A study of the photodegradation of polyvinyl chloride

Abstract

Mass spectrometry has been used to examine the photoinduced dehydrochlorination of polyvinyl chloride films both in the absence and presence of titanium dioxide. Hydrogen chloride evolution was only observable when light of λ < 300 nm was used. The presence of titanium dioxide affords some protection. When light of λ > 300 nm is used photodegradation of added stabilisers is observed. Preliminary experiments indicate that rigid polyvinyl chloride behaves in a similar way to the film. By use of infra-red spectroscopy it was shown that polyvinyl chloride photodegrades in the presence of air to give carbonyl compounds, hydroperoxides and polyenes if light having λ < 300 nm is used. Added titanium dioxide can retard these processes. From these results and those obtained with light of λ > 300 nm, in which only carbonyl compound formation can be observed, it is proposed that the routes for carbonyl compound and hydroperoxide formation are not necessarily inter-related.