Photocatalyzed Degradation of Polymers in Aqueous Semiconductor Suspensions. 3. Photooxidation of a Solid Polymer: TiO2-Blended Poly(vinyl chloride) Film
The photooxidative degradation of a TiO2-blended poly(vinyl chloride) (PVC) film and other PVC specimens was carried out under UV light and under solar exposure to test the feasibility that such polymeric materials can be mineralized. The effects of the degree of polymerization and the presence of a plasticizer (o-dioctyl phthalate; DOP) in the PVC on the photooxidation process were examined by scanning electron microscopy (SEM), by X-ray photoelectron spectroscopy (XPS), by gel permeation chromatography, and by gas chromatography for CO2 evolution. The TiO2-blended PVC thin film is more easily decomposed than PVC particles (or film) alone in a TiO2 particulate dispersion. The collapse phenomena of polymeric films are closely dependent on the photodegradation rate of DOP in the PVC film. Ames mutagenic assays for the photodegraded solution in aqueous TiO2/PVC dispersions showed a slight mutagenic activity in TA98 without S9 mix for products formed during the photodegradative oxidation.