Thermal degradation of poly(methyl methacrylate) (PMMA): modelling of DTG and TG curves

The thermal behaviour of poly(methyl methacrylate) (PMMA) with average molecular weights of 996,000 and 350,000 g mol−1 was investigated by thermogravimetric analysis in dynamic conditions at four different heating rates: 2, 5, 8 and 10 K min−1. In inert atmosphere, four degradation steps were found to be involved supporting the degradation behaviour previously investigated in the literature. Assuming four independent reactions, the apparent kinetic parameters were determined for each step using a non-linear fitting algorithm allowing us to simulate the overall weight loss of PMMA in any given experimental conditions.