中文摘要：

聚乳酸是前景广阔的可降解生物材料，聚乳酸生产的前体——丙交酯的产量和质量是规模化生产聚乳酸的关键．二步法生产丙交酯过程中，会产生大量低分子量的聚乳酸釜底物，经过水解等处理后能够再次用于丙交酯生产．为探索釜底物的循环利用、降低规模化合成的成本，摸索了水解乳酸低聚物为原料生产丙交酯的适宜条件．从分子量水平和成分含量等方面对比了水解乳酸低聚物和新鲜乳酸作为原料，以二步法制备丙交酯的差异．得出的结论是：低聚物水解料中的残留催化剂能够催化聚合和解聚，产率达到28％．

英文摘要：

As dispensable material to prepare polylactide, the purity and cost of lactide effect the quality and price of polylactide. The oligomer dehydrated from oligomer in last reaction can be used as reaction stuff like fresh lactic acid, but the suitable react condition is not clear. This paper researches the difference between react system of lactic acid and oligomer, including the level of average molecular weight, relative content of composition and the influence of added catalyst. The maximal yield of lactide could reach 28%.