Solid-phase photocatalytic degradation of PVC-TiO2 polymer composites

Abstract

The solid-phase photocatalytic degradation of poly(vinyl chloride) (PVC)-TiO2 composite films was investigated under the ambient air in order to assess the feasibility of developing photodegradable polymers. The photodegradation of the composite films was compared with that of pure PVC films through performing weight loss monitoring, scanning electron microscopic (SEM) analysis, gel permeation chromatography (GPC), FT-IR and UV-VIS spectroscopy, and X-ray photoelectron spectroscopy (XPS). TiO2-embedded PVC showed highly enhanced photodegradation. Irradiating the composite film for 300 h under air reduced its average molecular weight by two-thirds and weight by 27% while the irradiation under nitrogen atmosphere induced little degradation. The photocatalytic degradation of the composite film accompanied the increase in the FT-IR carbonyl peak intensity, the evolution of CO2 and H2O, and the whitening due to the visible light scattering from growing cavities. XPS analysis of the composite film showed that the surface concentration of oxygen increased while that of chlorine decreased with irradiation. The SEM images of the irradiated composite films showed the development of cavities around the imbedded TiO2 particles and implied that active oxygen species which were photogenerated on TiO2 surface desorb and diffuse across a few micrometers to react with the polymer matrix. (C) 2001 Elsevier Science B.V. All rights reserved.