Polymer oxidation and secondary cage combination of peroxyl radicals

Abstract

Abstract The photo‐oxidation of solid polymers at ambient temperatures is shown to be greatly affected by the low mobility of radicals in the solid state. When a radical pair, produced by photo‐initiation, escapes the initial polymer cage, the probability of its recombination remains high even after several propagation steps. This phenomenon, known as secondary cage recombination, has a pronounced effect on the kinetics of oxidation and on the mechanism of photostabilisation by radical scavengers. The occurrence of secondary cage recombination is demonstrated for polypropylene photo‐oxidation and a kinetic analysis is developed to predict the consequences of this effect.