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.
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