Copolymerization of ethylene and norbornene with ziconocene/methyl aluminoxane catalyst

Abstract

In this research, ethylene and norbomene copolymerization was carried out with rac-ethylenebis (indenyl) zirconium dichloride catalyst system in the presence of methylaluminoxane as a cocatalyst (rac-Et(Ind)2ZrCl/MAO, Catalyst 1). Effects of reaction conditions i.e. [Al]MAơ/[Metal] ratio, catalyst concentrations and reaction temperatures in copolymerization are summarized. The effect of different types metallocene catalyst such as rac-Et[Ind]2ZrCl2, (n-BuCp)2ZrCl2, Cp2ZrCl2, Cp2TiCl2, CpTiCl3, Cp*TiCl3 and Cp*TiMe3 indicated that Catalyst 1 showed the highest catalytic activity and gave copolymers containing the highest amount of norbomene and the lowest crystallinity. However, the catalyst system of CpTiCl3, Cp*TiCl3 and Cp*TiMe3 can not be conducted copolymerization of ethylene and norbornene. The comparison between Catalyt 1 and biscyclopentadienylzirconium dichloride (Cp2ZrCl2/MAO, Catalyst 2) catalyst systems, Catalyst 2 showed higher activity than Catalyst 1 in homopolymerization of ethylene however, an opposite trend in copolymeriztion of ethylene and norbomene was found for both systems. The catalytic activity decreased with increasing norbomene concentrations for both zirconocene catalyst systems. The decreased activity for Catalyst 1 is higher than that of Catalyst 2. Ethylene and norbomene copolymerization with rac-Et[Ind]2ZrCl2/MAO catalyst system was performed in toluene or xylene as a solvent. For the both systems, the catalytic activity and norbomene content in copolymer decreased with increasing the polymerization times therefore, the effect of different solvents was not observed. However, ethylene and norbomene copolymerization was not proceeded in the system which used aliphatic solvents, i.e. 1-hexane, 1-heptane and 1-decane.