Stereocomplex Crystallization and Spherulite Growth of Low Molecular Weight Poly(L-lactide) and Poly(D-lactide) from the Melt

In isothermal crystallization from the melt, only stereocomplex crystallites as a crystalline species were formed in all the blends at crystallization temperature above 130 °C. The spherulite growth rate and crystallinity values decreased monotonically with deviation of the PDLA content from 50%. Surprisingly, regime analysis revealed that the crystallization mechanism of the blends was independent of PDLA content. In non‐isothermal crystallization of melt‐quenched specimens during heating, the cold crystallization of blends takes place rapidly at a lower temperature compared to that of pure PLLA and PDLA. This is attributable to the rapid stereocomplex crystallization or the nucleating effect of stereocomplex crystallites formed during quenching from the melt or second heating. The stereocomplex spherulites of blends from low molecular weight Poly(L‐lactide) (PLLA) and Poly(D‐lactide) (PDLA) at around a PDLA content of 50% had a much higher maximum spherulite growth rate compared to those of pure PLLA and PDLA. On the basis of regime analysis, the stereocomplex crystallization mechanism in the blends remained unchanged, irrespective of PDLA content, in the crystallization temperature range above 130 °C.