Thermal degradation of some siloxane-grafted poly(methyl methacrylate)s

Thermal degradation of polymethylphenylsiloxane-poly(methyl methacrylate) g raft copolymer (PSXE-g-PMMA) was studied by using thermogravimetric analysi s (TGA), and compared with unmodified poly(methyl methacrylate) (PMMA). The deconvoluted differential thermal gravimetry (DTG) curve of PSXE-g-PMMA cl early showed four peaks, and that of PMMA showed three peaks. The temperatu re of maximum weight loss increased with increasing polymethylphenylsiloxan e (PMPS) content, whereas the rate decreased. The apparent activation energ y E-a of thermal degradation was evaluated by different methods. The value of E-a for MMA segments in PSXE-g-PMMA was larger than that for PMMA. (C) 1 999 Elsevier Science Ltd. All rights reserved.