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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。
Using L-lactic acid monomer as raw material, polylactic acid is prepared by solution polymerization method, in which diphenyl ether is used as solvent, and the process of dehydration in stages is adopted. The effects of reaction time, reaction temperature, catalyst type and amount, vacuum degree of the reaction system, molecular sieve and other factors on the molecular weight of the polymer were discussed. The relative molecular mass of the polymer was measured by the Wu viscosity method, and the structure of the polymer was characterized by FTIR test. The results showed that the optimal reaction conditions were as follows: the reaction temperature was 170 ℃, the amount of catalyst was 0.25wt%, the molecular sieves were dehydrated after the polymerization, and the polymerization time was 20h.