SURFACE-ANALYSIS AND PEEL STRENGTH OF AGED, OXYGEN-PLASMA-MODIFIED UNPLASTICIZED POLY(VINYL CHLORIDE) FILMS

The surface of unplasticized poly(vinyl chloride) (UPVC) was modified by oxygen plasma treatment and analysed using X-ray photoelectron spectroscopy (XPS), contact angle analysis (CAA) and 180 degrees peel test measurements. XPS results show a surface rich in oxygen-containing species which are detectable on the surface after 10 weeks following plasma treatment. CAA results, however, indicate that an initial increase in surface energy immediately after the plasma treatment is followed by a dramatic decrease after 24h of ageing due to a thin layer of organic contamination. Peel test results imply that oxygen plasma treatment initially increases peel strength of Scotch Magic (R) tape against the surface, but after 8 weeks the peel strength decreases below that of the untreated sample, suggesting the formation of a weak boundary layer.