Thermal degradation of poly(methyl methacrylate) in a closed system

The thermal degradation of poly(methyl methacrylate) has been studied with unfractionated and fractionated polymer samples over a temperature range of 275–400°C. in a closed system by a new technique. Kinetic data have been obtained at temperatures about 100°C. higher than was possible previously. The results are compared with those obtained in open systems. Two main degradation reactions are operative. It is shown that the energies of activation for these reactions do not vary with polymer chain length in accordance with what is to be expected from the usually assumed depolymerization mechanisms. The termination reactions are diffusion‐controlled. Hydrogenation by Adam's catalyst and bromination of the polymers have only moderate effects on the rate of degradation.