Characteristic features of solid-phase photooxidation of isotactic polypropylene and the efficiency of photoinitiators

Abstract

The rate of decay of macroperoxy radicals PO 2 formed in polypropylene by photoinitiated transformations of various initiators has been measured under conditions of long reaction chains of oxidation. New effects specific for oxidation proceeding in the solid phase have been found: the dependence of the rate constants characteristic for second-order decay of PO 2 on the irradiation time, on initial concentration of radicals, and on their mutual distance. A new kinetic law of radical decay, generally valid for various initiators, has been established such that the chain termination does not follow the second-order mechanism. The results are interpreted as stemming from non-uniformity of reaction rate in the solid polymer.