Abstract: Polymerization of ethylene using a transition metal hydrocarbyl complex, especially zirconium tetrabenzyl, supported on alumina consisting of substantially spherical particles having diameters in the range 20-150 .mu.m. The particulate polymer produced by the process contains substantially no "fines" (i.e. particles <100 .mu.m diameter) and has improved pourability.

Abstract: Transition metal compositions which are the products of reacting a transition metal complex of the formula RmMXp with a substantially inert matrix material having a hydroxylic surface which is free from adsorbed water, wherein M is a transition metal of Groups IVA to VIA, R is a hydrocarbon group, X is a monovalent ligand and m and p are integers, m having a value from 2 to the highest valency of the metal M and p having a value of from 0 to 2 less than the valency of the metal M, except when M is a metal of Group VIA, when p is 0. When present, ligand X is preferably halogen. The compositions are useful as initiators, particularly for the polymerization of olefinically unsaturated monomers, for example ethylene and propylene.

Abstract: A process for the preparation of an amorphous, vulcanizable, elastomeric copolymer by copolymerization of ethylene and at least one .alpha.-olefin having from 3 to 10 carbon atoms e.g. propylene and optionally in the presence of at least one non-conjugated diene, using as catalyst a transition metal composition which is the product of reacting a transition metal complex of the general formulaR.sub.m MX.sub.p (1)with a substantially inert matrix material having a hydroxylic surface which is free from adsorbed water, where M is a transition metal of Groups IVA to VIA of the Periodic Table of the Elements, R is a hydrocarbon group or substituted hydrocarbon group, X is a monovalent ligand and m and p are integers, m having a value from 2 to the highest valency of the metal M, and p having a value from 0 to 2 less than the valency of the metal M, the copolymerization being effected in a diluent comprising the .alpha.-olefin or mixture of .alpha.