화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.13, No.8, 809-814, December, 2002
폴리올에스테르 오일의 온도에 따른 열 안정성 및 수명 변화 특성
Thermal Stability and Lifetime Change Characteristics of Polyester Oils with Temperature
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초록
폴리올에스테르 오일 (Turbo Oil 2380)의 수명을 예측하기 위하여 열중량 분석(TGA)과 산화안정성 시험(FED-STD-791 Method 5308)을 행하였다. 공기 분위기와 등온(175, 189, 204, 218 및 232 ℃) 상태에서 시험관 TGA 분석 결과, 오일의 수명은 각각 127, 63, 33, 14 및 6 min을 나타내었다. FED-STD-791 Method 5308으로 시험한 후 시험 오일의 동점도(KV) 및 전산가(TAN)를 분석하여 오일의 수명을 예측하였으며 금속 시편의 무게 감량 및 변색 유무를 평가하여 오일의 산화과정을 고찰하였다. 첫째, 동점도 결과로 예측한 오일의 수명 (수명의 한계: 40 ℃동점도 변화량 15%)은 130 (@ 175 ℃), 38 (@ 189 ℃), 34 (@ 204 ℃) 및 14 h (@ 218 ℃)을 각각 나타내었다. 둘째, 전산가(TAN) 결과로 평가한 오일의 수명(수명의 한계: TAN 변화량 2.0 mgKOH/g)은 1346 (@ 175 ℃), 208 (@ 189 ℃), 55 (@ 204 ℃) 및 13 h (@ 218 ℃)을 나타내었다. 셋째, 촉매로 사용한 금속 시편 (INCO 625, SUS 304, AMS 4015 및 AMS 4700A)의 무게 변화량은 ±0.2 mg/cm2이내였고 SUS 304와 AMS 4700A의 색깔이 변화하였다. 색깔이 변화한 AMS 4700A를 EDX 스펙트럼으로 분석한 결과, 산화시간이 증가하고 변화한 색깔이 진할수록 탄소와 산소의 피크가 커졌으며 이것은 오일의 산화반응에 의하여 생성된 금속산화물과 유기산화물 때문이라 생각되었다.
The lifetime of polyolester oil, Turbo Oil 2380 (STD) was examined through thermogravimetric analysis (TGA) and oxidation stability experiments. The TGA experiments under air, as the carrier gas, revealed that the lifetimes of STD oil were 127, 63, 33, 14, and 6 min for the samples at 175, 189, 204, 218, 232 ℃, respectively. The oxidation stability experiments by using FED-STD-791 Method 5308 allowed us to obtain kinematic viscosity, TAN, and the weight change data of the metal specimen. The kinematic viscosity results indicated that the lifetimes of the oil (limit of life: 15% change) were 130, 38, 34 and 14 h for the samples exposed to the temperatures of 175, 189, 204 and 218 ℃, respectively. From the TAN results (limit of life: 2.0 change), it was shown that 1346, 208, 55 and 13 h were the lifetimes for the sample under 175, 189, 204 and 218 ℃, respectively. It was also observed that the weight change of metal specimens was less than 0.2 mg/cm2. In addition, it was found that the oxidation process changed the colors of SUS 304 and AMS 4700A. To analyze the chemical composition of the color-changed surface, an EDX technique was used. In the EDX spectra, it was observed that the peaks of C and O increased with increasing oxidation time. This implies that the changes in color of the metal surface were due to the accumulation of metal oxides and oxidized organic compounds on the surface.
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