A COMPARISON OF (N-BUTCP)(2)ZRCL2 AND OTHER SIMPLE METALLOCENES WITH BRIDGED ET(IND)(2)ZRCL2 AND ME(2)SI(IND)(2)ZRCL2 CATALYSTS IN ETHENE PROPENE COPOLYMERIZATION/

A study was made of the behaviour of four non-bridged metallocenes, in particular (n-butCp)(2)ZrCl2 in ethene/propene (E/P) copolymerization , and the findings were compared with those for bridged Et(Ind)(2)ZrCl 2 and Me(2)Si(Ind)(2)ZrCl2 catalysts. Methylaluminoxane was used as a cocatalyst in all polymerizations. The influence of the catalyst struc ture on the propene content, the reactivity ratios, the comonomer dist ribution in the polymer backbone, molar mass, molar mass distribution, density and melting point of the synthesized material were of interes t. The bridged metallocenes were found to be more active catalysts for propene incorporation than the non-bridged ones. The comonomer distri butions of all polymers except those obtained with an Ind(2)ZrCl(2) ca talyst were random. At the same propene molar content in the copolymer , densities and melting points were lower for materials synthesized wi th non-bridged catalysts than for materials synthesized with bridged c atalysts due to the lack of chirality in the catalysts of C-2v symmetr y. Except Cp(2)ZrCl(2), the non-bridged metallocenes produced higher m olar mass copolymers than their bridged analogues. Polydispersities of the materials varied with the catalyst and no uniformity of behaviour was detected for the simple metallocenes. Copyright (C) 1996 Elsevier Science Ltd