The product ratio was increased to 45 % from 30 % . furthermore , lactide was recycled from the ethyl acetate recrystallization solution , and structure was investigated with ir and uv spectrum . the result indicated that the process is suitable and feasible , and the product ratio is beyond 40 % 本文在总结了目前众多聚乳酸单体? ?丙交酯的合成技术的基础上，选用减压蒸馏工艺并加以改进，设计出最佳的实验装置，使丙交酯的产率从30提高到45 ，并对重结晶后的母液进行有效的回收，回收率也能达到40 ，对回收后的丙交酯进行了测试分析，证明了回收过程的可行性。
( 5 ) the article also investigate the recrystallization condition of crude lactide and point out that it also an important factor have influence on the purification production ratio . ( 6 ) give the kinetics equation of depolymerization reaction . by determination the degree of polymerization ( dp ) of the reaction system , we can get the kinetics data of the reaction 本文建议使用乙酸乙酯和异丙醇混合溶剂( 6 ： 4 )对丙交酯粗产物进行重结晶； ( 6 )提出解聚反应的动力学方程，认为它是一个可近似处理为一级反应的连续反应，并可通过测定体系的平均聚合度的方法来得到包括活化能在内的反应动力学数据。
The traditional synthetic method of 2 , 5 - dithiol - benzene - 1 , 4 - diamine dihydrochloride ( dtbda ) is characterized by a louger time of reaction , heigher consumption on chemicals and lower yield . but by changing the solvent for synthesis , the reaction time is shortened and the consumption on chemicals is lowered 通过改变合成的溶剂对已报道的合成二巯基苯二胺二盐酸盐方法进行改进，克服了需经很长周期、耗用大量的反应试剂和重结晶溶剂、产率较低的缺点.改进的方法缩短了产物制备时间，减少了原料的成本消耗，效果明显
