Entanglement Effect on Chain-Folding Structure in Semicrystalline Polymer Blends

Entanglement effect on chain-folding structure of semicrystalline polymers is not clearly understood over the past decades. Very recently, we demonstrated that Poly(Lactic Acids) chains with three different molecular weights of 46K, 90K, and 320K g/mol do not change adjacent re-entry structure under different supercoolings. It was suggested that entanglement of polymer chains limit adjacent re-entry number in the melt-grown crystals. In this study, we isothermally crystallize polymer blend samples consisting of long and short Poly(Lactic acid) chains from the melt state. Only long polymer chains are labeled by ¹³C. ¹³C-¹³C double quantum (DQ) spectroscopy is applying to study local chain-folding structure of PLLA as a function of blending ratio and as a function of molecular weight of short PLLA chains.