Preparation of stereocomplex polylactic acid fiber and evolution of crystal structures

Stereocomplex polylactic acid (ScPLA) fibers were successfully prepared by mixing equal mass melts of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) by melt spinning process. The evolution of crystal structures of ScPLA fibers was investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results show that the homogeneous crystal (Hc) will be converted to stereocomplex crystal (Sc) as the heat setting temperature (HT) increases. The crystallinity curves of Hc and Sc cross into an “X” and the cross point is near the melting point of the Hc. The temperature range to form ScPLA fiber with fully stereoscomplex structures is 187 ℃ to 197 ℃ and the maximum Sc content is about 60%.