Abstract
The influence of small amount of poly(vinyl acetate) (PVAC) on poly(vinyl chloride) (PVC) photooxidative degradation was investigated by FTIR, UV–Vis and solid state 13 C -NMR spectroscopy. The gel amount formed in exposed samples was estimated gravimetrically. Moreover, surface free energy of PVC+PVAC films was calculated on the base of contact angle measurements. It was found that PVAC decelerates PVC photodegradation, photocrosslinking and photooxidation leading to carbonyl groups formation. This effect is caused by an efficient quenching of macroradicals by low radicals formed in primary photochemical reactions in both polymeric phases. UV-irradiation leads to significant changes of surface properties in all samples studied. In most cases surface free energy decreases with irradiation time but it is caused by an efficient drop of its dispersive component whereas polar component markedly increases due to the formation of functional groups. The mechanism of observed photochemical processes including interactions between both components has been discussed. The influence of sample morphology on the course of photochemical reaction and protection effect induced by carbonyl groups from PVAC was also suggested.
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