Accelerated Photodegradation of Solid Phase Polystyrene by Nano TiO2-Graphene Oxide Composite under Ultraviolet radiation

Abstract

Nano TiO2-graphene oxide (TiO2-GO) composites with varying weight percentages of GO were successfully developed by ultrasonication assisted hydrothermal approach and characterised. HRTEM analysis revealed that the GO sheets associated with TiO2 have broken down into nano dimensions. Photodegradation of polystyrene (PS), PS-TiO2 and PS-TiO2-GO composites were studied under UV irradiation of wavelength 253 nm. Nano TiO2-GO loaded solid phase polystyrene (PS) underwent an accelerated photodegradation compared to Pristine PS and PS-TiO2 composite as evident from various monitoring techniques. Gel permeation chromatography (GPC) revealed that the degradation proceeded through random chain scissions decreasing the average molecular weights. PS and PS composites followed the mechanism of photo oxidative degradation as evident from FTIR. Maximum degradation percentage was observed in PS-TiO2-30%GO compared to the other specimens under study. Mechanical properties including tensile and flexural strengths which were found to be higher for the PS composites compared to pristine PS, decreased appreciably upon UV irradiation due to deterioration of polymer chain. Dielectric strength of the PS composites also decreased as a consequence of photodegradation revealing the formation of charge centers within the polymer chain. Dielectric permittivity of the polymer specimens under study increased upon UV irradiation suggesting the formation of more polar centers. The improved thermal stability of PS composites compared to pristine PS decreased due to photodegradation of the polymer chain. The glass transition temperature (Tg) and decomposition temperature lowered as a consequence of chain scission of polymer specimens caused by photodegradation. Photocatalytic activity of nano TiO2 was enhanced upon its surface modification using GO for the photodegradation of PS under UV radiation.