Abstract: A process for producing a propylene copolymer having increased melt strength, the process comprising irradiating a copolymer of propylene and ethylene which has been polymerised using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGray and melting and mechanically processing the melt of the irradiated ethylene propylene copolymer to form long chain branches on the ethylene propylene copolymer molecules.

Abstract: A process for moulding polyolefins having an enhanced crystallisation rate from the melt, the process comprising irradiating one or more polyolefins having a double bond concentration of at least 0.1 per 10,000 carbon atoms with an electron beam having an energy of at least 5 MeV and at a radiation dose of at least 5 kGray, and mechanically processing the irradiated one or more polyolefins in a melt to form long chain branches on the polyolefin molecules, and moulding the melt to form a solid article. A process for moulding polypropylene from the melt, the process comprising irradiating polyropylene which has been polymerised using a metallocene catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 5 kGray, mechanically processing the irradiated polypropylene in a melt to form long chain branches on the polypropylene molecules, and moulding the melt to form a solid article.

Abstract: A process for producing a propylene copolymer having increased melt strength, the process comprising irradiating a copolymer of propylene and ethylene which has been polymerised using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGray and melting and mechanically processing the melt of the irradiated ethylene propylene copolymer to form long chain branches on the ethylene propylene copolymer molecules.

Abstract: A process for producing polypropylene, the process comprising homopolymerising propylene or copolymerising propylene with one or more comonomers selected from ethylene and C4 to C10 1-olefins in the presence of a metallocene catalyst system comprising (a) a metallocene catalyst of general formula R″(XRm)(Cp′R′n)M2, wherein X is a cyclopentadienyl moiety (Cp) or a heteroatom, Cp′ is a substituted or unsubstituted fluorenyl ring; each R is independently hydrogen or hydrocarbyl having 1 to 20 carbon atoms in which O≦m≦4; each R′ is independently hydrocarbyl having 1 to 20 carbon atoms in which 0≦n≦8; R″ is a bridge which comprises a C1-C20 alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphine or amine radical, which bridge is substituted or unsubstituted, M is a Group IVB transition metal, vanadium or a lanthanide metal and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen, and (b) a cocatalyst which activates the catalyst c

Abstract: A process for producing polypropylene having increased melt strength, the process comprising (i) homopolymerising polypropylene or copolymerising propylene with one or more comonomers selected from ethylene and C4 to C101-olefins to produce a polypropylene homopolymer or copolymer respectively having a double bond concentration of at least 0.1 per 10,000 carbon atoms, (11) irradiating the polypropylene with an electron beam having an energy of at least 5 MeV and at radiation dose of at least 5 kGray, and (iii) melting and mechanically processing the melt of polypropylene to form long chain branches on the polypropylene molecules.

Abstract: The present invention concerns a catalyst for the production of high density polyethylene, by homopolymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, prepared by the steps of: a) selecting a silica support with a specific surface area larger than 300 m2/g; b) treating the silica support with a titanium compound, in order to introduce titanium into the support, or with an aluminium compound, in order to introduce aluminium into the support; c) either treating the titanated silica support with an aluminum compound, in order to introduce aluminum into the titanated silica support, or treating the aluminated silica support with a titanium compound, in order to introduce titanium into the aluminated silica support; d) depositing a chromium compound on the titanated and aluminated silica support to form a catalyst; e) activating the catalyst of step d) under air in a fluidised bed at a temperature of from 600 to 800° C.

Abstract: A process for producing a Ziegler-Natta catalyst, the process comprising reacting an organo magnesium compound with a halogenated compound to produce crystalline magnesium halide having an intense diffraction line in an x-ray spectrum thereof at lattice distance within the range of from 2.56 to 3.20 Angstroms and titanating the magnesium halide by mixing the magnesium halide with a titanium compound whereby the titanated magnesium halide hasp in an x-ray spectrum thereof, a halo appearing at a lattice distance within the range from 2.56 to 3.30 Angstroms.

Abstract: A process for the preparation of polyethylene resins having a multimodal molecular weight distribution which comprises: (i) contacting ethylene monomer and a comonomer comprising an alpha-olefin having from 3 to 10 carbon atoms with a first catalyst system in a first reactor under first polymerization conditions to produce a first polyethylene having a first molecular weight, an HLMI of not more than 0.5 g/10 min and a first density of not more than 0.

Abstract: A process for producing ultra fine silica particles, the process comprising directing a plasma jet onto a silicon-containing compound thereby to form silica vapor and condensing the silica vapor on a collection surface.

Abstract: The present invention relates to a supported chromium-based catalyst titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has high shear resirance and environmental stress crack resistance, and can be used for manufacturing films with improved tear properties.

Abstract: A process for the production of a magnesium chloride powder for use in a catalyst, the process comprising vaporising magnesium chloride in a plasma torch and quenching the vapour with a liquid containing an electron donor to form a magnesium chloride-based powder catalyst wherein at least 80% by weight of the magnesium chloride is present as the hexagonal phase thereof. The invention also relates to a precursor for such a catalyst.

Abstract: A process for preparing polyethylene, including contacting ethylene monomer and an alpha-olefin comonomer to produce a first polyethylene (HLMI of ≦0.5 g/10 min, density ≦0.925 g/ml). The a catalyst system is a bis tetrahydroindenyl formula (IndH4)2R″MQ2 wherein each Ind is the same or different and is indenyl or substituted indenyl, R″ is a bridge which comprises a C1-C20 alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphine or amine radical, which bridge is substituted or unsubstituted, M is a Group IVB transition metal or vanadium and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen. The polyethylene resin having multimodal molecular weight distribution is formed by mixing the first polyethylene with a second polyethylene (produced with a different catalyst and with a lower molecular weight and higher density than the first polyethylene).

Abstract: A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1.

Abstract: A process for the preparation of polyethylene resins having a multimodal molecular weight distribution which comprises:

Abstract: A process for producing a polyethylene resin having a monomodal molecular weight distribution in a single polymerisation reactor using a chromium-based catalyst system, by copolymerising ethylene and an alpha-olefinic-comonomer having from 3 to 8 carbon atoms, the polyethylene resin comprising a blend of a higher molecular weight fraction polymerised by a first chromium-based catalyst of the system and a lower molecular weight fraction polymerised by a second chromium-based catalyst of the system, wherein the comonomer incorporation in the higher molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction whereby the higher and lower molecular weight fractions differ in density by from 0.01 to 0.03 g/cc.

Abstract: A process for the production of a magnesium chloride powder for use in a catalyst, the process comprising vaporizing magnesium chloride in a plasma torch and quenching the vapor with a liquid containing an electron donor to form a magnesium chloride-based powder catalyst wherein at least 80% by weight of the magnesium chloride is present as the hexagonal phase thereof. The invention also relates to a precursor for such a catalyst.

Abstract: A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1.

Abstract: A process for producing high density polyethylene suitable for blow molding and having high environmental stress cracking resistance and rigidity copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, in the presence of a chromium-based catalyst, having an alumina-containing support, and an organoboron compound, wherein the atomic ratio of boron in the organoboron compound to the chromium in the chromium-based catalyst is from around 0.2 to around 0.4.

Abstract: A process for the preparation of polyethylene resins having a multimodal molecular weight distribution which comprises:

Abstract: A process for the preparation of polyolefins having a bi- or multimodal molecular weight distribution, the process comprising the steps of: (i) contacting an olefin monomer and a first co-reactant with a catalyst system in a first reaction zone under first polymerization conditions to produce a product comprising a first polyolefin having a first molecular weight distribution; and (ii) contacting an olefin monomer and a second co-reactant with a catalyst system in a second reaction zone under second polymerization conditions to produce a product comprising a second polyolefin having a second molecular weight distribution different from the first molecular weight distribution; wherein the first and second polyolefins are mixed together, wherein one of the co-reactants is hydrogen and the other is a comonomer selected from butene, methylpentene, hexene or octene, and wherein each catalyst system comprises (a) a metallocene catalyst component comprising a bis tetrahydroindenly compound of the general formula (In