Accelerated photo-oxidation of polyethylene. II. Further evaluation of selected additives

A number of additives previously observed to promote photo‐oxidative degradation of polyethylene films have been evaluated with respect to their relative photoinitiating effectiveness at wavelengths near 300 nm and their effects on thermal‐oxidative stability of polyethylene. Depending on the nature of the additive, the photo‐oxidation process may display autoretarding or autoaccelerating behavior. Thermomechanical analyses and gel content measurements on UV‐exposed films containing substituted anthraquinones suggest that at short exposure times, photo‐oxidative degradation is accompanied by photochemical crosslinking.