Kinetics of thermooxidation and photooxidation of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene), 2. A suggestion of the reaction mechanism

A basic kinetic scheme for the thermo‐ and photodegradation of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) ( 1 ) is suggested on the basis of a comparison of theoretically possible reactions and the experimental results described in a previous work. Various possibilities of initiation are discussed (direct oxidation, thermal, catalytic, or photochemical decomposition of the hydroperoxy groups). The decomposition of hydroperoxy groups is considered to be the most important initiation reaction. The kinetic chain length of thermooxidation is very close to unity; the major reaction products (containing alcohol and aldehyde groups) are probably formed through the termination process. The relationship deriving from the kinetic scheme indicates the second reaction order in [ 1 ], which was experimentally found in mixtures of 1 with polystyrene. In the case of photooxidation the dominant role is played by quinone structures as photosensitizers. The routes leading to the formation of alcohol, ester, and aldehyde groups as the most significant oxidation products are discussed.