Controlling stereocomplexation, heat resistance and mechanical properties of stereocomplex polylactide films by using mixtures of low and high molecular weight poly(D-lactide)s
AbstractStereocomplex polylactide (scPLA) films were prepared by blending poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) solutions before solvent evaporation. The PLLA/PDLA ratios were 80/20 and 60/40 (w/w). PDLAs with low and high molecular weights (M.W.) were used as PDLA mixtures. The scPLA films with different low/high M.W. PDLA ratios were investigated for both the 80/20 and 60/40 (w/w) scPLA film series. Stereocomplexation, heat resistance and the mechanical properties of the scPLA films were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing, respectively. The results indicated that low M.W. PDLA can enhance the stereocomplexation and heat resistance of scPLA films while the high M.W. PDLA can improve tensile properties of scPLA films. It was concluded that the stereocomplexation, heat resistance and tensile properties of scPLA films could be controlled by adjusting the low/high M.W. PDLA ratio in PDLA fraction.