Melt processed PLA/PCL blends: Effect of processing method on phase structure, morphology, and mechanical properties

Poly(lactic acid) (PLA)-rich poly(lactic acid)/poly(epsilon-caprolactone) (PLA/PCL) blends were melt-blended at different compositions. The compositions such as 90/10 and 80/20 were obtained using three different blending methods and processed by injection molding and hot pressing. All blends were immiscible. The crystallinity of PLA increased slightly in the presence of poly(epsilon-caprolactone) (PCL), and the PCL exhibited fractionated crystallization in the presence of PLA. Injection molded specimens, compared with hot pressed specimens, presented much smaller PCL particles regardless of the blending method used. Some interfacial adhesion was observed in all cases. The stiffness of PLA/PCL blends decreased as the PCL content was increased and was independent of processing. Injection molded specimens showed ductile behavior and broke at elongation values close to 140%, while the elongation at break of the hot pressed specimens was clearly lower, most likely due to the larger size of the PCL particles. Although the impact strength of the blends remained low, it improved by approximately 200% with 30% PCL and by 350% with 40% PCL. (C) 2015 Wiley Periodicals, Inc.