Accelerated crystallization of high molar mass poly(L/D-lactic acid) by blending with low molar mass poly(L-lactic acid)

作者：Di Lorenzo Maria Laura^*; Androsch Rene

来源：European Polymer Journal, 2018, 100: 172-177.

DOI：10.1016/j.eurpolymj.2018.01.030

• Blends
• Crystallization kinetics
• PLLA
• Crystal growth rate

The crystallization kinetics of poly(L/D-lactic acid) (PLLA) with a molar mass of around 120 kDa and containing 4% of D-isomers is sizably improved by blending with low amount (< 10 m%) of a PLLA of high stereoregularity, made of pure L-isomer, and molar mass of 4 kDa. Blends of the two PLLA's are prepared by solution mixing. The blends are homogeneous in the melt and display a single, composition-dependent glass transition. Increasing concentration of the highly stereo-regular low-molar mass component in the blends results in an earlier onset of crystallization and a higher crystal growth rate. The blend composition affects the crystal polymorphism of PLLA, as increasing content of the highly stereoregular and low molar mass polymer favors growth of alpha-crystals at lower temperatures than typically observed in unmodified PLLA. It is suggested that the short PLLA molecules of the low-molar mass component start to crystallize at higher temperature than the long molecules of the high molar mass component, acting as crystal nuclei for the subsequent crystal growth that involves both species.

• 出版日期2018-3