Poly(lactic acid)/Titanium Dioxide Nanocomposite Films: Influence of Processing Procedure on Dispersion of Titanium Dioxide and Photocatalytic Activity

摘要

Poly(lactic acid)/titanium dioxide (TiO2) composite films were prepared by direct melt processing using three different procedures (i.e., compression molding, twin-screw melt extrusion, and melt extrusion and ther-moforming). The effect of TiO2 loading and processing procedures on the phase morphology and on the thermal, mechanical, and barrier properties of the obtained nanocomposites were analyzed respectively by field-emission scanning electron microscopy-energy dispersive spectrometry, differential scanning calorime-try, universal testing machine, and water vapor and oxygen permeability measurements. The incorporation of TiO2 nanoparticles into the poly(lactic acid) matrix increased the crystallinity and improved the barrier properties of the composites. The maximum tensile strength was achieved at the 2% content of TiO2 for the films produced by compression molding and twin-screw melt extrusion, whereas the tensile strength for films produced by melt extrusion and thermoforming decreases markedly with an increasing TiO2 content. The photocatalytic activities of the obtained nanocomposites were investigated by analyzing the degradation of methyl orange. Results confirmed that the processing procedures and the distribution of TiO2 in the polymer matrix are the key parameters, which rule the photocatalytic behavior of composite films.