Some fundamental aspects of the photooxidation and stabilisation of polymers

Hydroperoxides are believed to be the species primarily responsible for initiation and chain scission during the early stages of the photooxidation of polymers. Derived carbonyl compounds undergo photolysis during the later stages. Photoantioxidants are now known to act either by removing chain-propagating species, in some instances by a catalytic mechanism, or by interfering with the initiation step in a non-radical process. Photoantioxidants are distinguished from thermal antioxidants by their much greater stability to ultraviolet light, but peroxidolytic antioxidants with limited light stability have been found to have practical utility as time-controlled photoantioxidants for polyolefins.