POLYMERIZATION OF AQUEOUS LACTIC-ACID TO PREPARE HIGH-MOLECULAR-WEIGHT POLY(LACTIC ACID) BY CHAIN-EXTENDING WITH HEXAMETHYLENE DIISOCYANATE

被引:133
作者
WOO, SI
KIM, BO
JUN, HS
CHANG, HN
机构
[1] Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Taejon, 373-1, Kusong dong, Yusong Gu
关键词
D O I
10.1007/BF00297606
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
In order to synthesize the high molecular weight poly(lactic acid) [PLA], Hexamethylene diisocyanate [HDI] was used as a chain extender connecting the terminal group of polymers. Poly(lactic acid) of high molecular weight, 76000 (M(w)) and 33000 (M(n)), was obtained by using antimony trioxide catalyst after chain-extending with HDI. Without chain-extending, the molecular weight of PLA was about 7000 (M(n)). T-m in the 2nd-scan DSC thermogram was not found when PLA was chain-extended with HDI. In order to check the degree of crystallization of polymers, annealing of these polymers was carried out at 120 degrees C. Peaks of XRD (X-Ray Diffraction) were sharpened as the duration of annealing was lengthened. The analysis of polymers reacted with HDI by H-1-NMR showed the broad peaks at 1.32 and 3.14 ppm assigned to HDI units. The molecular weight of polymers increased with the increase in the mole ratio of -NCO/-OH.
引用
收藏
页码:415 / 421
页数:7
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