Ethylene and propene were homopolymerized with 11 different metallocene-methylaluminoxane (MAO) catalysts 1-11 using a constant set of parameters. The catalytic activity of the two unbridged and 9 ansa-metallocenes as well as the properties of the polymers, such as molecular weight, width of molecular weight distribution, melting point, and, with polypropene, chain microstructure, were investigated. It was found that structure variations of the catalysts cause rather different catalytic behaviour, which further diversifies the performances with the two different monomers. In some cases this comparison allows insight into the nature of the influencing factors. 0 1992, Huthig & Wepf Verlag, Basel CCC 0025-1 16)3/92/$05,00 Standardized polymerizations of ethylene and propene with . . . Scheme 1: 6 : M t z Z r 7 : Mt=Hf 9 4-R=CH, (2 isomers) 5: R-H

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