Abstract: Disclosed is a process for preparing high molecular weight ethylene-.alpha.-olefin elastomers, preferably an ethylene-propylene elastomer, by liquid phase polymerization of the requisite monomers in the presence of a metallocene/alumoxane catalyst complex. Preferably, the process is carried out as a slurry polymerization utilizing the metallocene/alumoxane catalyst in supported form on a silica gel support with the .alpha.-olefin monomer maintained in liquid state and used in excess to serve as a polymerization diluent. The metallocene component of the catalyst by which the process is practiced is of the formula: ##STR1## wherein M is zirconium, titanium or hafnium; R.sup.1 and R.sup.2 are independently a C.sub.1 -C.sub.20 linear, branched or cyclic alkyl group; X an alkyl, aryl, halide, hydride or oxygen bridge of a zirconocene dimer; "y" and "z" are independently numbers 0, 1 or 2; and M is preferably zirconium.

Abstract: A process for producing a high molecular weight EPDM elastomer having low crystallinity using a bridged bis-metallocene-alumoxane catalyst wherein the metallocene component of the catalyst has the formula: ##STR1## wherein "M" is titanium, zirconium or hafnium; each "R.sup.1 " independently is a C.sub.1 to C.sub.20 linear, branched or cyclic alkyl group or a C.sub.2 to C.sub.4 alkylene which forms a fused ring system; "R.sup.2 " is a C.sub.1 to C.sub.6 linear, branched or cyclic alkylene group, an alkyl substituted silanylene group or an alkyl substituted silaalkylene group; each "X" independently is a halogen, hydride, alkyl, aryl or chelating group, and "y" is an integer of 2 to 4.

Abstract: Disclosed is a process for preparing high molecular weight ethylene-.alpha.-olefin elastomers, preferably an ethylene-propylene elastomer, by liquid phase polymerization of the requisite monomers in the presence of a metallocene/alumoxane catalyst system. Preferably, the process is carried out as a slurry polymerization utilizing the metallocene/alumoxane catalyst in supported form on a silica gel support with the .alpha.-olefin monomer maintained in liquid state and used in excess to serve as a polymerization diluent. The metallocene component of the catalyst by which the process is practiced is of the formula: ##STR1## wherein M is zirconium, titanium or hafnium; each R.sup.1 independently is a C.sub.1 -C.sub.20 linear, branched or cyclic alkyl group or a C.sub.2 -C.sub.4 cyclic alkylene group which forms a fused ring system group; R.sup.2 is a C.sub.1 -C.sub.6 linear, branched or cyclic alkylene, a Si.sub.1 -Si.sub.

Abstract: Disclosed is a process for preparing high molecular weight ethylene-.alpha.-olefin elastomers, preferably an ethylene-propylene elastomer, by liquid phase polymerization of the requisite monomers in the presence of a metallocene/alumoxane catalyst system. Preferably, the process is carried out as a slurry polymerization utilizing the metallocene/alumoxane catalyst in supported form on a silica gel support with the .alpha.-olefin monomer maintained in liquid state and used in excess to serve as a polymerization diluent. The metallocene component of the catalyst by which the process is practiced is of the formula: ##STR1## wherein M is zirconium, titanium or hafnium; each R.sup.1 independently is a C.sub.1 -C.sub.20 linear, branched or cyclic alkyl group or a C.sub.2 -C.sub.4 cyclic alkylene group which forms a fused ring system group; R.sup.2 is a C.sub.1 -C.sub.6 linear, branched or cyclic alkylene, a Si.sub.1 -Si.sub.