聚乳酸的间接合成研究

Indirect synthesis of polylactic acid

以D,L乳酸为原料、ZnO为催化剂,制备中间体丙交酯;再以丙交酯为原料、ZnO为催化剂,开环制得了较高相对分子质量的聚乳酸。用红外光谱仪(IR)对丙交酯及聚乳酸进行了表征,并讨论了影响丙交酯产率、聚乳酸相对分子质量的主要因素。得出在压力1.7×104Pa、催化剂质量分数为2.2%的条件下,两步脱水后制得的丙交酯经多次纯化后,其最大产率可达31%。在压力1.7×104Pa、催化剂质量分数0.06%时,可得到相对分子质量为1.1×105的聚乳酸。

Lactide was prepared from D,L-lactic acid with the zinc oxide as the catalyst.Then,the higher molecule weight polylactic acid was obtained from lactide with the zinc oxide as the catalyst by ring-opening.The lactide and polylactic acid were charactered by IR,and the major effect factors of lactide yield and molecular weight of polylactic acid were discussed.As a result,when the pressure was 1.7×10^(4) Pa and the catalyst content was 2.2%,the biggest yield of lactide can reach 31% after purifying several times by two steps dehydration.When the pressure was 1.7×10^(4) Pa and the catalyst content was 0.06%,the polylactic acid with 1.1×10^(5) relative molecule weight was obtained.