摘要
合成了一种新型α 二亚胺镍配合物———α 萘基丁二亚胺氯化镍 ,此配合物作为催化剂在MAO的活化下催化乙烯聚合得到支化聚乙烯 ,聚合活性高达 7 18× 10 5gPE molNi·h ,1 3C NMR、FTIR测试结果表明制备的聚乙烯含有末端双键 ;GPC结果表明所制备的聚乙烯分子量呈双 (宽 )峰分布 ,其原因有两个 ,一是此催化剂能产生分子量较低的α 烯烃 ,在聚合过程中一部分α 烯烃会“就地”与乙烯原位共聚形成分子量较高的聚合物 ,二是此催化剂存在立体异构体 ,而不同异构体在MAO活化下形成的活性中心的配位环境不同 ,因而得到的聚乙烯的分子量也不同 .研究了聚合温度、聚合压力、铝镍摩尔比 (nAl nNi)对催化活性、聚乙烯分子量、支化度的影响 .聚乙烯的分子量随聚合温度的升高而下降 ,支化度增大 ,熔点则降低 .
A nickel catalyst,bis( α naphthyl) 2,3 butanediimine nickel(Ⅱ)dichloride {[C 10 H 7— N C (CH 3)C (CH 3) NC 10 H 7 ]NiCl 2} was synthesized and then activated by methylaluminoxane(MAO).By using this catalytic system branched polyethylenes(PE)of bimodal (wide) molecular weight distribution(MWD) were prepared.The effects of various conditions,including the polymerization temperature ( T p),ethylene pressure and n Al / n Ni on the catalytic activity,molecular weight,degree of branching and branching types of PE were investigated.The catalytic activity and the resulting polymer microstructure were sensitive to the polymerization temperature.The microstructure of the resulting PE was determined by FTIR and 13 C NMR.According to Gel Permeation Chromatography(GPC),the resulting PE exhibited a bimodal molecular weight distribution.The influence of the existence of three possible stereo isomers of the Ni single site catalyst with unsymmetrical imino substituted bulky ligands on the molecular weight distribution was discussed.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2005年第2期240-243,共4页
Acta Polymerica Sinica
基金
国家自然科学基金资助项目 (基金号 2 0 1740 5 0 )
