Laser-induced degradation of polyvinyl chloride II: Oxygen bleaching of polyenes

Abstract The reaction of oxygen with polyenes of polyvinyl chloride was shown to proceed effectively under irradiation by the 514.5 nm emission line of an argon ion laser. The quantum yield of this photobleaching was estimated to be 0.015. A mechanism is suggested for the oxygen bleaching reaction both in the dark and under laser irradiation. The polyenyl radicals (CHCH) n HCH 2 CHCl, resulting from chlorine β-scission of excited singlet polyenes, are assumed to play a predominant role by reacting with 3 O 2 to form allylic hydroperoxides or cyclic peroxides by an intramolecular process.