Influence of nanoclays on the photochemical behaviour of poly(vinyl alcohol)

The photochemical behaviour of poly(vinyl alcohol)/clay nanocomposite films with a natural Montmorillonite clay (MMt-Na+) and a synthetic Laponite clay at varying concentrations (up to 10 wt%) was investigated. Nanocomposite films were exposed to UV-visible light irradiation (lambda > 300 nm) in accelerated ageing conditions in both the presence and absence of oxygen. Under photo-oxidation conditions, the same photoproducts of PVA were formed in the presence of both clays, but a discrepancy in the photo-oxidation rate of PVA was observed for the different clays. MMt-Na+ displays a pro-degradant effect that was influenced by the clay content, whereas Laponite has no influence on the oxidation rate of PVA. However, in the absence of oxygen, both PVA/clay nanocomposites proved to be as photostable as PVA. (C) 2012 Elsevier Ltd. All rights reserved.