Morphology and thermal degradation studies of melt-mixed PLA/PHBV biodegradable polymer blend nanocomposites with TiO2 as filler.

Abstract

The morphology and thermal stability of melt-mixed poly(lactic acid) (PLA)/poly(hydroxybutyrate-co-valerate) (PHBV) blends and nanocomposites with small amounts of TiO2 nanoparticles were investigated. PLA/PHBV at 50/50 w/w formed a cocontinuous structure, and most of the TiO2 nanoparticles were well dispersed in the PLA phase and on the interface between PLA and PHBV, with a small number of large agglomerates in the PHBV phase. Thermogravimetric analysis (TGA) and TGA–Fourier transform infrared spectroscopy was used to study the thermal stability and degradation behavior of the two polymers, their blends, and nanocomposites. The thermal stability of PHBV was improved through blending with PLA, whereas that of the PLA was reduced through blending with PHBV, and the presence of TiO2 nanoparticles seemingly improved the thermal stability of both polymers in the blend. However, the degradation kinetics results revealed that the nanoparticles could catalyze the degradation process and/or retard the volatilization of the degradation products, depending on their localization and their interaction with the polymer in question.