【作者】 石梁萍；

【导师】 王远亮； 罗彦凤；

【作者基本信息】 重庆大学 ， 生物医学工程， 2006， 硕士

【摘要】 聚乳酸是一种公认的用途广泛、前景广阔的完全可降解生物材料。聚乳酸具有良好的可塑性、生物相容性和生物降解性,完全降解产物是二氧化碳和水,对环境无毒无害,因此在农业、日化和生物医学工程领域都有广泛的应用。合成聚乳酸的原料是乳酸,可以以淀粉为原料通过生物发酵获得,来源丰富。丙交酯开环聚合制备聚乳酸是目前研究得较多的聚乳酸聚合方法,能够获得高分子量聚乳酸,这种方法对丙交酯的质量和成本提出了较高的要求。丙交酯的合成一般是以廉价的乳酸为原料,单次合成会产生较高分子量的聚乳酸低聚物,理论上经过充分水解,能够被再次利用合成丙交酯。本实验以循环利用丙交酯合成后的釜底物为目的,研究了以水解料乳酸低聚物为原料合成丙交酯的可行性和优化条件。首先对水解条件进行了探索和优化,对水解料的成分进行了表征,尤其是对水解料中残留的催化剂含量和活性作了测定和验证。其次用新鲜乳酸和水解料分别进行了合成丙交酯的实验,采用了正交实验方法探讨了催化剂加入量、二脱水反应时间和新旧料混合比例对产率、产物含酸率等结果的影响,获得最优的生产工艺为新催化剂0.7%、新旧料比例2:1、二脱水反应时间2h,最高产率为40%。在生产设备上重现此工艺得到产物含酸率12.1%。最后,对低聚物水解料生产的丙交酯进行了纯化和聚合,与新鲜乳酸合成的丙交酯和聚乳酸的结构用红外光谱进行了比较,结论是两种体系生产的丙交酯和聚乳酸没有显著差异。更多还原

【Abstract】 PLA(Poly Lactide) was a kind of wildly used synthetical material with wonderful biologic compatibility and biodegradable properties. When finally degradated,it become CO2 and H2O, which were harmless and non-toxic to environment. As advanced material, PLA can be wildly used in many field like agriculture, commodity chemistry and biomedicine.The raw material of PLA is Lactic acid, which obtained from starch with fermentation. The Lactide ring-opening polymerization is the most important way to produce PLA, which obtain high molecular weight product. The quality and the price of Lactide influence the final result.In this paper, synthesis of lactide from oligomer was discussed. Usually, the lactide synthesized from fresh lactic acid. But a lot of oligomer left after reactivity, which can be reused when finally hydrolyzed. This dissertation focused on the investigation of the hydrolyzing conduction and composition of oligomer, especially the rudimental catalyst, which was excessive because of reactivity cumulating. The best technical method of increasing the rate of product and reducing the acid content was investigated by means of orthodoxical experiment. The results showed the amount of catalyst was the only prominent factor that influenced the rate of the product and the acid amount in the experiment. The optimums of the reactivity condition was proved that the extra catalyst was 0.7%, the dehydration time was 2h, the proportion of fresh lactic acid and the oligomer was 2:1.The condition was tested in the production equipment, the acid amount reduced to 12.1%,which was close to the result of fresh lactic acid reaction system. In the end, the lactide produced from oligomer polymerized to poly(D,L-lactide), which was characterized by IR spectrum, TG and DSC. The structure of lactide and poly(D,L-lactide) produced from fresh lactic acid and oligomer were proved to be the same.更多还原