| Summary: | 碩士 === 國防大學中正理工學院 === 應用化學研究所 === 90 === In order to improve the polymer lifetime used in the military, a novel large molar mass phenolic phosphite antioxidant, tetrakis-(2,5-di-tert-butyl- 4-hydroxyphenyl)-2,5-di-tert-butyl-hydroquinonediyl diphosphite (2P5B), was prepared and characterized by IR, 31P NMR, FAB-MS and thermogravimetric analysis (TGA).
The effect of 2P5B content on the thermal property of the poly(methyl methacrylate) (PMMA) was studied by TGA, differential scanning calorimeter (DSC), and oxidative induction time (OIT). The 2P5B antioxidant is more efficient than Irganox 1010 and Irgafos® 168 at high temperature(280 ℃). The 0.5 wt % of the novel phenolic phosphite antioxidant retarded the 10 % weight loss temperature and reduced the maximum rate of weight loss. The stabilized-PMMA existed a clear OIT onset that increased with increasing 2P5B content. The apparent activation energies for initial thermo-oxidative degradation, evaluated by van Krevelen method, of the stabilized-PMMA were less than that of antioxidant free PMMA. Hence, it seems reasonable that the PMMA was degraded easily as the antioxidant was consumed.
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