Effect of UV-irradiation on poly(vinyl chloride) modified by methyl methacrylate-butadiene-styrene copolymer

The influence of methyl methacrylate-butadiene-styrene copolymer (MBS) on poly(vinyl chloride) (PVC) photodehydrochlorination and photooxidative degradation was investigated by UV-vis, FTIR and fluorescence spectra. The gel amount formed in exposed samples was estimated gravimetrically. It was found that MBS decelerates PVC photodehydrochlorination and photocrosslinking; the effect is caused by the fact that the Cl radicals react with H atoms at tertiary atoms in polystyrene of MBS and initiate the depolymerisation of the PMMA chains of MBS, then leads to reinitiation of PVC dehydrochlorination. The surface free energy of PVC/MBS blends was calculated on the basis of contact angle measurements. The rate of photocrosslinking and photodegradation distinctly influenced the surface free energy, which can reach a maximum value at an appropriate irradiation time.