Effect of Chain extender on morphology and tensile properties of poly(L-lactic acid)/poly(butylene succinate-co-L-lactate) blends

Abstract The effect of a multi-functional epoxy-based chain extender on the tensile properties of poly( l -lactic acid) (PLLA)/poly(butylene succinate-co- l -lactate) (PBSL) blends was investigated using X-ray diffraction, differential scanning calorimetry, attenuated total reflection infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The PLLA/PBSL blend without the chain extender showed low strain at break because of its immiscible sea-island morphology. The chain extender reacted with both PLLA and PBSL during the blending process to produce three types of graft polymers. The graft polymer formed by the reaction of the chain extender with both PLLA and PBSL at the PLLA/PBSL interface improved the miscibility and tensile properties of the blend through interfacial interactions. The graft polymers connected with either PLLA or PBSL existed within the PLLA or PBSL domains, respectively and suppressed the molecular motions due to the intra-domain interactions. When 4 % chain extender was used, the miscibility of the blend improved and the suppressed molecular motions of the PBSL portion increased the maximum stress and strain at break. At the chain extender concentration of 6 %, the miscibility of the blends did not increase; however, the interfacial and intra-domain interactions increased, which deteriorated the tensile properties of the blends.