Titanium dioxide microspheres modified with cobalt stearate as a photocatalyst for the degradation of polyethylene films

Abstract

The degradation of plastics is of great importance due to the ever-increasing concerns of environmental issues. Herein, we report a photocatalyst for the degradation of polyethylene (PE) films, that is, nano titanium dioxide (TiO2) nanoparticles modified with cobalt stearate, which was prepared by sol-gel method and surface modification. Its structure, morphology, and thermal stability were studied by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Then the prepared photocatalyst was added to the linear low-density polyethylene (LLDPE) resin, resulting in a novel PE/TiO2 composite film. The effects of the modified TiO2 on the plasticity of PE film and the degradation performance of the composite film under UV irradiation were investigated. The mechanical properties, molecular weight change, and melting index (MFR) of the film were measured. The results revealed that the degradation properties of PE films were significantly improved after the addition of modified nano TiO2 microspheres. Under UV irradiation for 96 h, the tensile elongation retention rate of the composite film dropped to 0. The peak at 1713 cm-1 attributable to the stretching vibration of CO in infrared spectra significantly increased and the weight-average molecular weight (Mw) of the film decreased from 1.2 × 105 g mol-1 to 0.85 × 104 g mol-1. The melt flow rate was enhanced to 194.2 g/10 min. These results suggest that the present modified TiO2 could be utilized as a promising photocatalyst candidate for the degradation of plastics.