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: Fibrils of thermoplastic polymer, particularly crystalline thermoplastic polymers such as polyethylene and polypropylene, are prepared by forcing a dispersion of heat softened polymer particles in a liquid medium through a pair of opposed co-axial orifices. The liquid medium is preferably aqueous and is pressurized to prevent boiling. The resulting fibrils have some degree of molecular orientation, and may be useful in the production of reinforced paper.

Abstract: Organometallic compounds of the general formula L.sub.r M(CH.sub.2 SiR.sup.1 R.sup.2 R.sup.3).sub.m (1) where M is a transition metal of Groups IIIA to VIA of the Periodic Table of Elements, m is an integer from 1 to the prevailing valency of the metal M, L.sub.r represents the sum of any other incidental ligands attached to the metal M, r being 0 or an integer, and R.sup.1, R.sup.2 and R.sup.3 represent substituted or unsubstituted hydrocarbyl groups or hydrogen atoms, at least one of said groups having the general formula ##SPC1##Where n is an integer from 1 to 5 and Y is a group capable of donating electrons to the metal M are useful as catalysts for olefin polymerization. The compounds may be used as catalysts alone or when supported upon a matrix for example of alumina. Particularly useful compounds are those in which the transition metal M has a valency lower than the maximum valency for that metal.

Abstract: a copolymer of ethylene with at least one other mono-.alpha.-olefine is prepared and is characterized as having a density in the range 918 to 940 Kg/m.sup.3, an apparent viscosity (A) at 200.degree. C and a shear rate of 100 sec.sup.1 of 0.5 .times. 10.sup.3 to 3.0 .times. 10.sup.3 Nsm.sup.2 and a viscosity at 200.degree. C and a stress of 10.sup.3 N/m.sup.2 of 2 Ae.sup.(1.6A 10 ) to 10,000 A.The copolymer from which the film is formed is preferably one in which the comonomer contains at least 5 carbon atoms; the comonomer may contain up to 12 carbon atoms. Hexene-1 is the preferred comonomer and can be present in the copolymer in an amount of 6.5 to 16.5%, by weight.The copolymers are readily processed and can be formed into films which combine good stiffness and good impact properties.The copolymers are conveniently prepared using supported transition metal benzyl compounds followed by a total work-up of the polymerization mixture.

Abstract: a process for the separation of diluent from an ethylene polymerization reaction mixture wherein ethylene is copolymerized using as a catalyst an organo-metallic compound supported on an inorganic material. Subsequent to reaction, there is added to the reaction mixture a wetting agent and the diluent is then removed from the reaction mixture by steam distillation to give a product having significant solubility in the diluent.A wide variety of wetting agents may be used, which may be either water-soluble or water-insoluble. However, water soluble wetting agents are much preferred, so that most or at least some of the wetting agent remains in the aqueous phase at the end of the steam distillation step. The wetting agent may also possess hydrocarbon solubility; but this does not appear to be of paramount importance. It should also be stable at the steam distillation temperature and should have low steam volatility.

Abstract: a film formed from a copolyme of ethylene and at least one mono-.alpha.-olefine has a combination of impact strength and stiffness which is such that the function ##EQU1## IS AT LEAST 750. The function is preferably at least 1000 and may be several thousands. The film may also have a high tear strength and good tensile strength.The copolymer from which the film is formed is preferably one in which the comonomer contains at least 5 carbon atoms; the comonomer conveniently contains not more than 12 carbon atoms. The comonomer content of the polymer is typically in the range from 6.5 up to 30%, by weight.The film can be produced by a tubular film technique using a temperature of 170.degree.-300.degree. C, a circumferential expansion of 1.2 to 10.0 times and a draw down of 2.5 to 50 times. The production of the polymeric film can include extruding the ethylene copolymer through an annular dye, maintaining the dye temperature in the range from 170.degree.-300.degree.