Effect of phenolic phosphite antioxidant on the thermo-oxidative degradation of PMMA

A novel high molar mass phenolic phosphite antioxidant, tetrakis-(2,5-di-tert-butyl-4-hydroxyphenyl)-2,5-di-tert-butyl-hydro-quinonediyl diphosphite (2P5B), was prepared and characterized by IR, P-31 NMR, FAB-MS and thermogravimetric analysis (TGA). The effect of 2P5B content on the thermal properties of poly(methyl methacrylate) (PMMA) was studied by TGA, differential scanning calorimetry (DSC), and oxidative induction time (OIT). 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 showed 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 2P5B antioxidant was consumed. (C) 2002 Elsevier Science Ltd. All rights reserved.