Characterization of biodegradable polymers by inverse gas chromatography. III. Blends of amylopectin and poly(L -lactide)

摘要

The morphology changes and surface thermodynamics of blends of amylopectin (AP)-poly(L-lactide) (PLA) were investigated over a wide range of temperatures and compositions using the inverse gas chromatography method. Twenty-five solutes were selected such as alkanes, acetates, oxy, halogenated, and six-member ring families. They provided a variety of specific interactions with the blends' surface. The morphology showed two regions, some others showed a de-polymerization above 130°C. These zones enabled the estimation of T _g and T_m of AP, PLA, and the blends. Blending AP with PLA caused a decrease in AP's T_g value due to the reduction of the degree of crystallinity of the blend. Exothermic values of Ξ_(23) were obtained indicating the compatibility of AP and PLA at all temperatures and weight fractions of AP-PLA. The miscibility was favored at 75%AP, only 25%AP-75%PLA composition influenced the degree of crystallinity. The dispersive component of the surface energy of the blends ranged from 16.09 mJ/m~2 for the pure AP as high as 58.36 mJ/m~2 at 110°C when AP was mixed with PLA in a 50-50% ratio. The surface energy was at its highest value when the composition was 75% of AP, in good agreement with Ξ_(23) values.