Study of the interfacial chemistry of poly(vinyl chloride) paint on steel exposed to the ultraviolet-water condensation test

摘要

The effect of exposure to the UVCON (humidity and UV radiation) accelerated corrosion test of a poly(vinyl chloride) paint applied over cleaned, abraded, and pre-rusted mild steel substrates has been investigated from the interfacial chemistry and adhesion standpoints. The X-ray photoelectron spectroscopy (XPS) data reveal significant differences in the locus and mode of adhesion loss, which depend on the time of exposure and the initial presence of a rust layer on the mild steel. The adhesion values obtained with the pre-rusted mild steel were greater than those obtained with the cleaned and abraded mild steel before exposure. After 15 days of exposure, it was observed that changes in the interfacial surface composition of the PVC/cleaned and abraded mild steel systems might have important positive effects on the adhesion strength values. The XPS data suggest the oxidation of both interfacial surfaces incorporating polar C-O and C=O species, which would be expected to enhance the adhesion of paint to metal. In contrast, the PVC paint/pre-rusted mild steel system showed no change in adhesion values or interfacial surface composition over the entire period of exposure.