Combined effect of modified zeolite 13X and β-nucleating agent on improving β-crystal content and toughening polypropylene random copolymer

Although addition of β-NUCLEATING agent directly into homo-polypropylene(PPH) is a useful method to improve β-CRYSTAL content and toughen PPH, polypropylene random copolymer(PPR) makes this method powerless due to its random structure and low crystallinity. In this study, the-nucleated PPR with high β-CRYSTAL content was prepared by a novel high effective β-NUCLEATING system which consists of-nucleation agent(TMB-5) and modified zeolite 13X(M13X). It was found that M13X and TMB-5 had a synergistic influence on improving β-CRYSTAL content and toughening PPR. The content of β-CRYSTAL in PPR/M13X/TMB-5 was significantly larger than the sum of that in PPR/M13X and PPR/TMB-5. Besides,fracture behavior, phase morphology and relaxation of matrix chain segments were also investigated. The results showed that M13X and TMB-5 improved the mobility of amorphous chain segments at low temperature and contributed to much energy dissipation. This work provides a powerful method to modify PPR.     

高分子科学实验教学改革初探

设想将高分子化学、高分子物理和高分子成型加工三门实验课程有机地串联起来,组建成一门包括从高分子材料设计(用计算机软件进行分子设计、性能模拟)、聚合物合成、性能测试(物性表征)到加工成型(制作成高分子材料制品),能环环相扣、互动式的、柔性化的高分子科学实验课程;提出了初步的实践方案.     

水溶性低分子壳聚糖的制备

Oxidative degradation of chitosan by H2O2-NaClO mixed oxidant is studied in acidic condition.The effects of concentration of H2O2,reactive temperature and reaction time on oxidative degradation reaction are studied.The results show that the method of oxidative degradation of chitosan with H2O2-NaClO mixed oxidant is effective for preparation of water-soluble chitooligosaccharides.     

聚乙烯醇缩丁醛热稳定性能的研究

本文通过两步加料法合成了聚乙烯醇缩丁醛(PVB)树脂并对其热稳定性进行了研究.由热老化和热重数据可知,碱金属和碱土金属氢氧化物NaOH、Ca(OH)2、Ba(OH)2的加入分别在不同程度上提高了PVB树脂热稳定性,比较发现,Ba(OH)2的热稳定效率最高.此外,本文通过红外光谱和紫外光谱分析,对碱的热稳定机理进行了探讨,结果表明碱之所以能够延缓PVB高温下的热降解,是因为碱可以阻碍PVB受热后缩醛开环和共轭结构的形成.