改性Ziegler-Natta体系催化乙烯/1-辛烯共聚合反应

采用改性Ziegler-Natta(Z-N)催化体系(n-BuO)TiCl₃/MgCl₂/AlEt₃催化乙烯/1-辛烯共聚合。考察了聚合温度、Al/Ti物质的量比、单体投料比及乙烯压力对聚合行为的影响，并与传统Z-N催化体系TiCl₄/MgCl₂/AlEt₃催化乙烯/1-辛烯共聚合行为进行了对比研究。采用GPC，DSC，¹³C-NMR，SEM对共聚物的结构、形态及性能进行了表征。结果表明，改性Z-N催化体系催化乙烯/1-辛烯共聚合时，1-辛烯的共聚能力明显高于传统Z-N催化体系，在共聚物中1-辛烯的插入量达2.26%（摩尔分数），而传统Z-N催化剂1-辛烯的插入量仅为0.34%（摩尔分数）；Al/Ti物质的量比及单体投料比对催化剂的活性、1-辛烯的插入量、共聚物的分子量与分子量分布及共聚物的微观结构有明显的影响；根据¹³C-NMR结果计算了单体的竞聚率:r_E=55.00，r_O=0.023，其乘积r_E· r_O=1.27，表明该聚合物为无规共聚物。

Copolymerization of ethylene and 1-octene catalyzed by a modified Ziegler-Natta catalyst

A novel modified supported Ziegler-Natta catalyst,(n-BuO)TiCl3/MgCl2 has been prepared and employed for ethylene/1-octene copolymerization,with AlEt3 as cocatalyst.The influence of varying the polymerization temperature,the Al/Ti molar ratio,the feed molar ratio of ethylene to 1-octene and the ethylene pressure on the copolymerization reaction were investigated.The structure,properties and morphology of the copolymer were characterized by 13C-NMR,GPC,DSC and SEM.It was found that the catalytic activity in ethylene/1-octene copolymerization of the modified Ziegler-Natta catalyst was higher than that of the traditional Ziegler-Natta catalyst.The Al/Ti molar ratio and the feed molar ratio of ethylene to 1-octene have obvious effects on the catalytic activity,the comonomer content within the copolymer chain,the molecular weight and molecular weight distribution,and the microstructure of the resulting copolymer.Compared with the traditional Ziegler-Natta catalyst for ethylene/1-octene copolymerization which gives a comonomer content of 0.34%,the modified Ziegler-Natta catalyst showed higher activity for ethylene/1-octene copolymerization,and the comonomer content within the copolymer chain reached as high as 2.26 mol%.The microstructure of the copolymer was determined and the reactivity ratios of the monomers were confirmed by 13C-NMR.Values of rE=55.00 for ethylene and rO=0.023 for 1-octene with rE·rO=1.27 were obtained,suggesting the tendency for random distribution of the comonomers within the copolymer chain.