蒙脱土负载聚合催化剂用于乙烯原位共聚制备LLDPE

将蒙脱土 (MMT)负载的聚合催化剂rac Et(Ind) 2 ZrCl2 和均相低聚催化剂 { [(2 ArNC(Me) ) 2 C5H3N]FeCl2 } (Ar=2 ,4 C6 H4 (Me) 2 )组成双功能催化体系用于乙烯原位共聚制备线性低密度聚乙烯 (LLDPE) .通过调节两种催化剂之间的比例和MAO的用量制备了一系列支化度不同的LLDPE产品 .聚合反应动力学曲线表明 ,两种催化剂表现出各自的乙烯吸收特征 ,蒙脱土负载化的共聚催化剂催化乙烯聚合时反应平稳易控制 .DSC曲线表明 ,聚合物的熔点和结晶度随Fe Zr的增大而减小 .用密度梯度法测得的聚合物密度随Fe Zr的增大而降低 .从1 3C NMR谱图上可以看到 ,得到的聚合物是LLDPE ,其支化度随Fe Zr的增大而增大 ,聚合物中仍含有未共聚的α 烯烃 ,这一点从GPC上也能得到验证 .扫描电镜 (SEM)照片表明用这种双功能催化剂共聚得到的LLDPE具有良好的形态

PREPARATION OF LLDPE BY in situ COPOLYMERIZATION OF ETHYLENE WITH POLYMERIZATION CATALYST SUPPORTED ON MONTMORILLONITE

Linear low-density polyethylene (LLDPE) has been prepared by in situ copolymerization of ethylene with a dual functional catalyst,which was composed of rac-Et(Ind) 2ZrCl 2 supported on montmorillonite (MMT) and {[(2-ArNC(Me)) 2C 5H 3N]FeCl 2}(Ar=2,4-C 6H 4(Me) 2) oligomerization catalyst.A series of LLDPE with different branching degrees were obtained by adjusting the molar ratio of Fe and Zr (Fe/Zr),the molar ratio of Al and (Fe+Zr) (Al/(Fe+Zr)) as well.The kinetics curves of polymerization show that the two catalysts exhibit respective catalytic characterizations,and the activity of copolymerization catalyst is more smoothly after supported on MMT.As increasing the Fe/Zr ratio,the densities of polymers measured by density gradient method and the melting points of polymers obtained from DSC decrease. 13C-NMR shows that the polymers are LLDPE,and their branching degrees increase as the increasing of the Fe/Zr ratio.At the same time,there are some unreacted α-olefins in polymers,which were confirmed by 13C-NMR and GPC.The SEM shows that the polymerization catalyst supported on MMT may produce LLDPE with better morphology than that produced by the catalyst in homogeneous.