed that M-FS was uniformly dispersed into matrix and had good wettability. But, some filler (O-FS) had low dispersibility and caused the deterioration of mechanical properties. Besides, the results of DSC revealed the nucleation effect of all fillers in polymer matrix, and PET nanocomposite filled with hydrophilic fumed silica (FS) showed markedly the characteristic dynamic rheological properties such as shear thinning behavior at very low frequencies and the decrease of viscosity.

Zirconocene-catalyzed Copolymerizations of Ethylene with 5-Methyl-1,4-hexadiene as Non-conjugated Diene

zirconocene; copolymerization; functional poly(α-olefin); non-conjugated diene

The mixtures of non-conjugated dienes, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene (MHD), were successfully synthesized by the reaction of isoprene with ethylene using Fe(III)-based catalyst in toluene. The conversion was over 96 mol% on the basis of the initial amount of isoprene used. The production yield for MHD was nearly 50 mol%, the other was polyisoprene. The mixtures were successfully copolymerized with ethylene by using zirconium-based metallocenes. The products were characterized by the combinations of gas chromatography, high temperature gel permeation chromatography, 1H NMR, 13C NMR, high temperature 1H NMR, UV/Visible spectroscopy, and differential scanning calorimetry. It was found that 5-methyl-1,4-hexadiene was active enough to be incorporated into the copolymer chain but the corresponding isomeric material, 4-methyl-1,4-hexadiene, was inactive in metallocene-catalyzed copolymerizations. Specifically, in the zirconocene-catalyzed copolymerizations of ethylene with MHD, ansa-structure catalysts seem to be more efficient than non-bridged type zirconocene. The degree of incorporation of MHD in the resulting copolymers was able to be controlled by the amount of non-conjugated dienes used initially.

고체 촉매에서 CF3COOH의 직접 요오드화반응에 의한 CF3I의 합성

Impregnated Catalysts; Reaction Condition; CF3I Synthesis; Direct Iodination of CF3COOH

Synthesis of CF3I by direct iodination of CF3COOH with iodine was carried out in a flow reactor over various salt-impregnated catalysts. In this experiment, the effects of support types, salt types and salt contents for the manufactured catalysts and also those of reaction conditions such as reaction temperature, contact time and feeding mole ratio of reactant were tested. A longer contact time led to the higher yield of CF3I. The optimized reaction conditions were above 1 of I2/CF3COOH mole ratio and about 400℃ of reaction temperature. Active-carbon as a support showed better performance than alumina. For the salt impregnated on support, the best results of both salt content and salt type were 7.5 weight percentage and CuI type, respectively.

Mini-Pilot Scale Production of Homopolymer and Block Copolymer by Anionic Polymerization

anionic polymerization; scale-up; homopolymer; block copolymer; controlled molecular weight; low polydispersity index

In order to obtain a large amount of polymer samples with a well-controlled molecular weight and polydispersity index, a bench scale reactor system for anionic polymerization was built instead of the traditional break-seal method. Homopolymers were successfully prepared from non-polar monomers in amounts of 40 ~ 350 g with well-defined structures. The major process variables were found to be the type of initiator, monomer concentration. and the volume of the reaction mixture. When a higher monomer concentration or larger reaction mixture volume was used, the removal of reaction heat became critical. In the case of a polar monomer, close control of the anionic polymerization was required to obtain a lower PDI. In the preparation of a diene-acryl block copolymer, it was found that the thorough removal of any impurities from the second monomer was critical for suppressing the generation of a homopolymer.

Synthesis of Titanium Dioxide Nanoparticles by Reversible Reaction in Semibatch-Batch Mixed Method

Titanium Dioxide; Reversible Reaction; Nanoparticles; Semibatch-Batch

A new preparation method of particles is introduced, which consists of a semibatch-batch two-stage reaction to decrease the size of TiO2 particles. Using a semibatch process as the first stage, the particle size grows to a certain level (138 nm). However, when using a batch process as the second stage, the particle size decreases about 30 nm. The particles prepared using the two-stage (semibatch-batch) method have a smaller mean particle size and smaller standard deviation than those obtained from the single stage process. It was found that as the concentration of TEOT in the second stage increased, the difference in the particle size between the first and second stages also increased. In this paper, the concentration equilibrium constant (K(eq)) was calculated to predict the effect: of the two-stage mixed system on decreasing the particle size. As a result, the higher the concentration of TEOT in tile second stage, the smaller the K(eq) value. A decrease in K(eq) indicates the occurrence of a reversible reaction. In other words, an increase in the reverse reaction rate constant (k(H,r)) results in a decrease in the particle size. The experimental results (particle size) using the above reaction method could be anticipated with the theoretical approach and produced the smallest particle size (similar to 30 nm in diameter).

에스테르 교환반응을 이용한 Cyclohexanedimethanol(CHDM) 함유 지방족 폴리에스테르 공중합체의 제조와 물성

poly(butylene succinate); poly(cyclohexane dimethylene adipate); PBS-PCDA copolymer; melt blending; transesterification

Poly(cyclohexane dimethylene adipate)(PCDA) containing rigid ring structures was synthesized with adipic acid and cyclohexanedimethanol(CHDM). PCDA was melted and blended with the biodegradable aliphatic polyester and poly(butylene succinate)(PBS) to obtain PBS-PCDA copolymer. The structures of PCDA and PBS-PCDA copolymers were confirmed by FT-IR and (1)H-NMR. The thermal and mechanical properties of the copolymers were investigated by DSC, TGA and UTM. When PCDA was introduced into the PBS chain, there was a decrease in the melting temperature and the crystallization rate, but it increased the toughness and the thermal stability.

펜톤반응에서 pH의 변화에 따른 산화 및 환원반응 메커니즘

carbon tetrachloride; 1-hexanol; superoxide radical; hydroperoxide anion; fenton's reaction

The mechanisms of oxidation and reduction in Fenton's reagent were investigated using 1-hexanol and carbon tetrachloride (CT). Degradation of these compounds was investigated using different concentrations of hydrogen peroxide (2.94 mM ~ 1470 mM) at 1 mM concentration of ferric sulfate by varying pH from 3 to 12. The results showed that as pH was increased from 3 to 5, 7, 9, and 12, the degradation of 1-hexanol decreased significantly. Within 30 min (with 1470 mM of H2O2) of reaction time, decomposition of 1-hexanol was 99.9% at pH 3 ; however, only 5% was observed at pH 12. Carbon tetrachloride degradation showed different result; with 1470 mM of H2O2, 95% of initial CT concentration was decomposed at pH 3, but only 70% decomposed at pH 5. When pH was raised to 12, CT degradation reached up to 95% of the initial concentration. Furthermore, competition reactions were conducted at pH 3 and pH 9 to verify the formation of hydroxyl radical and reductants in Fenton's reagent. It was concluded that hydroxyl radical was the primary oxidant for the degradation of 1-hexanol, whereas in the degradation of CT, not the hydroxyl radical, but the reductants, superoxide radical and hydroperoxide anion were involved. This study indicates that Fenton reaction is a co-existing process of oxidative-reductive reaction.

Fe(III)-NTA로 촉매화된 유사펜톤반응을 이용한 1-헥산올과 사염화탄소의 분해

modified Fenton's reaction; nitrilotriacetic acid; hydroxyl radical; hydroperoxide anion; superoxide radicals

The purpose of this work is to evaluate the degradation rate of contaminants in modified Fenton's reagent using chelating agents (NTA, EDTA, citrate and oxalate) and to investigate coexisting oxidative-reductive mechanism under various pH and H2O2 concentrations. The modified Fenton's reaction using iron(III)-NTA showed maximum degradation of probe compounds: 1-hexanol and carbon tetrachloride (CT). In the modified Fenton's reaction, degradation of probes was higher at high concentration of H2O2. As the pH was increased from 3 to 9, the degradation rate of probes increased. However, the degradation of probes decreased significantly at pH 12. Normal Fenton's reaction was also conducted in parallel with the modified Fenton's reaction. The degradation of 1-hexanol was effectively processed at pH of 2 ~ 4. As pH was increased, the degradation of CT also increased. To confirm that the modified Fenton's reagent provided not only hydroxyl radicals but also reductants, the oxidation and reduction mechanisms were further studied by scavenging analyses using isopropanol as the hydroxyl radical scavenger and chloroform as the reductant scavenger. These results indicated that hydroxyl radical was the primary oxidant for 1-hexanol decomposition, whereas the degradation of CT was linked to the reductants, superoxide radicals (OO(-)·) and hydroperoxide anions (OOH(-)).

중금속 오염 토양 복원에 사용되는 Chelating agent의 회수 및 재사용에 대한 연구

chelating agent recovery; heavy metal; ligand exchange

The effectiveness of reapplying a recycled organic acid as the chelating agent following the treatment of contaminated soil was investigated. Following properties of the recycled metal-ligand complex were found under various pH regimes: 1) In citric acid, a small amount of copper was removed. The removal amount of lead increased until the solution's pH reached 11.5, and then it decreased as lead hydroxide formed. The precipitation of zinc increased at a constant rate as pH increased. 2) In oxalic acid, copper was removed completely as Cu(OH)2 at pH greater than 11.5. Lead and zinc precipitated readily due to the low solubility of the complexes even before the alkali solution was injected to the metal solution. The recovery and reuse of the organic acid in copper-contaminated soil was also investigated. As the frequency of reuse increased and as pH decreased, the removal efficiency of copper decreased, indicating that the amount of free ion of organic acid decreased in the recycled solution.

고무 혼합공정 중 동력곡선의 이론적 해석과 모사

rubber mixing; simulation; power torque curve; carbon black; incorporation; dispersion

A new theoretical approach was proposed for predicting power consumption during rubber mixing. The main assumptions in the theoretical approach include; 1) The mixing of carbon black into rubber matrix is divided into two stages: incorporation, in which agglomerated carbon blacks incorporate into softened rubber and dispersion, in which the incorporated carbon blacks in still agglomerated state further disperse into rubber matrix to become aggregate state, and the mixing rate is the first-order reaction, where the rate is proportional to the remaining carbon black concentration in each step, 2) The mixing torque is originated from viscosity of rubber compound and break-down of carbon black pellets, and it decreases exponentially with mixing time, 3) The viscosity change due to the rise in temperature during mixing follows the Arrhenius law. The power consumption curve was simulated by solving a series of theoritical equations suggested in this work. A fairly good agreement was found between the theoritical and actual power curves. Based on the simulation, the rate parameters for incorporation and dispersion of carbon blacks, viscosity reduction during mixing, time-dependent volume fraction, and power torque, which is very important in rubber mixing process could be obtained.

무연탄의 비연료 활용 : 활성탄의 제조와 흡착 특성 연구

anthracite activation; chmical pretreatment; alkali treatment; adsorption

Purpose of this study was to develope the activated carbons from domestic anthracite. The low ash coals were separated by a dense media technique, before the activation. The activated carbons were produced using either steam or CO2 for crushed and granulated coals. Chemical pre-treatment with alkali hydroxides (Na, K) was to increase the reactivity of anthracite during the activation. Liquid and gas phase adsorption tests were performed with organic compounds and heavy metals. Activated carbons having the surface areas of 650 m(2)/g and 920 m(2)/g were produced from crushed and granulate coals, respectively. The chemical pre-treatment of the crushed coals increased the surface area from 650 m(2)/g to 840 m(2)/g as well as increasing the pore size and burn-offs. It was found that the activated carbons produced from the crushed coals with the chemical pre-treatment and CO2 activation had a well-developed microporosity characteristic. The activated carbons that formed by steam activation of the graunles, however, had a wide-range of porosity. The crushed and franulated activated carbons are particularly suitable for gas phase and liquid phase adsorptions, respectively.

알코올 용액 중에서 TEOT의 가수분해에 의한 단분산 TiO2 미립자의 생성에 관한 속도론적 연구

TiO2; monodispersed; HPC; hydrolysis

To understand chemical and physical properties of fine titania particles, and to control diameter of the resulting fine particles, the hydrolysis of Ti(OC2H5)4 was carried out. In obtaining fine TiO2 particles fron Ti(OC2H5)4 consisted of two reaction steps: hydrolysis and polycondensation. The overall reaction was a second order with respect to the Ti(OC2H5)4 concentration and a fourth order with the H2O concentration. Mono-dispersed fine titania particles were produced when the mole ratio of H2O and Ti(OC2H5)4 was 2. During the reaction, aggregation was prevented by adding HPC, which is an dispersing agent. The result showed that shperical TiO2 particles with a narrow particle size distribution were obtained. From the XRD data it was concluded that the titania prepared by gydrolysis reaction was amorphous, and rutile TiO2, which was obtained by calcination at 800 ℃ for 2 h, had tetragonal structures. Using DT-TGA data analysis an approximate value of X of TiO2XH2O was obtained.

균일 침전법에 의한 ITO powder 합성

ITO; homogeneous precipitation; urea; HMTA

To synthesize ITO colloidal solution solute(dissloute) indium and tin in the ethanol, distilled water, iso-propanol, and butanol solvate were added to the solution with precipitation agent 1 M NH4OH, urea and HMTA. Observed particle size and crystal phase of ITO in different reaction condition. From the test result, if reaction temperature is higher, particle size becomes smaller. Furthermore unstable particles were made at higher temperature than 60 ℃. By analyzing surface area of ITO with different solution, we found that particle size was the biggest in the H2O solution and the smallest in butanol solution. However, the yield of ITO powder were changed by solution because of its different solubility. We also found that size of particles could be influenced by the longer gelation time due to the addition of urea and HMTA.

원자이동 라디칼중합을 이용한 아령모양 고차분지형 양친매성 블록공중합체의 합성

Amphiphilic block copolymer; Hyperbranched; ATRP; Chloromethylstyrene; Micelle

Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol) (PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by (1)H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for (1) H-NMR spectroscopic analysis.

Polystyrene/SBR 블렌드 발포체의 물성과 형태학적 변화에 대한 연구

Foam; Polystyrene; SBR; Kicker; Single Screw extruder

In this study, blends of polystyrene(PS) and Styrene-Butadiene-Rubber(SBR) were prepared by mixing in the kneader, and then the foams of blends were prepared by extruding with a foaming agent in a single screw exturder. We investigated the physical properties and morphological behaviors of blended foams by UTM, SEM and Densitmeter. The number of cells in the foamed PS/SBR blends matrix increased as the processing temperature decreased. Also, the structure of cell changed from closed cell structure to open cell structure as SBR fraction increased. In PS/SBR blends, the impact strength was improved by adding SBR, however, the flexural strength was decreased except for the 5 wt% SBR.

N-치환 측쇄를 갖는 폴리에테르 폴리우레탄 특성에 대한 측쇄 농도의 효과

Polyether polyurethane; Solid polymer eletrolytes; N-substituted polyurethane; Ionic conductivity; Thermal property

In order to study the effect of short polyether side chain contents on the properties of solid polymer electrolytes (SPE), which were based on a N-substituted PEOPU a series of N-substituted poly(ethylene oxide) polyurethane (N-sub PEOPU) with methyl of oligo (ethylene oxide) having different oligo (ethylene oxide) contents of substituents (0%, 35%, 65%, and 95%) were synthesized. Structure of the synthesized, N-sub PEOPU, was identified using fourier transform infrared spectrometer (FT-IR) and (1)H nuclear magnetic resonance spectroscopy ((1)H-NMR). Thermal properties were measured by a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). Ion-conductivity was measured as a function of salt concentration using an AC impedance analyzer. The glass transition temperature (T(g)) was gradually decreased to low temperature by increasing the contents of short polyether side chain concentration in N-sub PEOPU. The results of TGA showed that the thermal decomposition of N-sub PEOPU occurred at a higher temperature than PEOPU, and N-oligo(ethylene oxide) PEOPU, Me()_(EO)7 95, showed a lower thermal stability than that of N-methyl PEOPU. The highest conductivity of 5.9×10(-5) at 30 ℃ and 4.4×10(-3) at 70 ℃ was observed for Me35_(EO)7 65.

Fatigue Crack Growth Behavior of NR/EPDM Blend

Fatigue crack growth (FCG) behavior of natural rubber/ethylene-propylene-diene rubber (NR/EPDM) blend vulcanizates under dynamic tearing condition was investigated by using a fracture mechanics approach. It appeared that variation of crack growth rate with blend compositions was dependent on the level of imposed tearing energy G. At low tearing energy region, the FCG rates of the blend were lower as the EPDM content was increased, while at high tearing energy region, the trend was reversed. Over the measured range of tearing energy G, all blend compositions showed the lower crack growth rates compared to the average of properties of component elastomers. When the blends were thermally aged, the fatigue resistance of the blends was deteriorated in proportion to the concentration of EPDM phase. Fatigue crack growth behavior of the blends was supposed to be associated with the inhomogeneities of the crosslink structure of the blends arising from cure incompatibility of the EPDM and NR when they are sulphur cured.

Structural Changes of Biodegradable Poly(tetramethylene succinate) on Hydrolysis

Quenched and slow cooled as well as isothermally crystallized poly(tetramethylene succinate) (PTMS) films at two different temperatures were prepared. In the process of hydrolysis of the four specimens, structural changes such as the crystallinity, crystal size distribution, lattice parameter, lamellar thickness, long period and surface morphology were investigated by using wide and small angle X-ray scattering (WAXS and SAXS), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The hydrolytic degradation of quenched film was faster than that of slow cooled and isothermally crystallized films. The film crystallized at 100℃ exhibited extensive micro voids and thus showed faster degradation than that crystallized at 75℃, demonstrating surface morphology is another important factor to govern degradation rate. The crystallinity of the specimen increased by 5~10% and long period decreased after hydrolysis for 20 days. At the initial stage of degradation, the lamellar thickness of quenched film rather increased, while that of slow cooled and isothermally crystallized films decreased. The hydrolytic degradation preferentially occurred in the amorphous region. The hydrolytic degradation in crystal lamellae are mainly at the crystal surfaces.

Effects of Carbon Black Content and Vulcanization Type on Cure Characteristics and Dynamic Mechanical Property of Styrene-Butadiene Rubber Compound

The influences of carbon black loading and cure type on the cure characteristics including kinetics and dynamic mechanical properties were investigated for a styrene-butadiene rubber (SBR). The rate constants of accelerated sulfur vulcanization reaction at three different temperatures were determined using a cure rheometer, and they were compared with those from the direct measurement of sulfur concentration. The strain softening behavior under dynamic deformation, known as the Payne effect was also discussed depending on the carbon black loading and cure type.

Degradation of Polystyrene in Supercritical n-Hexane

Degradation; Polystyrene; Supercritical n-Hexane; Pyrolysis

Degradation of polystyrene was carried out in supercritical n-hexane under reaction temperature ranging from 330 ℃ to 390 ℃, pressure ranging from 30 bar to 70 bar and reaction duration of 90 min. The conversion of polystyrene increased with rising temperature and pressure. The degradation performance was influenced by the temperature rather than applied pressure. Polystyrene rapidly degraded in 30 min after reaching a prescribed temperature ranging from 350 ℃ to 390 ℃. At a prescribed temperature of 390 ℃, the degree of degradation was higher than 90%. The degradation reaction was examined experimentally at a relatively low temperature of 330 ℃. The degradation of polystyrene by using supercritical n-hexane has been found to be more effective compared to general pyrolysis (thermal degradation). Among the selectivity of liquid products, that of a single aromatic ring group like styrene at 390 ℃ increased up to 65% in 90 min. It was found from the analysis by a gel permeation chromatograph (GPC), that high molecular-weight compounds decreased but oligomers; increased with rising temperature.

Degradation of High Density Polyethylene, Polypropylene and Their Mixtures in Supercritical Acetone

Degradation; Supercritical Acetone; High Density Polyethylene; Polypropylene

The degradation of high density polyethylene (HDPE), polypropylene (PP) and their mixtures was carried out in supercritical acetone under the reaction temperature ranging from 450 ℃ to 470 ℃, pressure ranging from 60 atm to 100 atm and reaction duration time as 60 min. The yields of gas, oil and wax components and the compositions and distributions of liquid-like products were measured by means of gas chromatography and gas chromatography/mass spectrometer. In every run, the reaction was completed in 30 min after reaching the prescribed temperature. The yields of oil and gas degraded from PP were not greatly influenced by the temperature, whereas in HDPE, the yields of oil decreased and that of gas increased, respectively, with rising temperature. The yields of oil from HDPE and PP increased with increasing pressure up to 7 atm and the values under higher pressure remained almost constant, i.e., 88% for HDPE and 96% for PP. Correspondingly, the yields of wax from HDPE and PP decreased with increasing pressure below 75 atm and above the value they remained almost constant, especially zero with PP. Generally, the degradation performance was influenced by the temperature rather than applied pressure. For the degradation of mixtures of HDPE and PP, with increasing PP composition, the yield of oil increased, whereas that of wax decreased, and above 80% of PP composition, it decreased to zero. For example, the yields of oil, wax and gas from a 52 wt% HDPE~48 wt% PP mixture, amounted to 90 wt%, 1 wt% and 9 wt%, respectively. The yield of wax decreased with increasing PP percentage.

Bulky Side Group을 갖는 폴리벤즈이미다졸의 합성

polybenzimidazole; aromatic nucleophilic substitution reaction; heat resistant polymers

Novel monomer for polybenzimidazole was prepared and polymerized via aromatic nucleophilic substitution reaction. Thus, N-(4-fluorobenzoyl)-4-methoxy-N'-naphthyl-1,2-phenylenediamine was synthesized from the reaction of 4-methoxy-Nnaphthyl-1,2-phenylenediamine and 4-fluorobenzoyl chloride. N-(4-fluorobenzoyl)-4-methoxy-N'-naphthyl-1,2-phenylenediamine was converted to 2-(4-fluorobenzoyl)-5-hydroxy-1-naphthylbenzimidazole by ring closure and demethylation reaction. Polymerization was done in N-cyclohexyl-2-pyrrolidinone (CHP) containing potassium carbonate. The resulting polymer was soluble in N-methyl-2-pyrrolidinone (NMP) and had inherent viscosity of 0.38 dL/g (NMP at 30 ℃). The glass transition temperature (Tg) of the polybenzimidazole was 270 ℃. The thermogravimetric analysis (TGA) thermograms of this polymer showed 5% weight losses at 550 ℃ in nitrogen and at 540 ℃ in air.

일라이트와 몬모릴로나이트에 대한 수용액상에서의 유로퓸과 토륨의 흡착특성

Europium; Thorium; Illite; Montmorillonite; Adsorption

The adsorption characteristics of europium and thorium on clay minerals such as illite and montmorillonite were investiated by batch experiments. The adsorbed amount of Eu was constant as a function of pH and much affected by a Ca²⁺ ion at pH below 6. This means the Eu adsorption at low pH is described by ion-exchange reaction. The adsorbed amount was increased rapidly in the range of pH 6-8, which corresponds to pH edge. The adsorbed Eu was more than 95% of total Eu at pH above 8. The Eu adsorption at high pH is caused by the surface complexation reaction between Eu³⁺ or europium carbonates and minerals. The adsorbed amount of Th was sharply increased in the range of pH 3-5. Th adsorbed Th was more than 99% of total Th at pH above 5. The Th adsorption is mainly due to the surface complexation of Th⁴⁺ or thorium hydroxides. The adsorption characteristics of Eu and Th on illite and montmorillonite is represented by Langmuir adsorption isotherm. The maximum adsorbed amount of Eu and Th on illite, resulted from adsorption isotherm, is 32 and 109 meq/100 g, respectively. The maximum amount of Eu and Th on montmorillonite is 95 and 128 meq/100 g, respectively. The Eu-species calculated by MINTEQA2 are Eu³⁺, EuOH²⁺, EuCO₃⁺ and Eu(CO₃)₂^-. The Th exists in the species of Th⁴⁺, Th(OH)₂²⁺, Th(OH)₃⁺ and Th(OH)₄ in the aqueous phase.

분무 건조에 의해 생성된 원료 입자로부터 유리 중공구체의 제조에 관한 연구

Hollow Glass Spray Dryer; Borci Acid

Hollow glass spheres were prepared by using spray dryer and gas flame furnace. To fabricate the precursor particles for preparing HGS, spray dryer method was used. Operating conditions of the spray dryer for precursor particles were sample flow rate 700 ml/h, spray air pressure 100 kPa, outlet temperature 100℃ and inlet temperature 200-250℃. Also we checked the properties of the HGS according to the weight of boric acid. As a results. we found that the chemical durability and crush strength increased with increasing the weight of boric acid. The results also showed that the particle size of the HGS increased until the weight of the boric acid reached to 20 g.

폐프린트배선기판(PCBs)과 폐점퍼의 열분해 및 연소 특성에 관한 연구

Printed Circuit; Boards(PCBs); Waste Bumper; Pyrolysis; Combustion

The pyrolysis and combustion characteristics of printed circuit boards(PCBs) and waste bumper have been studied by using thermogravimetry(TG), gas chromatograph-mass spectrometry(GC-MS) and fourier transform infrared spectroscope(FT-IR). To obtain the information on the kinetic parameters of thermal decomposition of PCBs and waste bumper, the dynamic thermogravimetric analysis curve and its derivative have been analyzed by Flynn-Wall, Coats-Redfern and Ozawa methods. From the kinetic analysis, the apparent activation energies of waste bumper in air atmosphere are lower than those in nitrogen atmosphere while the apparent activation energies of PCBs are little effected by atmosphere. From the products analysis, the products from the pyrolysis and combustion of PCBs and waste bumper are mainly composed by gaseous products. As the concentrations of oxygen increases, an decreasing tendency of the yield of residue from PCBs is observed. The aromatic compounds of liquid product increase as decreasing the temperature because the gas product such as ethene, propene and butadiene are combined by the Diels-Alder reaction. To verify the possibility for the recycling of residue from pyrolysis and combustion, the resulting residue of PCBs has been analyzed for their surface area and adsorption total pore volume.

회분과 반회분 공정에 의해 생성된 실리카 미립자의 특성 비교

Silica Fine particles; Semibatch; Batch; Hydrolysis

Silica fine particles were synthesized from the hydrolysis of Si(OC₂H₅)₄ by using a semibatch process in order to overcome difficulties in production of fine particles by a batchwise reaction. To predict the particle size distribution, mean particle size and the yield of silica fine particles prepared by using a semibatch and a batch process, in this work, nondimensional reaction rate equations for TEOS, Si(OH)₄ and SiO₂ of each system were suggested. The change of the concentration with time and the yield, therefore, were compared, respectively. As a result of the test, silica fine particles obtained by semibatch process were better than those prepared from batch system in particle size distribution, yield and mean particle size. Especially, it was found that semibatch process was a successful method for controling the size, i.e., a narrow distribution of a particle size which ranges to several microns. Also the theoretical results for the yield were in good agreement with the experimental data.

황화된 다공성 아연계 흡착제의 산화적 재생반응에 관한 연구

H₂S; Regeneration; Zinc-based Sorbent; Metal Oxide

In order to develop sorbents for the removal of hydrogen sulfide contained in coal-derived gas, additives such as CaO, Li₂O and TiO₂, were added to zinc oxide and the reactivity and kinetics of the oxidative regeneration for the sulfided porous zinc-based sorbents were examined. At 600-700℃ the initial reaction rate of these sorbents increased with increasing the reaction temperature and the effect of total gas flow rate on the reaction above 100ml/min showed similar behavior. Also it was revealed that only the 2.0 at% TiO₂-doped ZnO sorbent promoted oxidation rate of pure zinc sulfide from the investigation of the effect of additive on regeneration. In this study Avrami equation was appropriate to interpret the kinetic data obtained from oxidation. The oxidation rate constant was expressed as k=2.07×10¹²exp(-27170/T) and the activation energy of oxidation was 54.06kJ/mol.

Synthesis of Monodisperse SiO2 and TiO2 Nanoparticles using Semibatch Reactor and Comparison of Parameters Effecting Particle Size and Particle Size Distribution

SiO2; TiO2; Nanoparticles; Monodisperse; Semibatch

Monodisperse SiO2 and TiO2 nanoparticles were synthesized from tetraethyl orthosilicate (TEOS) and tetraethyl orthotitanate (TEOT) dissolved in ethanol, respectively, using a semibatch method which was found to be easier than a batch process in controlling the size, shape, and size distribution In this study, a statistical experimental method was also used to compare the properties (particle size and standard deviation) of the SiO2 and TiO2 particles according to four parameters [R(=H2O/TEOS or TEOT), hydroxypropylcellulose (HPC)/ NH3, the feed rate of the reactant, and the reaction temperature]; It was found that the optimal conditions for the preparation of SiO2 and TiO2 nanoparticles in a semibatch process were as follows.; (1) SiO2; R(=[H2O/TEOS]): 31, concentration of ammonia: 0.32 mole/1, feed rate of reactant: 17 ml/min, reaction temperature: 62 ℃, (2) TiO2; R(=[H2O/TEOT]): 16, HPC: 0.0028 g/ml, feed rate of reactant: 0.6 ml/min, reaction temperature: 30 ℃. Using the above optimal conditions, particles of SiO2 (13.7 nm) and TiO2 (10.6 nm) with a narrow size distribution were prepared. In addition, it was found that the main parameters affecting the preparation of SiO2 and TiO2 nanoparticles decreased in the order of the feed rate of the reactant > NH3/ HPC > R (=H2O/TEOT) > the reaction temperature.

Formation of Monodisperse TiO2 Nanoparticles Generated without HPC Dispersant by Controlling Reaction Method and Temperature

TiO2; Nanoparticles; Monodisperse; Dispersant

Monodisperse TiO2 nanoparticles were synthesized from tetraethyl orthotitanate (TEOT) dissolved in ethanol using a semibatch method, which is easier than a batch process in controlling the size, shape, and size distribution, without the addition of HPC. In this semibatch system, the preparation conditions of a low flow rate (1.1 cc/min) and high reaction temperature (70 ℃) were applied to produce monodisperse nanoparticles. As a result, the smallest size nanoparticles (∼12.7 nm in diameter) with a narrow size distribution were produced. Tn addition, it was found that the semibatch reaction had an advantage of a short nucleation due to the repetitive addition of the TEOT solution and a high temperature, at which point the solubility of the solute increased, thereby decreasing the particle size. In conclusion, the efficacy of nanoparticle synthesis was established by controlling the reaction method and temperature.

Optimal Conditions for Formation of TiO₂ Nanoparticles Using Semibatch-Batch Two-Stage Mixed Reaction Method

TiO₂; nanoparticles; semibatch-batch; optimal condition

TiO₂ nanoparticles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol using a semibatch-batch two-stage mixed method. In this work, a statistical experimental method was used to compare various properties of TiO₂ particles according to six parameters [concentration of TEOT during 1^st and 2^nd stages, reaction temperature during 1^st and 2^nd stages, and amount of hydroxypropyl cellulose (HPC) during 1^st and 2^nd stages]. It was found that the optimal conditions for the preparation of TiO₂ nanoparticles using this method were as follows; (1^st TEOT (M): 0.08~0.10, 2^nd TEOT (M): 0.13~0.15, 1^st Temp. (℃): 15~20, 2^nd Temp. (℃): 35~40, 1^st HPC ((X10^-2 g/cc): 0.015~0.019, 2^nd HPC ((X10^-2 g/cc): 0.25~0.30). The experimental results using the above optimal conditions were in agreement with the theoretical data and produced the smallest size (~30 nm in diameter). In addition, it was found that the main parameters affecting the preparation of TiO₂ nanoparticles were the concentration of TEOT and reaction temperature during the second stage.

Swelling Behavior of Polyurethane Hydrogels Based on Poly(ethylene oxide) glycol (PEG) or Poly(ethylene oxide-co-propylene oxide) glycol (PEPG)

polyurethane hydrogel; swelling behaviors; interaction parameter; PEG

PEG-based and PEPG-based polyurethane (PU) hydorgels were prepared using various ratios of ethylene oxide (EO)/propylene oxide (PO) and their swelling behaviors inverstigated. The PEG-based PU hydrogels showed a continuous volume transition with temperature. In contrast, The swelling behaviors of the PEPG-based PU hydrogels with a higher PO content exhibited a more sensitive volume transition than those of the PEPG-based PU hydrogels with a lower PO content. In a pulsatile swelling behavior experiment, the swelling-deswelling rates of the PEG-based PU hydrogels were constant regardless of the PEG molecular weight. In contrast, swelling-deswelling rates of the PEPG-based hydergels with a higher PO content were faster than those of the PEG-based PU hydrogel. This suggests that PO increases the hydrophobicity of the gel. Flory''''s interaction parameter,χ, was employed to characterize the relative solvent-polymer interaction. There are two contributions to the interaction parameter,χ, the entropic (χ_S) and the enthalpic (χ_H) contribution. The result of this study showed that the major contribution to the polymer-water interaction parameter χ_S.

자외선 방전을 이용한 SO2 제거용 광화학 반응장치에 대한 연구

Ultraviolet lamp; SO2; Photochemical reactor; Baffle

In this study, the possibility of ultraviolet photochemical reactor using ultraviolet radiation, which is induced by a vaccum ultraviolet lamp, was examined for the removal of SO2 from flue gas. The experiment was carried out by type A lamp, which had the best performance among several lamps studied. Reactor volume was 16 L, and in the reactor, baffles were installed for effective flow control of SO2 removal. The SO2 removal characteristic was studied at the temperature range of 25 ∼50 ℃ and SO2 concentration range of 1000∼5600 ppm. To study the water effect, water content of 3 vol% was added into reactor. In the result of simulated gas, SO2 removal was 1200∼1800ppm.

전기투석에 의한 아연 정련공장 폐수로부터 아연과 황산의 회수[1]-확산투석

Diffusion dialysis; Flux; Anion exchange membrane; ZnSO4; H2SO4

As a preceding step for the separation of ZnSO4 and H2SO4 from zinc refinery waste water using electrodialysis, diffusion dialysis was performed. Neosepta ACM anion exchange membrane is superior to ESC 7001 in the acid dialysis. The complete separation between ZnSO4 and H2SO4 can be practicable, and the maximum flux for H2SO4 is 2.728×10(-8) mol·cm(-2)·s(-1). The presence of ZnSO4 does not significantly affect the H2SO4 flux.

폐타이어로부터 회수한 카본블랙을 이용한 폴리스티렌으로부터 스티렌 단량체의 회수

Polystyrene; Pyrolysis; TCB(tire pyrolytic carbon black); Monomer

Characteristics of oil products from thermal degradation of polystyrene were studied by using pyrolytic carbon black of waste tire as the recycling adsorbent. Pyrolysis experiments were performed with various temperatures (25∼500 ℃) and amounts of TCB loaded (10∼100 wt%). The recovered oil products were studied using gas chromatography-mass spectrometry (GC/MS) and gas chromatography (GC). From the experiments, it was found that the optimal condition for the maximum purity of monomers on the recovered oil products was approximately at 100 ℃ and 40 wt% TCB loaded. The recovered oil products were composed mainly of styrene monomers, and their purity can be 30% higher than those without the treatment of PS pyrolysis. From the analysis of adsorption compounds in packed bed, TCB has shown to be a good adsorption material for di-aromatics and tri-aromatics of PS pyrolytic gas at 100 ℃.

Poly(4-vinlpyridine)과 3-Pentadecylphenol로 이루어진 Molecular Bottle-Brush의 Order-Disorder Transition에 미치는 용매효과

Molecular bottle-brush; Poly(4-vinylpyridine); 3-pentadecylphenol; Order-disorder transition

Molecular bottle-brush was prepared by hydrogen-bonding between poly(4-vinylpyridine) (P4VP) and 3-pentadecylphenol (PDP). The phase behavior and mesomorphic structure of bottle-brush in the bulk, heptane, toluene, and xylene were investigated by changing the mole ratio of P4VP and PDP (x). Thermal-optical microscopy analysis (TOA) and differential scanning calorimetry (DSC) demonstrated that bottle-brushes, in the bulk, formed a disordered melt at temperatures above the order-disorder temperature (T(ODT)); whereas at T < T(ODT) an ordered-microphase separated structure was observed. Further cooling rendered the side-chain crystallization. However, in the solvent-bone bottle-brush system, T(ODT) and the temperature of side-chain crystallization (T(c)), i.e., the phase transition temperatures, were lowered by adding a solvent. And it was found that the phase behavior of these bottle-brushes was affected by the miscibility between the solvents and PDP.

혼합 용매내에서 단분산 Al2O3 미립자 생성을 위한 합성 조건의 결정

Al2O3; Monodispersed; Dispersant HPC

To obtain the unagglomerated and monodispersed Al2O3 fine particles and to control the hydrolysis rate of Al(sec-OC4H9)3, hydrophilic acetonitrile and hydrophobic n-octanol were used. The dispersant HPC(hydroxypropylcellulose) was also added to the mixture to prevent the aggregation. Synthetic condition of mono-dispersed Al2O3 fine particle was 0.05M Al(sec-OC4H9)3, 0.1M H2O, 50 vol% n-octanol, 40 vol% acetonitrile, 10 vol% ethanol, 10 ℃ reaction temperature and 0.1×10(-3) g/cc HPC concentration. The zeta-potential value of emulsion droplets and particles was near zero charge, but the dispersions were stabilized by steric repulsion effect due to addition of HPC. The Al2O3 particle size was unaffected by the reaction temperature, the amount of HPC added, and the concentration of reactants.

산 및 염기 촉매하에서 W/O 마이크로 에멀젼법을 이용한 실리카 나노 입자의 제조

silica; microemulsion; base catalyst; acid catalyst

In this paper, we obtained nanosized silica particles in W/O microemulsion by reaction of tetraethyl orthosilicate, using either NH₃, HCl, or HNO₃ as a catalyst. When a base catalyst (NH₃) was used, silica particles had a mean size of 10.5 nm. As water concentration increased, the size of silica decreased, while it increased with increasing NH₃ concentration. Through the ternary phase diagram it was confirmed that HNO₃-based microemulsion has higher water solubility than HCl-based microemulsion at high temperature. With increasing temperature, the mean size fo HNO₃-based silica particle increased, but the mean size of HCl-based silica particles increased until 25℃ and decreased slowly thereafter. The yield was higher with HCl as a catalyst than with HNO₃ and a perfect yield of 100% was obtained at 40%.

폴리우레탄/Clay 나노복합재료의 제조 및 물성에 관한 연구

polyurethane; organoclay; nanocomposite; reinforcement

Polyurethane/clay nanocomposites were prepared from polytetramethyleneglycol (PTMG), trifunctional polyisocianate and long-chain onium ion exchanged montmorillonite. When clay content is 20wt%, the PU/clay nanocomposite become a transparent film and showed a two-fold increase in tensile strength, modulus and elongation at break compared to the unfilled PU. Also thermal decomposition temperature, dynamic storage modulus was greatly enhanced, and the temperature at which tan δis maximum ws increased in the PU/organoclay nanocomposite. Fracture surface of the PU/clay composite observed by SEM indicated an enhancement of fracture resistance. It was judged that the initial gallery height and modifier content in the silicate layers should have an optimum value for the maximum reinforcement of the composite.

불소 변성 폴리우레탄의 합성과 표면 개질; II. 폴리올 구조와 분자량의 영향

fluorine modified polyurethanes; surface energy; degree of surface arrangement of fluorine; incompatibility

Fluorine modified diisocyanates (FMD) was synthesized from tris(6-isocyanatohexyl)isocyanate (TIHI) and N-ethyl-N-2-hydroxyethyl-perfluoroctanesulfonamide(HFA). Then fluorine modified polyurethane (FMPU) was synthesized from FMD and two type polyols, polyehter and polyester, which had molecular weight of 2000 g/mol and 1000 g/mol respectively. To observe the effects of polyol structure and molecular weight on the surface energy of blended polyurethane, the FMPU was mixed into the polyester type polyurethane which is commonly used in artificial lether manufacturing. The surface energies and the thermal properties of the blended PU film were measured by a contact angle meter and DSC. The film morphology of cross section was observed by SEM. The surface energies of of blended PU decreased with decreasing the molecular weight of polyols. This result indicates that the improved surface arrangement of fluorine was caused by the decrease molecular weight of polyol. The surface energies of blended PU with polyester type FMPU showed lower value than that of polyether type FMPU, due to the limited degree of surface arrangement of fluorine caused by the incompatibility between polyether polyol and polyester polyol. Using DSC and SEM, a phase separation of FMPU was observed when the fluorine content was 0.573 wt%.

Calfgur과 Kip혁의 제조에 관한 연구(II) -나피로부터 도장혁 제조-

bio-tech treatment; calf- and kip-pelt; aniline-type leather; calf and kip leathers

This study concerns the standardization of the manufacturing process of high quality leathers from Calf- and Kip-pelt unhaired by bio-tech treatment. The mechanical properties of Calf- and Kip-finished leathers manufactured by the detail conditions of this study met the requirements of the Korean Industrial Standard (a tensile strength of 1.2kg_f/㎟, an elongation of 30%, a tear strength of 3.0kg_f/mm, a grain crack weight of 15kg_f, and a Cr₂O₃ content of 2.5%). Therefore, it is expected that these manufacturing conditions will be very important guides in the study of standardization of aniline-type leather manufacturing process of Calf- and Kip- leathers. Besides, the quality control of the final leather might be possible by employing SEM and analyzer in examining grain surface, cross section, and pores condition of the wet blue and the crust leather after being pelted.

Calf혁과 Kip혁의 제조에 관한 연구(I) -나피 제조공정 중 탈모조건의 영향-

calf skin; kip skin; unhairing process; bio-tech treatment; pelt

This study investigates how pelt-states resulting from different unhairing methods would affect the manufacture of high quality Calf and Kip skin shoe leather. It was found that an unhairing process affected pelt manufacture most significantly. Among chemical treatment, enzymatic treatment, and bio-tech treatment applied to unhairing, bio-tech treatment was the most efficient. Moreover, this unhairing process was effective when addition of 3 times amount of water, 4% Ca(OH)₂ and 0.5% Lupin LE-10 agent based on weight of raw skin, and successive treatment around 25℃ for 18 hours were applied. The unhairing rate of Kip skin was lower than that of Calf skin. However, in terms of fiber separation, the Kip skin was favorable than the Calf skin. To obtain more precise scientific information on pelt-state, new analytical instruments such as Scanning Electron Microscopy and Image Analyzer together with the conventional sensual tests were utilized.

혼합용매내에서 단분산 Al₂O₃ 미립자의 합성에 대한 전해질 첨가 효과

emulsion; method; hydrophilic; hydrophobic; monodispersed

To obtain unagglomerated, narrow size distributed, and monodispersed Al₂O₃ fine particles from Al(sec-OC₄H₉)₃, emulsion method was used. Acetonitrile as a hydrophilic solvent and n-octanol as a hydrophobic solvent were used in order to control the hydrolysis rate of Al(sec-OC₄H₉)₃. Electroytes were added in mixed solvent to prevent the fine particles from aggregating and its effect was investigated. It was found that optimal synthetic conditions of monodispersed alumina fine particles were 0.05M Al-alkoxide, 0.1M H₂O, 50 vol% n-octanol, 40 vol% acetonitrile, 10 vol% ethanol, and 10^-2 M HCI under 10℃ reaction temperature.

알콕 사이드로부터의 실리카 미립자 합성에 알코올 용매의 종류가 미치는 영향

silica; alcohol solvent; size distribution

In this paper, we investigated the effect of alcohol solvents (ethanol, n-propanol, and n-butanol) and isomeric alcohol solvents (iso-propanol, iso-butanol, sec-butanol and tert-butanol), In addition, we observed the effect of the mixed alcohol solvents on the particle formation as using a mixture of ethanol and butanol at a ratio of 30/70, 50/50, and 70/30 vol%, respectively. In case of ethanol solvent, particle size of silica showed the smallest and the narrowest size distribution among the various solvent. On the contrary, for the n-butanol solvent, largest broad distribution of particle size was observed. For the synthesis of particles having better spherical morphology and less agglomeration, alcohol solvent having no branches was considered appropriate. When mixed alcohol solvents were used, large silica particles with narrow size distribution were obtained, regardless of the ratio.

실록산을 함유한 지방족 폴리에스테르의 합성 및 특성에 관한 연구

siloxane block; aliphatic polyester; condensation polymerization; contact angle; ESCA

Poly(hexylene-co-PDMS succinate), aliphatic copolyesters containing siloxane block, were synthesized by a condensation polymerization using 1,6-hexanediol and hydroxy terminated polydimethylsiloxane as diols and succinic acid as dibasic acid. As siloxane content in the copolymer increased, glass transition temperature and melting temperature of the copolyesters were reduced. And, with the increase in the siloxane content in the copolymers, there was a decrease in tensile strength and increase in elongation at break. Contact angle against water indicated that as the PDMS content in the copolymer was increased, hydrophobicity of the surface of the copolyesters increased. ESCA results indicated that PDMS segments were predominating at the outer surface of the copolyesters.

Kinetic Analysis of Thermal Decomposition of Polymer Using a Dynamic Model

Thermal Decomposition; Kinetic Analysis; Dynamic Method; Polyethylene

The objective of this work was to develop a kinetic analysis method by using a dynamic model that accounts for the thermal decomposition behavior of polymers with the variation of the conversion. The proposed method was applied to predict the thermal decomposition of polyethylene. The kinetic analysis was studied by conventional thermogravimetric technique with various heating rates in nitrogen atmosphere. To verify the appropriateness of the proposed method, the results from this work were compared with those of various analytical methods and the literature. The TG data were also compared with the values calculated by using the kinetic parameters from the dynamic method. It was found that the dynamic method gave a reliable value of kinetic parameters, and the activation energy and the reaction order of thermal decomposition of high-density polyethylene were larger than those of low-density and linear low-density polyethylene.

Thermal Fatigue-Resistant EMCs (Epoxy Molding Compounds) for Microelectronic Encapsulation

Thermal Fatigue; Thermal Conductivity; CTE; Alumina and EMCs

Highly thermal conductive EMCs (Exopy Molding Compounds) should be considered for the alleviation of thermal stress-related problems caused by low thermal conductivity, and high elastic modulus of EMCs and by a mismatch of CTE (Coefficient of Thermal Expansion) between EMCs and the Si-wafer. Compared to crystalline silica-filled EMCs, alumina filed EMC improved the value of thermal conductivity by 100% and lowered the value of CTE by 50%. As a result, compared to typical crystalline silica-filled EMCs, the thermal fatigue resistance of alumina-filled EMC was improved by sixfold.

Effect of the Reaction Bath Temperature in a Fixed-bed Reactor for Oxidation of o-Xylene over V₂O₅/TiO₂ Catalysts

Fixed-bed Reactor; o-Xylene Oxidation; Reaction Variables; Heat Effect; Temperature Profile

The effects of the reaction variables in the operation of a fixed-bed reactor for oxidation of o-xylene over V₂O₅/TiO₂ catalysts were studied experimentally using a bench reactor. Reaction temperature, feed flow rate and feed concentration of o-xylene were found to have significant effects on the products distribution and the temperature profile in the reactor. Drastic enhancements of 0-xylene oxidation reaction were observed at some conditions, which was ascribed to the effect of heat accumulated in the bed and indicated a possible way to increase the productivity in the industrial condition.

Pyrolysis Characteristics of Acrylonitrile-Butadiene-Styrene Resin

pyrolysis; ABS resin; kinetic analysis

The pyrolysis characteristics of acrylonitrile-butadiene-styrene resin were investigated at various heating rates. Methane, ethane and ethylene were major gaseous products from pyrolysis of acrylonitrile-butadiene-styrene resin. The recovered oil products were mainly composed of styrene monomer and benzene, and showed the calorific value of 8400∼9000 cal/g, which may be suitable as fuel oil. In order to obtain the kinetic parameters of ABS pyrolysis, the dynamic thermogravimetric analysis curve and its derivative have been analyzed using a variety of analytical methods reported in the literature.

Degradation of Polystyrene in Supercritical Acetone

supercritical fluid; acetone; degradation; polystyrene

The degradation of polystyrene(PS) in supercritical acetone was carried out in the temperature range of 260 to 300 ℃ using a batch type autoclave reactor. The total conversion rapidly increased with the increase of temperature from 270 to 290 ℃. The yield of non-aromatic condensates and the total conversion were affected little by the acetone density, which considerably influenced the product distribution. The yield of styrene was the highest among other products, when the weight ratio of acetone to PS was fixed at 11.2, which was equivalent to acetone density 0.406. The yields of styrene and diphenylbutene (equivalent to dimer of styrene) attained maximum values at a temperature in between 280 and 290 ℃.

Effects of Anionic Center on Properties of Polyurethane Anionomer Dispersion

polyurethane dispersion (PUD); anionic center; state of dispersion; thermal properties; mechanical properties

Polyurethane anionomer dispersions (PUDs) were prepared from 4,4-dicyclohexylmethane diisocyanate, poly (tetramethylene glycol) and diol bearing pendant carboxylic acid. The type and concentration of diol were varied in order to investigate the influence of anionic center on state of dispersion, morphology and mechanical properties. The diols used in this study were dimethylol propionic acid, THPP-MA and THPP-PA which were synthesized from the esterification reactions of 1,2,3-tri (2-hydroxypropoxy) propane (THPP) with maleic anhydride (MA) and phthalic anhydride (PA), respectively. The particle size of PUD was observed to be dependent on the molecular structure of anionic center, even though it was largely governed by the concentration of acid group. This was attributed to the fact that hydrophilicity of PU ionomer at a given ionic concentration was increased with the flexibility of anionic center, which was in the order of THPP-MA > THPP-PA > dimethylol propionic acid. Surface tension and water swelling were also higher for the PUD with more flexible acid group. The morphological property of PUD film was characterized by DSC. These variations in phase morphology were reflected in the tensile properties of PUD films.

Biodegradable Polymer Blends of Poly(lactic acid) and Starch

Poly(lactic acid)(PLA) and starch were melt-blended using a twin screw mixer. To improve the toughness of blends, poly(ε-caprolactone)(PCL) was added up to 30wt%. Blends were characterized by DSC thermal analysis, tensile test, morphological analysis and ATR IR spectroscopic analysis. The addition of starch gave little influence on thermal properties. In particular, at the starch content of 5 wt%, the crystallinity of PLA were the highest. The addition of starch resulted in reducing the tensile strength and elongation ratios, PCL was found to be effective in improving toughness. ATR IR spectra showed that the C=O band of PLA shifted when starch was added, indicating that some hydrogen bonding formed between the ester group of PLA and the hydroxyl group of starch. Morphological results by polarized optical microscopy showed that the size of the spherulite became smaller and less regular as the content of starch increased