Study of the thermal behaviour of poly(methyl methacrylate) initiated by lactams and thiols

摘要

Thermal degradation of traditional poly(methyl methacrylate) (PMMA) results in the evolution of MMA monomer with two steps including end group scission and C-C chain homolysis by random scission. PMMA initiated by lactams and thiols has higher thermal stability and shows only C-C chain homolysis by random scission. The observed results are explained by a "blocking effect". Three kinetic analysis methods have been used to describe the thermal degradation behaviour measured by weight loss. The Flynn method shows activation energy of 116-128 kJ/mol, higher than that of AIBN initiated poymer (78-91 kJ/mol). According to the Ozawa method the average activation energy is 222-236 kJ/mol, higher than other PMMA systems (126-169 kJ/mol). Finally, the method of Kissinger shows that this system has a frequency factor four orders of magnitude higher than conventional PMMA. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 33]