Elsevier

Thermochimica Acta

Volume 525, Issues 1–2, 20 October 2011, Pages 9-15
Thermochimica Acta

Synthesis and degradation kinetics of a novel polyester containing bithiazole rings

https://doi.org/10.1016/j.tca.2011.07.015Get rights and content

Abstract

A novel Schiff base type polyester containing 2,2′-diamino-4,4′-bithiazole (DABT) was prepared by low-temperature interface polycondensation of 1,4-benzenedicarbonyl dichloride with 4,4′-(4,4′-bithiazole-2,2′-diylbis(imine-2,1-diyl) diphenol (BDDP), which is derived from a 2,2′-diamino-4,4′-bithiazole (DABT) Schiff base reacted with a 4-hydroxybenzaldehyde monomer. The newly generated polyester was characterized by FTIR spectroscopy, elemental analysis, and X-ray diffraction spectroscopy. The thermal decomposition was investigated in nitrogen atmosphere using thermogravimetric analysis. The activation energies of the decomposition step of the polyester were calculated through the isoconversional methods of Kissinger–Akahira–Sunose (K–A–S) and the iterative equation. In order to estimate the reaction model that best describes the experimental data, the use of an empirical kinetic equation based on that proposed by Sestak–Berggren was investigated here. On the basis of the kinetic data, the life time estimates for the polyester generated from the weight loss of 5%, 10%, and 15% were also constructed.

Highlights

► A novel Schiff base type polyester was synthesized and characterized by FTIR spectroscopy, elemental analysis, and X-ray diffraction spectroscopy. ► Thermal degradation of the polyester in nitrogen has been studied at several heating rates by thermogravimetric analysis. ► The activation energies were calculated by different methods. And the possible conversation function was estimated. ► The life time estimates for the polyester can be determined and the results demonstrate that the polymer possesses good thermal resistance.

Introduction

The field of organometallic polymers is attracting the interest of researchers due to the fact that metal-containing polymers may possess more special properties than conventional organic polymers. In 1998, Hoffmann et al. [1] proposed that polymers built from sulphur, carbon, and nitrogen-containing five-membered rings would theoretically display magnetic ordering. Heteroaromatic cyclic complexes formed from suitable metals and organic ligands are some of the best candidates for organic magnetic materials. More recently, it was found that aromatic heterocyclic polymers containing bithiazole rings are good ligands because the two nitrogen atoms in the bithiazole rings are able to chelate metal ions to form stable five-membered rings [2].

Schiff base type polymers, which have many special properties, such as thermal stability, liquid crystalline properties, conductivity, and chelating effects [3], [4], [5], have been drawing the attention of researchers for more than 50 years. A variety of Schiff base polymers had been synthesized and characterized [6]. Sun et al. [7], [8] synthesized bithiazole-containing polymers and found their metal complexes had typically ferromagnetic properties. These polymers and their derivatives were investigated as high-performance polymers for use in ferromagnetic materials, as well as new composite and photoelectronic materials. For this purpose, the material can be subjected to high temperature not only in the manufacturing, compounding and processing stage, but also in service or during repair [9], [10]. Since thermal stability is related to both the initial temperature and the rate of degradation of polymers, determination of kinetic parameters associated with the degradation processes is an interesting topic of research. Thermal analysis can also be used for the durability assessment and lifetime prediction of the product. Such a study is very important for the improvement of the service performance of the product, especially for critical applications in defense and aerospace, which would help build up user confidence in other potential applications.

The present paper reports on the synthesis, characterization and degradation kinetics of a novel polyester containing bithiazole rings. The degradation kinetics was followed using differential thermal analysis-thermogravimetry (DTA-TG). The non-isothermal kinetics of the decomposition process of the polyester was interpreted by the integral isoconversional method suggested by Kissinger–Akahira–Sunose (K–A–S) and iterative methods that give the best description of the studied decomposition process and allow the calculation of reliable values of the kinetic parameter.

Section snippets

Materials

4-Hydroxybenzaldehyde (PHBA, purity  99%) and 1,4-dibromo-2,3-butanedione (purity 98%) were purchased from Shanghai Chemical Reagent Company. 1,4-Benzenedicarbonyl dichloride (purity  99%) and dichloromethane (purity 99.8%) were obtained from J & K Technology Co., Ltd. Thiourea (purity 99%) was obtained from Sinopharm Chemical Reagent Co., Ltd. Acetone (purity 99.3%), ethanol and NaOH (purity 98%) were supplied by Shenzhen Meryer Chemical Technology Co., Ltd.

Synthesis of polyester

In a three-necked flask equipped with

FTIR analysis

The basic strategies employed for the synthesis of a novel polyester containing bithiazole is based on the Schiff base and Schotten–Baumann reactions. The structure of the Schiff base type BDDP was determined by IR spectroscopy. The spectra of DABT, 4-hydroxybenzaldehyde and BDDP can be seen in the FTIR spectra (Fig. 3). BDDP gives characteristic peaks in the range of 1400–1550 cm−1, which are due to the bithiazole rings. The stretching vibration of the new Cdouble bondN bond appears at about 1606 cm−1 for

Conclusions

A novel Schiff base type polyester based on bithiazole has been obtained from low-temperature interface polycondensation of 1,4-benzenedicarbonyl dichloride with 4,4′-(4,4′-bithiazole-2,2′-diylbis(imine-2,1-diyl)diphenol (BDDP). The polyester was characterized by FTIR spectroscopy, elemental analysis, X-ray diffraction and thermogravimetric analysis. A broad X-ray diffraction hump indicates that the polyester has an amorphous nature. The thermal degradation of the polyester in nitrogen has been

Acknowledgements

This work was financially supported by Education Office of Liaoning Province (No. 2008567) and State Key Laboratory of Robotics (RLO201016).

References (40)

  • S. Vyazovkin

    Conversion dependence of activation energy for model DSC curves of consecutive reactions

    Thermochim. Acta

    (1994)
  • S. Vyazovkin

    An approach to the solution of the inverse kinetic problem in the case of complex processes: Part 4: chemical reaction complicated by diffusion

    Thermochim. Acta

    (1993)
  • J. Sestak et al.

    Study of the kinetics of the mechanism of solid-state reactions at increased temperature

    Thermochim. Acta

    (1971)
  • P. Simon

    Forty years of the Sestak–Berggren equation

    Thermochim. Acta

    (2011)
  • S. Vyazovkin et al.

    ICTAC kinetics committee recommendations for performing kinetic computations on thermal analysis data

    Thermochim. Acta

    (2011)
  • H. Genin et al.

    Theoretical tinkering: the search for magnetically ordered organic polymers built from sulfur, carbon, nitrogen-containing five-membered rings

    Macromolecules

    (1998)
  • C. Yelda et al.

    Conducting polymers of terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester and their electrochromic properties

    Polymers

    (2004)
  • J. Weng et al.

    Synthesis and magnetic properties of novel poly(Schiff base)–Fe2+ complexes

    Macromol. Rapid Commun.

    (2000)
  • J.P. Critchley et al.

    Heat-resistant Polymers

    (1983)
  • M. Day et al.

    The thermal stability of poly(aryl-ether-ether-ketone) as assessed by thermogravimetry

    J. Appl. Polym. Sci.

    (1989)
  • Cited by (0)

    View full text