Photodegradation of poly(vinyl chloride‐ co‐vinyl acetate)


The induced photodegradation of poly (vinyl chloride-co-vinylacetate) films in air was investigated in solid state in the absence andpresence of aromatic carbonyl compounds (photosensitizers) such asl,4-naphthaquinone (NQ) and benzophenone (BPH) 'The photodegradation rate was studied using u.v.-radiation at l" = 313nm , intensity 3.49*10-s at temperature 45 oC andfollowed by U.V.-Vis. and I'R spectrophotometry using acceleratedweathering testerThe addition of (0.2vo w/w) of low molecular weight aromatic carbonylcompounds photosensitizers to copolymer films (25pm in thickness)enhanced the photodegradation of the copolymer' Thephotodegradation rate was measured by the increase in hydroxylabsorbance (LR spectrophotometry) and photodegradation rate constant(ka) . According to the kinetic data and other experimental results theinduced photodegradation mechanisms of copolymer films weresuggested under the experimental conditions employed'The rate of photodegradation of copolymers increases withbenzophenone (BPH) and 1,4-naphthaquinone (NQ) asphotosensitizers conc. The increase in the rate of photodegradation ishigher with 1,4-naphthaquinone (NQ)'