Peroxide enhancement of poly(alpha-methylstyrene) thermal degradation

An experimental study showed the enhancement effect of di-tert-butyl peroxi de on poly(alpha -methylstyrene) (PAMS) thermal degradation in trichloroben zene solution (12.5 g/L). Peroxide was continuously injected into the react ing polymer solution at low flow rates (0.3-4.0 mL/h). Samples were taken p eriodically and analyzed by GPC to determine the temporal behavior of the m olecular weight distribution. Peroxide addition fundamentally altered the d egradation mechanism to one in which random degradation was significant. A distribution kinetics model based on the fundamental free-radical processes of initiation - termination, beta -scission, and hydrogen abstraction was developed to describe the irreversible polymer degradation process. Reactio n rate coefficients that are linearly dependent on the polymer molecular we ight are the model parameters fitted to experimental data. The Arrhenius ac tivation energies for individual steps in the reaction mechanism were calcu lated on the basis of the temperature dependence of the reaction rate. The different mechanisms for peroxide-enhanced thermolysis of PAMS and polystyr ene are clarified by the distribution kinetics approach.