Photocatalytic Oxidative Degradation of Poly(alkyl acrylates) with NanoTiO2

Abstract

The degradation of poly(alkyl acrylates) was investigated in the presence of two catalysts: commercial Degussa P-25 and TiO2 synthesized by combustion synthesis (CS-TiO2). The molecular weight distributions of the polymers were measured by gel permeation chromatography. The effect of alkyl group substituents on the photodegradation of poly(alkyl acrylates) was investigated. The degradation rate of poly(alkyl acrylates) decreased with increase in the number of carbon atoms of the alkyl substituents, and the degradation of the polymers in the presence of CS-TiO2 was significantly higher than that obtained with Degussa P-25. The effect of oxidizer on the UV-assisted oxidative degradation kinetics of poly(ethyl acrylate) was studied. The degradation was also investigated at various temperatures without UV, and enhancement in the oxidative degradation rate under UV exposure was observed compared to that under thermal conditions. Theoretical models for the degradation in the presence and absence of oxidizers using continuous distribution kinetics were developed to determine the kinetic parameters. The hydrogen abstraction and oxidative random chain scission rate coefficients were found to be independent of the oxidizer and were dependent only on the polymer. The overall polymer degradation rate in the presence of different oxidizers was predicted without any adjustable parameters.