论文部分内容阅读
采用二步法合成了 (D ,L)型聚乳酸 (PLA) ,将合成出来的聚乳酸进行了纯化、分子量测定、红外光谱分析及DSC谱图分析 ;研究了辛酸亚锡的用量对聚乳酸的分子量的影响、重结晶次数对聚乳酸分子量的影响、分子量与Tg之间关系等。结果表明在丙交酯的开环聚合中 ,引发剂与单体的比例对聚乳酸的分子量的大小起决定性作用 ,辛酸亚锡与丙交酯的比例过高或过低 ,均只能得到较低分子量的聚乳酸。开环聚合反应属逐步聚合反应 ,引发剂与单体的比例过高 ,活性点过多 ,不易得到较高分子量的聚乳酸。引发剂与单体的比例过低 ,活性点过少 ,单体难以完成发生聚合。重结晶次数越多 ,单体的旋光性能改善 ,纯度笪以提高 ,在一定引发剂与单体配比条件下 ,PLA的分子量大小可以得到控制
The poly (D, L) -lactic polylactic acid (PLA) was synthesized by two-step method. The polylactic acid was purified, molecular weight, IR and DSC were analyzed. The effect of stannous octanoate Of the impact of molecular weight, the number of recrystallization polylactic acid molecular weight, the relationship between molecular weight and Tg. The results show that in the ring-opening polymerization of lactide, the ratio of initiator to monomer plays a decisive role on the molecular weight of polylactic acid. The ratio of stannous octoate to lactide can only get better Low molecular weight polylactic acid. Ring-opening polymerization is a gradual polymerization reaction, the ratio of initiator and monomer is too high, too many active sites, not easy to get higher molecular weight polylactic acid. The initiator and the monomer ratio is too low, the active point is too small, the monomer is difficult to complete the polymerization. The more the number of recrystallization, the improvement of the optical properties of the monomer, the purity 笪 to improve, in a certain ratio of initiator and monomer conditions, PLA molecular weight can be controlled