溶液聚合法制备聚乳酸的研究

以L-乳酸单体为原料,应用溶液聚合法制备聚乳酸,其中二苯醚为溶剂,采用分阶段脱水的工艺方法。探讨了反应时间,反应温度,催化剂种类及其用量,反应体系的真空度,分子筛等因素对聚合物相对分子质量的影响。采用乌式黏度法测量其相对分子质量,并用FTIR测试手段对聚合物进行结构表征。结果表明,最佳的反应条件为,反应温度170℃,催化剂用量为0.25wt%,聚合反应后期加入分子筛脱水,聚合时间为20h。

Study on the Synthesis of Poly-lactic Acid by Solution Polycondensation

Poly-lactic acid was prepared by solution polycondensation with using L-lactic acid monomer as the raw material, diphenyl ether as solvent, and dehydration process was adopted. The effects of some factors on the molecular weight were investigated, such as reaction time, reaction temperature, catalyst type and amount, the vacuum degree of the reaction system and the molecular sieve, etc. The molecular weight was determined by Ubbelohde viscometer and the structure was characterized by FTIR. The results showed that the optimal reaction conditions were as follows： the reaction temperature was 170℃, the amount of catalyst was 0.25wt%, the polymerization time was 2Oh, and dehydrating with molecular sieve in the later period of polymerization.