LAUSR

Poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) with various molecular weights (MW) were melt blended in equivalent proportions, and then followed by injection molding to form polylactide stereocomplex (sc-PLA). The crystalline structures, thermal resistance, and mechanical properties of the formed sc-PLA were then investigated in detail. The results showed stereocomplex crystallites (sc) were formed predominantly in all the sc-PLA regardless of the MW of the PLLA or PDLA pellets, and a small amount of homocrystallites (hc) also coexisted in sc-PLA. The MW of PLLA and PDLA pellets displayed significant effects on the crystallinity, thermal resistance, and mechanical properties of sc-PLA. PLLA and PDLA with low and similar MW facilitated the formation of sc, and also improved the onset degradation temperature and Vicat softening temperature of sc-PLA. For a similar degree of crystallinity, high MW was found to be more favorable in improving the thermal performance of sc-PLA. Although sc-PLA prepared from PLLA and PDLA with low MW showed decreased mechanical properties, the mechanical properties of sc-PLA increased with an increase in the MW of the PLLA or PDLA pellet. When PLLA and PDLA pellets with high and similar MW were used, the mechanical properties of sc-PLA could even exceed those of pure PLLA.