writer：Tao Yu, Jie Ren, Shuying Gu, Ming Yang
keywords：poly(lactic acid), polycarbonate diol, polycondensation, chain extension, block copolymers
source：期刊
specific source：Polymer International. 2009; 58: 1058-1064
Issue time：2009年
BACKGROUND: Poly(lactic acid) (PLA) has received much attention as a biodegradable polymer. But the physical properties of PLA, such as brittleness, limit its wider applicability. Copolymerization polymers ing soft blocks provides a useful method to
improve the mechanical properties of PLA.
RESULTS: Poly(lactic acid)-block-(polycarbonate diol) (PLA-PCD) copolymers were synthesized using a two-step process with polycondensation and chain extension reactions. The effect of polycarbonate diol content on the prepolymer properties was
studied. The chain-extended products were characterized using 1 H NMR, F and. The effect of the NCO/OH ratio on the properties of the chain-extended products, including the mechanical properties and thermal properties, was studied. eight-average
molecular weight of the product can reach 210 000 g mol?1 when the molar ratio of –NCO to –OH is 3 : 1.
CONCLUSION: The PLA-PCD copolymers obtained can crystallize, and the crystallinity decreases with chain-extension reaction. The products exhibit superior mechanical properties with elongation at break above 230%, which is much higher than that of
PLA chain-extended products. The products have a good potential for packaging applications.