论文部分内容阅读
采用{[(2-ArN=C(Me))2C5H3N]FeCl2}作为齐聚催化剂[其中Ar=2,4-C6H3(CH3)2和Ar=2-Cl-4-CH3C6H3],商品化的Ziegler-Natta催化剂作为共聚催化剂,分别组成双功能催化体系A[Ziegler-Natta/MAO/TEA/Fe-CH3]和B[Ziegler-Natta/MAO/TEA/Fe-Cl],催化乙烯原位共聚。通过调节不同的聚合条件制备了具有不同支化度、不同分子量及其分布的LLDPE,利用13 C-NMR、流变仪、GPC(示差/光散射)等表征手段,研究了所得高聚物的结构特征。结果表明,该催化体系制备LLDPE样品的支链含量和齐聚物的碳数分布规律是一致的,LLDPE中既有短支链也有较长的支链,聚合物的分子量分布较宽,为聚合物的力学性能和可加工性能提供了更大的调节余地。通过对样品的零剪切粘度、模量、交叉频率、损耗角以及剪切变稀特征等的考察,零剪切粘度与重均分子量的指数关系大于3.8,可以判断被分析的样品含有长支链。分别采用A和B催化剂体系制备的样品作比较,B组样品含有长支链组分,存在较多的高分子量尾端。
A commercial catalyst Ziegler was synthesized using {[(2-ArN = C (Me)) 2C5H3N] FeCl2} as the oligomerization catalyst [where Ar = 2,4- C6H3 (CH3) 2 and Ar = 2-Cl-4-CH3C6H3] -Natta catalyst as a copolymerization catalyst to form the bifunctional catalytic system A [Ziegler-Natta / MAO / TEA / Fe-CH3] and B [Ziegler-Natta / MAO / TEA / Fe-Cl] By adjusting different polymerization conditions, LLDPE with different branching degrees, different molecular weights and their distribution were prepared. The 13 C-NMR, rheometer and GPC (differential optical / Structure. The results showed that the branched chain content and the carbon number distribution of the oligomers of LLDPE were the same. The LLDPE had both short and long branches. The molecular weight distribution of the polymer was broad, The mechanical properties and machinability of the material provide more room for adjustment. By examining the zero-shear viscosity, modulus, crossover frequency, loss angle and shear thinning characteristics of the samples, the exponential relationship between zero-shear viscosity and weight-average molecular weight is greater than 3.8, and it can be judged that the sample to be analyzed contains a long branch chain. Compared with the samples prepared by A and B catalyst systems respectively, the samples in group B contained long-chain components and more high-molecular-weight tail.