国产精品igao视频网网址不卡日韩,亚洲综合在线电影,亚洲婷婷丁香,黄色在线网站噜噜噜

Modified melt polycondensaton of L-lactic acid (LLA) was conducted with a binary SnCl2·2H2O/TSA catalyst system to synthesize high molecular weight poly(L-lactic acid) (PLLA). The effect of the catalyst amount, reaction temperature and
time on the molecular weight and yield of PLLA had been investigated. PLLA with weight-average molecular weight of about 100 000 was successfully synthesized at a yield of 70% via melt polycondensation with 0.4wt% catalysts at 180 oC and under 300Pa for 25 hours. The microstructure, aggregation state and thermal properties of PLLA had been characterized by FT-IR, 1H NMR and DSC, respectively. The resulting PLLAs possess high crystallinity and melt temperature, white to pale yellow color, good film-forming and fiber-forming properties.