Abstract: A process for preparing an ethylene polymer including the step of homopolymerizing ethylene or copolymerizing ethylene with one or more comonomers in a gas-phase polymerization reactor including a riser unit wherein growing polymer particles flow upwards under fluidization, fast fluidization or transport conditions and a downcomer wherein growing polymer particles flow downward in a densified form, wherein the hold-up of polymer particles in the downcomer is from 55 wt. % to 80 wt. % of the total hold-up of polymer particles in the gas-phase polymerization reactor.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.948 to 0.952 g/cm3 determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) Mz equal to or greater than 1,200,000 g/mol; 5) ?0.02 from 35,000 to 55,000 Pa·s; 6) long-chain branching index, LCBI, equal to or greater than 0.55; and 7) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.940 to 0.955 g/cm3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from 12 to 40; 3) Mz from 500,000 to 3,500,000 g/mol; 4) ?0.02 from 80,000 to 300,000 Pa·s; 5) HMWcopo index from 1 to 15; and 6) Mz/Mw*LCBI lower than 6.4.

Abstract: A process for preparing a polyolefin composition including the steps of supplying a bimodal or multimodal polyolefin in form of a polyolefin powder having an mass-median-diameter D50 in the range from 300 ?m to 2500 ?m and one or more additives to a mixing device, mixing the polyolefin powder and the additives at a temperature from 10° C. to 120° C., transferring the mixture into a extruder device, melting and homogenizing the mixture within the extruder device to form a molten polyolefin composition, and pelletizing the molten polyolefin composition.

Abstract: A polyethylene composition having the following features: 1) density from 0.945 to 0.958 g/cm3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from 20 to 43; 3) MIF from 4.0 to less than 8.5 g/10 min.; 4) HMWcopo index from 3.5 to 20; and 5) long-chain branching index, LCBI, equal to or lower than 0.82. The polyethylene composition can be used to produce blown films.

Abstract: A polyethylene composition having the following features: 1) density from about 0.945 to about 0.955 g/cm3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from about 23 to about 40; 3) MIF from about 8.5 to about 18 g/10 min.; 4) HMWcopo index from about 3.5 to about 20; and 5) long-chain branching index, LCBI, equal to or greater than about 0.45. The polyethylene composition can be used to produce pipes and films.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from greater than 0.957 to 0.965 g/cm3, determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) Mw equal to or greater than 230,000 g/mol; 5) ?0.02 from 35,000 to 55,000 Pa·s; 6) long-chain branching index, LCBI, equal to or greater than 0.55; and 7) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from greater than 0.952 to 0.957 g/cm3, determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) ?0.02 from 30,000 to 55,000 Pa·s; 5) long-chain branching index, LCBI, equal to or greater than 0.55; 6) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: A process for starting a multizone circulating reactor containing no polyolefin particles, comprising the steps of conveying gas through the reactor and the gas recycle line, feeding a particulate material comprising a polymerization catalyst and optionally polyolefin into the reactor, controlling the gas flow in a vertical reactor zone equipped with a throttling valve at the bottom so that the upwards gas velocity in the bottom part of this reaction zone is lower than the terminal free-fall velocity of the particulate material fed into the reactor, and, after the weight of the particulate polyolefin in this reactor zone is higher than the drag force of the upward moving gas, controlling the circulation rate of the polymer particles within the multizone circulating reactor by adjusting the opening of the throttling valve and adjusting the flow rate of a dosing gas.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.940 to 0.955 g/cm3 determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from 12 to 30; 3) Mz from 2,000,000 to 4,500,000 g/mol; 4) ?0.02 from 160,000 to 300,000 Pa·s; and 5) long-chain branching index, LCBI, equal to or greater than 0.75.

Abstract: A polyethylene composition having the following features: 1) density from about 0.945 to about 0.951 g/cm3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from about 25 to about 43; 3) MIF from about 3.5 to less than about 8.5 g/10 min.; 4) HMWcopo index from about 1 to about 40; and 5) long-chain branching index, LCBI, equal to or greater than about 0.83. The polyethylene composition can be used to produce pipes.

Abstract: A process for preparing an ethylene polymer including the step of homopolymerizing ethylene or copolymerizing ethylene with one or more comonomers in a gas-phase polymerization reactor including a riser unit wherein growing polymer particles flow upwards under fluidization, fast fluidization or transport conditions and a downcomer wherein growing polymer particles flow downward in a densified form, wherein the hold-up of polymer particles in the downcomer is from 55 wt. % to 80 wt. % of the total hold-up of polymer particles in the gas-phase polymerization reactor.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.948 to 0.952 g/cm3 determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) Mz equal to or greater than 1,200,000 g/mol; 5) ?0.02 from 35,000 to 55,000 Pa·s; 6) long-chain branching index, LCBI, equal to or greater than 0.55; and 7) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: Process for preparing an olefin polymer including the step of polymerizing an olefin in the presence of a polymerization catalyst and hydrogen as molecular weight regulator in a gas-phase polymerization reactor to yield growing polymer particles, the reactor including three or more polymerization zones and at least two thereof are sub-zones of a polymerization unit wherein the growing polymer particles flow downward in a densified form and at least one polymerization zone has a ratio of hydrogen to the sum of olefins which is a factor of at least 1.5 lower than the ratio of hydrogen to the sum of olefins in the polymerization zone having the highest ratio of hydrogen to the sum of olefins and a factor of at least 1.5 higher than the ratio of hydrogen to the sum of olefins in the polymerization zone having the lowest ratio of hydrogen to the sum of olefins.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from greater than 0.957 to 0.965 g/cm3, determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) Mw equal to or greater than 230,000 g/mol; 5) ?0.02 from 35,000 to 55,000 Pa·s; 6) long-chain branching index, LCBI, equal to or greater than 0.55; and 7) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from greater than 0.952 to 0.957 g/cm3, determined according to ISO 1183-1 at 23° C.; 2) ratio MIF/MIP from 12 to 25; 3) MIF from 18 to 40 g/10 min.; 4) ?0.02 from 30,000 to 55,000 Pa·s; 5) long-chain branching index, LCBI, equal to or greater than 0.55; 6) ratio (?0.02/1000)/LCBI from 55 to 75.

Abstract: The present disclosure relates to a continuous process for the preparation of ethylene homopolymers or ethylene copolymers comprising polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a chromium catalyst in a gas-phase polymerization reactor which is equipped with a cycle gas line for withdrawing reactor gas from the reactor, leading the reactor gas through a heat-exchanger for cooling and feeding the reactor gas back to the reactor, wherein the polymerization is carried out at a temperature from 30° C. to 130° C. and a pressure of from 0.1 to 10 MPa and an aliphatic carboxylic acid ester having from 8 to 24 carbon atoms is added.

Abstract: Polyethylene composition for injection molding with a beneficial balance of environmental stress cracking resistance and impact resistance in combination with low warpage and beneficial processing behavior, said composition having the following features: 1) density of 0.945 g/cm3 or higher; 2) MIE from 1 to 30 g/10 min.; 3) ratio MIF/MIE from 15 to 30; 4) ER values from 0.40 to 0.52.

Abstract: A process for the preparation of an ethylene polymer including the step of polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a Phillips-type chromium catalyst in a gas-phase polymerization reactor containing a reactor bed of particulate polymer, wherein the gas-phase polymerization reactor is equipped with a cycle gas line, wherein the reactor gas returned to the polymerization reactor through the cycle gas line has been condensed in part and the amount of liquid in the returned reactor gas is from 0.5 wt. % to 10 wt. % based upon the total weight of the reactor gas/liquid composition, the polymerization is carried out at from 108° C. to 125° C., and an aluminum alkyl is fed into the polymerization reactor in an amount in the range of from 0.0025 mole to 0.1 mole per ton of dosed ethylene.

Abstract: A process for the preparation of polyolefins by polymerizing olefins at temperatures of from 20 to 200° C. and pressures of from 0.1 to 20 MPa in the presence of a polymerization catalyst and an antistatically acting composition in a polymerization reactor, wherein the antistatically acting composition is a mixture comprising an oil-soluble surfactant and water and the use of an antistatically acting composition comprising an oil-soluble surfactant and water as antistatic agent for the polymerization of olefins at temperatures of from 20 to 200° C. and pressures of from 0.1 to 20 MPa in the presence of a polymerization catalyst.