Enhanced toughness and strength of poly (d-lactide) by stereocomplexation with 5-arm poly (l-lactide)

摘要

The enhancement of mechanical properties were achieved by solution blending of poly(d-lactide) (PDLA) and 5-arm poly(l-lactide) (5-arm PLLA). Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) results indicated almost complete stereocomplex could be obtained when 5-arm PLLA exceeded 30wt %. Tensile test results showed that the addition of 5-arm PLLA in linear PDLA gave dramatically improvement both on tensile strength and elongation at break, which generally could not be increased simultaneously. Furthermore, this work transformed PDLA from brittle polymer into tough and flexible materials. The mechanism was proposed based on the TEM results: the stereocomplex crystallites formed during solvent evaporation on the blends were small enough (100-200 nm), which played the role of physical crosslinking points and increased the interaction strength between PDLA and 5-arm PLLA molecules, giving the blends high tensile strength and elongation at break. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42857.