齐格勒-纳塔等规聚丙烯和茂金属等规聚丙烯共混物结晶热力学研究

通过机械共混的方法制备了不同质量分数的齐格勒纳塔等规聚丙烯和茂金属等规聚丙烯的共混物 ,并对其结晶热力学进行了研究和比较。通过实验发现 ,共混物有共晶形成 ;当茂金属等规聚丙烯的比例占半数以上时 ,随着齐格勒纳塔等规聚丙烯含量的提高 ,共混物的熔点增加较为明显 ;当齐格勒纳塔等规聚丙烯的含量超过 5 0 %时 ,随着茂金属等规聚丙烯含量的降低 ,共混物的熔点变化不明显。

Study on the distribution of active centers in novel low Ti-loading MgCl2-supported Ziegler-Natta catalyst

Novel MgCl2-supported Ziegler-Natta (Z-N) catalysts prepared using a new one-pot ball milling method can effectively control the amounts of Ti-loading in the catalysts. Complex GPC data on polypropylene synthesized by these novel catalysts were analyzed using the method of fitting the molecular weight distribution (MWD) curves with a multiple Flory-Schulz function. It was found that multiple active centers exist in these novel catalysts. Detailed study of the effects of the Ti-loadings in the catalysts on the distribution of the active centers showed that the Ti-loadings in the novel MgCl2-supported Z-N catalysts might affect the proportion of each type of active centers; and might be the main factor responsible for the effect of the Ti-loadings on the microstructure, the molecular weight and molecular weight distribution width of the resultant polymer, the catalytic activity and polymerization kinetics.

miPP/ziPP共混体系的流动性能

首次对茂金属聚丙烯 (mi PP) /齐格勒 -纳塔聚丙烯 (zi PP)共混体系的流动性进行了系统的研究。研究发现 ,在 mi PP/zi PP共混体系中 ,mi PP含量的变化改变了共混体系的相结构 ,这种相结构会随着温度和剪切速率的变化而产生明显的变化 ,从而改变了体系的流动性能 。