Influence of chain extender on thermal properties and melt flow index of stereocomplex PLA

The effects of chain extension and melt blending temperature on the stereocomplex formation of 50/50 (w/w) poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA) blends or stereocomplex polylactides (scPLAs) were investigated. Joncryl (R) ADR 4368, a styrene-acrylic multifunctional oligomeric agent, was used as a chain extender. Differential scanning calorimetry and X-ray diffractometry were used to confirm the stereocomplex formation of the PLLA/PDLA blends. Melt flow indices (MFI) of the blends were also determined. The stereocomplex crystallinities gradually decreased with increasing blending temperature and Joncryl (R) ADR 4368 ratio. The significant decrease in the MFI of scPLAs is believed to be attributed to chain extension at the blending temperatures of 170 degrees C and 200 degrees C. The MFI values of scPLAs decreased as the Joncryl (R) ADR 4368 ratio and blending temperature increased. The results indicated that the chain extension has an effect on the stereocomplexation and it improved the melt strength of the scPLAs. (C) 2015 Published by Elsevier Ltd.