Radiolytic degradation and stabilization of poly(vinyl chloride)

Medical products, food packaging and pharmaceutical products all made with poly(vinyl chloride) (PVC) can suffer degradation when they go through sterilization by gamma radiation. stabilizing additives are used to minimize the degradation of this polymer. There additives act by substituting irregular structures such as the allylic chloride atom in the PVC by stable structures, thus retarding the radiolytic degradation of the polymer. In this study we looked at the radiolytic degradation in films of PVC plasticised with DEHP and stabilized with Tinuvin P, by viscometry, mechanical properties and ultraviolet-visible absorption spectroscopy. The variation of the number of scissions per chain, studied by viscometry showed efficiency in the stabilized polymer. The results showed an excellent protection of scission degradation of the chain attributed to the stabilizer, with a maximum protection of 90% at a concentration of 0.5% Tinuvin P, as well as the improvement of the mechanical properties when the polymer is subjected to different doses of radiation. (C) 2003 Elsevier Ltd. All rights reserved.