The kinetics and mechanisms of the thermal degradation of poly(methyl methacrylate) studied by thermal analysis-Fourier transform infrared spectroscopy

The kinetics and mechanisms of thermal degradation of poly(methyl methacryl ate) (PMMA) have been studied to demonstrate the usefulness of thermal anal ysis-Fourier transform infrared spectroscopy (TA-FTIR) as a qualitative and quantitative kinetic tool to study the thermal degradation of polymers. Fr om the dependence of the rate of thermal degradation of PMMA on molecular w eight at low degradation temperatures, it was concluded that thermal degrad ation was initiated by a mixture of chain end and random chain scission ini tiation, followed by depropagation and first-order termination. Random scis sion is attributed to pre-oxidation of the polymer on storage at room tempe rature. At higher temperatures, a change in molecular weight dependence was observed, related to depropagation to the end of the polymer chain. The th ermal degradation of PMMA also leads to the production of char, which was p roduced by the elimination of methoxycarbonyI side-chains. The amount of ch ar produced increased with increasing concentration of end-groups and tempe rature. (C) 2001 Elsevier Science Ltd. All rights reserved.