Thermal and mechanical properties of stereocomplex polylactide enhanced by nanosilica

Stereocomplexable polylactide (sc-PLA) with improved thermomechanical performance had been prepared by melt compounding of poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and nanosilica. The silica nanoparticles dispersed evenly in the sc-PLA matrix and there were no air bubbles because of good compatibility between nanosilica and sc-PLA. The aggregates size of nanosilica increased with increasing nanosilica content. The introduction of nanosilica facilitated the formation of stereocomplex, which was manifested as the degree of crystallinity of sc-PLA increased from 17.0 to 24.3% as the nanosilica content increased from 0 to 10 wt%. Thermal stability of sc-PLA was greatly improved by adding nanosilica, and the onset of decomposition temperature of sc-PLA/silica nanocomposites was ~33 °C higher than that of neat sc-PLA. Superior storage modulus was found for sc-PLA/silica nanocomposites compared to neat sc-PLA. The tensile strength and modulus of sc-PLA nanocomposites were greatly improved by the addition of nanosilica, but the elongation at break decreased.