The rheological and mechanical properties of biodegradable poly(lactic acid)/poly(butylene succinate-co-adipate) blends

Poly(lactic acid) (PLA) was blended with poly(butylenesuccinate-co-adipate)(PBSA) with hexamethylenediisocyanate (HDI) in a torque rheometer. Blend ratios of 80/20, 70/30, 50/50, 30/70, and 20/80 PLA/PBSA blends were prepared. There was a large difference in melt viscosity between PLA and PBSA, which led to mixing difficulty. The PBSA reacted with HDI (0.15wt%, 0.23wt%, and 0.35wt%) to increase of the melt viscosity of PBSA before blending with PLA. The purpose was to study the effects of HDI on compatibility, rheological, mechanical, thermal, morphological and hydrolytic degradation properties of PLA/PBSA blends. Test samples were prepared through the compression molding process.; The molecular weight of PBSA increased with increasing of HDI content based on Gel Permeation Chromatography (GPC) data. However, the glass transition temperature of PBSA containing HDI was similar to that of pure PBSA. The melt viscosity of PBSA also increased with the increasing of HDI content at various temperatures. The hydrolytic degradation of pure PBSA was faster than that of modified PBSA.; Differential Scanning Calorimeter (DSC) analysis indicated that PLA/PBSA reacted with the HDI blends has two Tg's of PLA and PBSA reacted with HDI, demonstrating the immiscibility of the blends. The tensile properties of PLA/PBSA reacted with the HDI blends were improved over those of PLA/pure PBSA blends.