The decomposition of benzoyl peroxide in polystyrene

The rate of decomposition of benzoyl peroxide in polystyrene has been measured at 70.9, 80.1, and 89.5°C. The kinetics are strictly first order. There is no dependence of rate on concentration, which indicates that radical‐induced decomposition is absent. At 70–80°C., the Arrhenius relationship is k = 1.39 × 1017e−35,700/RT and at 80–90°C., k = 2.67 × 1013e−29700/RT. Above 80°C., the apparent second‐order transition temperature of polystyrene, the rates of decomposition correspond fairly closely to the rates of spontaneous decomposition of benzoyl peroxide in benzene. Below 80°C., the rates of decomposition of benzoyl peroxide in polystyrene are considerably smaller than those in benzene. Two possible explanations of this behavior are presented.