Effect of the molecular weight of poly(vinyl acetate) on the polymorphism and thermomechanical properties of poly(L-lactic acid)/poly(D-lactic acid) blends

The effects of molecular weight ( M w ) and content of poly(vinyl acetate) (PVAc) on the crystallization behaviors, competing crystallization of homocrystallites and stereocomplex crystallites (SCs), crystalline structure, and mechanical properties of poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA) blends were investigated. The crystallization of PLLA/PDLA component is accelerated after the addition of low-M w PVAc and is suppressed with high-M w PVAc. The ability of SC formation is enhanced via blending with PVAc, irrespective of its M w , and becomes prominent with low-M w PVAc. The exclusive SCs are obtained in the blends with 30 mass % low-M w PVAc. The improvement in thermomechanical property above 170 °C is ascribed to the enhancement of SC content. This work presents guidance for achieving the melt processability of SC-PLA, thus proving their potential as a high-performance substitute for conventional plastics.