【作者】 张莉；

【导师】 李振花；

【作者基本信息】 天津大学 ， 化学工艺， 2010， 硕士

【摘要】 聚乳酸是21世纪备受关注的生物可降解高分子材料,但由于其质脆、耐热性不佳、结晶性差,极大地限制了其应用范围。本实验希望利用工艺方法已成熟的改性蒙脱土与聚乳酸共混,制备纳米高分子复合材料,以改善聚乳酸的结晶性能、热性能、力学性能等。XRD表征表明,改性蒙脱土与一般蒙脱土相比,层间距从1.76nm撑开到2.01nm,层间距明显增大。进而,将改性蒙脱土、一般蒙脱土分别与聚乳酸共混,制备聚乳酸复合材料。经XRD和TEM表征,改性蒙脱土在聚乳酸中层间距撑大到3.39nm,比一般蒙脱土分散效果好。并且,在不同加工温度和改性蒙脱土添加量下分别制备纳米复合材料,XRD和TEM表征结果表明,加工温度固定在150℃、改性蒙脱土添加量为6%时,改性蒙脱土的分散效果最好。进一步,6%改性蒙脱土/聚乳酸与纯聚乳酸的DSC图表明,蒙脱土可有效诱导聚乳酸异核结晶,抑制冷结晶,提升玻璃转移温度等。恒温DSC图表明,蒙脱土起异相成核剂作用,可有效提高聚乳酸的成核速率和结晶成长速率。TGA分析表明,蒙脱土可提高聚乳酸热裂解温度。利用电子拉力试验机分析,聚乳酸力学性能在6%蒙脱土添加量时达到最优。最后,为了进一步了解相容剂对聚乳酸材料性能的影响,我们还进行了关于聚草酸酯合成的初步研究。实验表明,经核磁共振分析,乙烯与草酸酯的聚合物中有10%左右副产物。而TGA、DSC图表明,随碳链延长,聚乙烯草酸酯和聚丁烯草酸酯,5 wt%热重损失从230℃提升至278℃,熔点从178℃降低到100℃。另外,聚草酸酯高分子结晶性能良好,有望作为新的成核剂诱导聚乳酸结晶。更多还原

【Abstract】 Poly (1actic acid) (PLA) is a very important kind of commercial biodegradable polymer with wide applications in the 21st century.However,its brittle character, lower thermal stability and bad crystalline ability restrict its further applications.Polymer blending is an efficient method to improve the performance of polymer.We used the modified montmorillonite(MMA) to improve the performance of PLA through the melting blending. The level spacing enlarged from 1.76nm to 2.01nm through the XRD, which indicated that the modifier successfully inserted the layered montmorillonite. Then, through the XRD and TEM, the level spacing of PLA/MMA changed to 3.39nm, which indicated the modified MMA scattered better than the normal MMA in PLA. And when the processing temperature fixed at 150℃and the proportion at 6%, the modified MMA scattered best.Through the DSC, 6% modified MMA could significantly increase the crystalline ability and promote the glass shift temperature. Modified MMA increased the rate of crystallization by the constant temperature DSC. The mechanical properties achieved superiorly with 6wt% MMA. Modified MMA could also promote the thermal decomposition temperature of PLA by TGA.Finally, we carried on research about the synthesis of poly(ethylene oxalate) (PEO) and poly(butene oxalate) (PBO). The experiment indicated that the melting point of PEO and PBO respectively be 178℃and 100℃. The 5% weight loss temperature promoted from 230℃to 278℃, which indicated that lengthening the carbon chain could promote the thermostability effectively.更多还原