生物降解材料聚乳酸的合成与表征

以乳酸(LA)为原料,采用直接熔融法和固相缩聚法,通过优选催化剂、分步除水、连续通氮气和高真空缩合等工艺,直接缩聚合成可用于改性的聚乳酸(PLA).研究了直接熔融法和固相缩聚法的聚合时间、体系真空度、聚合工艺等对聚乳酸分子量的影响.通过用酸值变化来监测反应的进程,用粘度法测定了产物的粘均分子量,并以红外光谱对产物进行了表征.结果表明,熔融法的最佳工艺为:辛酸亚锡为催化剂(0.5 wt%),聚合温度175℃,聚合时间12 h,体系真空度30 Pa;固相缩聚法的最佳工艺:辛酸亚锡为催化剂(0.5 wt%)、体系真空度60 Pa、聚合温度150℃、聚合时间10 h.

Synthesis and characterization of biodegradable material PLA

The direct melting polycondensation methods along with the improved process of catalysts,dehydration,nitrogen and vacuum pressure were adopted to synthesize the biodegradable material of poly(lactic acid)(PLA) from lactic acid.The polymerization process was monitored by chemical titration and the molecular weight was measured by viscosity method.The resultant PLA was characterized by FT-IR.The influences of polymerization time,temperature and vacuum pressure on the viscosity molecular weights of PLA were discussed.The optimum reaction conditions for direct melting polycondensation method were: 0.5wt% stannous octoate as catalyst,polymerization time 12h at 175℃ and vacuum degree 30Pa.The optimum reaction conditions for solid-phase polycondensation were: 0.5wt% stannous octoate as catalyst,polymerization time 10h at 150℃ and vacuum degree 60Pa.