Abstract: Copolymers of ethylene and ?-olefins having (a) a density (D) in the range 0.900-0.940 g/cm3, (b) a melt index MI2 (2.16 kg, 190° C.) in the range of 0.01-50 g/10 min, (c) a melt index MI2 (2.16 kg, 190° C.) and Dow Rheology Index (DRI) satisfying the equation [DRI/MI2]>2.65, and (d) a Dart Drop Impact (DDI) in g of a blown film having a thickness of 25 ?m produced from the copolymer satisfying the equation DDI?1900×{1?Exp [?750(D?0.908)2]}×{Exp [(0.919?D)/0.0045]}. The copolymers may be prepared using metallocene catalysis and are preferably prepared in multistage processes carried out in loop reactors in the slurry phase. The copolymers exhibit long chain branching as defined by Dow Rheology Index (DRI) and exhibit unexpected improvements in mechanical properties, in particular dart drop impact, when extruded into blown films.

Abstract: A polyethylene composition having a good balance of strength, flexibility and processability is disclosed, comprising (a) 40-55 wt % of a copolymer fraction (A) comprising ethylene and a C4-C10 alpha-olefin, and having an MI2 of from greater than 300 to 800 g/10 min or a Mw of 15 to 35 kDa; and (b) 45-60 wt % of a copolymer fraction (B) comprising ethylene and a C4-C10 alpha-olefin, wherein the composition has an unpigmented density of 940 to 956 kg/m3 and an MI5 of 0.1 to 1 g/10 min.

Abstract: Copolymers of ethylene and ?-olefins are provided having (a) a density (D) in the range 0.900-0.940 g/cm3, (b) a melt index MI2 (2.16 kg, 190° C.) in the range of 0.01-50 g/10 min, (c) a melt index MI2 (2.16 kg, 190° C.) and Dow Rheology Index (DRI) satisfying the equation [DRI/MI2]>2.65, and (d) a Dart Drop Impact (DDI) in g of a blown film having a thickness of 25 ?m produced from the copolymer satisfying the equation DDI?1900×{1?Exp[?750(D?0.908)2]}×{Exp[(0.919?D)/0.0045]}. The copolymers may suitably be prepared by use of metallocene catalysis and are preferably prepared in multistage processes earned out in loop reactors in the slurry phase. The copolymers exhibit long chain branching as defined by Dow Rheology Index (DRI) and exhibit unexpected improvements in mechanical properties, in particular dart drop impact, when extruded into blown films.

Abstract: Transition metal catalysts comprise (a) a source of a Group 3 to 10 transition metal, (b) a ligand having the formula: R1R2X—Y—XR3R4 wherein X is phosphorus, arsenic or antimony, Y is a bridging group having the formula: Z-(A)-D-Rm wherein Z is the moiety linking the X groups, A is a linear or cyclic hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl linking group wherein the number of atoms directly linking Z to D is 1, 2 or 3, D is N, P, As, O, S or Se, R is hydrogen, alkyl, hydrocarbyl, substituted hydrocarbyl, heteroalkyl, heterohydrocarbyl or substituted heterohydrocarbyl, and m is 1 or 2, R1, R2, R3, and R4 are the same or different and represent hydrocarbyl or functionalized hydrocarbyl moieties with the proviso that if D is nitrogen, R is not a cyclic ether, and optionally an activator. The transition metal catalysts are suitable for the selective trimerisation or tetramerisation of olefins in particular ethylene.

Abstract: A method for the preparation of copolymers of ethylene and ?-olefins having a fraction (%) of the molecular weight component of >1,000,000 of less than 6% comprises polymerising ethylene and an ?-olefin in the presence of a supported polymerisation catalyst system comprising (a) a transition metal compound (b) a porous support material, and (c) an activator characterized in that the support material has been (i) dried at a temperature in the range 0° C. to 195° C. in an inert atmosphere, and (ii) treated with an organometallic compound. The resultant supported catalyst systems show improved productivity and allow for control of the resultant polymer properties. Particularly preferred supported catalyst systems are those comprising metallocene complexes.

Abstract: A method for the preparation of copolymers of ethylene and ?-olefins having a fraction (%) of the molecular weight component of >1,000,000 of less than 6% comprises polymerising ethylene and an ?-olefin in the presence of a supported polymerisation catalyst system comprising (a) a transition metal compound (b) a porous support material, and (c) an activator characterized in that the support material has been (i) dried at a temperature in the range 0° C. to 195° C. in an inert atmosphere, and (ii) treated with an organometallic compound. The resultant supported catalyst systems show improved productivity and allow for control of the resultant polymer properties. Particularly preferred supported catalyst systems are those comprising metallocene complexes.