【作者】 方大庆；

【导师】 王华林；

【作者基本信息】 合肥工业大学 ， 应用化学， 2004， 硕士

【摘要】 本文以D，L-乳酸为原料，采用丙交酯开环聚合和直接熔融聚合制备出聚D,L-乳酸(PDLLA)，并对PDLLA降解性能进行了研究。 丙交酯开环聚合制备PDLLA的关键在于中间体D，L-丙交酯(DLLA)的制备，研究了催化剂、反应温度、反应时间等因素对DLLA产率的影响，通过在反应体系中加入稀释剂乙二醇，DLLA的馏出温度明显降低，避免了DLLA在蒸馏过程中产生碳化现象，并使DLLA的平均产率由36.8％提高至51.3％，制备的PDLLA分子量最大值达18.4万。利用DSC、XRD、IR等分析测试技术对DLLA和PDLLA的性能和结构进行相关的测试和表征。 直接熔融聚合制备PDLLA的关键在于小分子水的脱除，制备出的PDLLA分子量明显低于丙交酯开环聚合制备的PDLLA。通过研究催化剂、反应温度、反应时间等因素对PDLLA分子量的影响，优化了工艺参数。 通过研究PDLLA的生理盐水降解性能和热降解性能，发现PDLLA在生理盐水中首先发生分子量降解，然后产生重量损失，且降解过程中生成具有晶体结构特征降解产物；PDLLA的热降解是一个无规的断裂过程，在100℃～250℃范围内，PDLLA的分子量迅速发生降解，在250℃以上，低聚物相继发生裂解，产生重量损失。更多还原

【Abstract】 (D, L) lactic acid was used to prepare poly (D, L) lactic (PDLLA) and the degradation of PDLLA was studied in this paper.The key of indirect method to synthesize PDLLA is the preparation of intermediate (D, L) lactide (DLLA). The affections on the yield of DLLA caused by catalyst, temperature and time etc. were studied. By using ethylene glycol as diluent, the distillate temperature of DLLA was lowed and the carbonization phenomenon could be avoided, which caused the yield of DLLA increasing from 36.8% to 51.3%. The molecular weight of PDLLA prepared by this method could reach 184,000. DLLA and PDLLA was characterized and analyzed by DSC, XRD and IR.The key of direct method to synthesize PDLLA is the exclusion of H2O from reaction system. Comparing with the indirect method, the molecular weight of PDLLA prepared by direct method was lower. In order to optimize technology parameters, the affections on PDLLA molecular weight caused by catalyst, temperature, time etc. were studied.The hydrolytic degradation and thermal degradation of PDLLA were investigated. The hydrolytic degradation research results showed that the PDLLA molecular weight was first degraded, then the weight loss happened in normal saline, and the water soluble crystallizable oligomers were formed during the process of degradation. The thermal degradation research results showed that the thermal degradation of PDLLA is a random breaking process, the molecular weight was degraded at range of 100癈~250癈, only above 250癈, the weight loss was found.更多还原