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K. Szczegot, J. Ejfler, I. Sibelska-Wiercigroch


Ethylene polymerization on vanadium-magnesium catalysts activated with organoaluminium compounds

Polimery 1996, No 7-8, 406


DOI: dx.doi.org/10.14314/polimery.1996.406

Summary

Complexes (I)—(V) of vanadium(III) chloride with Lewis bases like tetrahydrofuran, ethyl acetate and ethyl malonate, were used as precursors of vanadium-magnesium catalysts for polymerization of ethylene. When treated with organoaluminium compounds the pure complexes showed no catalytic activity. After having been ball-milled with [MgCl2(THF)2] used as carrier, the complexes catalyzed the polymerization at rates up to 260 kg PE (gVh'1). A chlorinated hydrocarbon added to the polymerization medium raised the catalyst activity. The resulting PE had a high molecular weight and a very narrow molecular weight distribution, indicative of highly homogeneous active centers. The density of PE was rather low, 0.931—0.941 g em'3; bulk density, 105—122 gdm'3; degree of crystallinity, 50.0—60.8 %. The catalysts prepared from dimeric complexes (II)—(IV) of vanadium(III) chloride presumably contain dimeric active centers on which polymer chain growth occurs on the two vanadium atoms.


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