| Abstract: | This paper reexamines the role of transition metal salts (mainly CuCl2 and FeCl3) in the photooxidative degradation of polymers. Metal salts belong to external impurities originated in polymers from synthesis, processing, storage, contacts with metal corrosion, etching reactions, etc. Transition metal salts in the presence of water become very reactive species. In such metal chlorides as CuCl2 and FeCl3 UV and/or visible light irradiation causes an electron-transfer from Cl? to metal cation. The produced chlorine radical can abstract hydrogen atom from a polymer molecule giving polymer alkyl radical. which is easily oxidized in air. This process is accompanied with a chain scission reaction which is responsible for the degradation of a polymer. Mechanisms of these reactions are discussed in detail. |
