Abstract: The present disclosure generally relates to a slurry polymerization process for the preparation of polyethylene in the presence of a Ziegler catalyst and aluminum alkyl co-catalyst in at least one polymerization reactor, in which process suspension medium comprising a concentration of aluminum alkyl co-catalyst is recycled to the polymerization, the concentration of aluminum alkyl co-catalyst in the recycled suspension medium is determined; and the amount of fresh aluminum alkyl co-catalyst fed to the polymerization is adjusted to maintain a targeted aluminum alkyl co-catalyst concentration in the recycled suspension medium.

Abstract: A process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators, wherein the polymerization is carried out at temperatures from 100° C. to 350° C. and pressures in the range of from 110 MPa to 500 MPa in a continuously operated polymerization reactor which is controlled by a pressure control valve at the outlet of the polymerization reactor, the process comprising continuously monitoring the pressure within the polymerization reactor, feeding a pressure signal to a controller for controlling the control valve and having the controller altering the opening of the pressure control valve to control the pressure within the polymerization reactor, wherein the controller starts an emergency shutdown program when the pressure control valve closes more than a preset threshold value and the pressure within the polymerization reactor decreases below a preset pressure threshold.

Abstract: A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 30 to about 55; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having about the same molecular weight of 1,000,000 g/mol.

Abstract: A slurry polymerization process for the preparation of polyethylene in a reactor cascade of two or more polymerization reactors including the steps of feeding to a polymerization reactor amounts of ethylene, of a Ziegler catalyst, of fresh aluminum alkyl and of a diluent; feeding the slurry product withdrawn from the polymerization reactor to a second polymerization reactor; and feeding additional amounts of ethylene and of diluent wherein the ethylene is first passed through an ethylene purification unit, which reduces at least the concentration of carbon monoxide, carbon dioxide, oxygen, acetylene and water contained in the ethylene, before it is fed to the two or more polymerization reactors of the reactor cascade.

Abstract: A process for the gas-phase polymerization of ethylene or a mixture of ethylene and one or more 1 olefins in the presence of a polymerization catalyst system comprising the steps a) feeding a solid catalyst component, which was obtained by contacting at least a magnesium compound and a titanium compound, to a continuously operated apparatus and contacting the solid catalyst component with an aluminum alkyl compound at a temperature of from 0° C. to 70° C. in a way that the mean residence time of the solid catalyst component in contact with the aluminum alkyl compound is from 5 to 300 minutes; b) transferring the catalyst component formed in step a) into another continuously operated apparatus and prepolymerizing it with ethylene or a mixture of ethylene and one or more 1 olefins in suspension at a temperature of from 10° C. to 80° forming polymer in an amount of from 0.

Abstract: The present disclosure relates to an ethylene polymer composition having an eta (0.01) equal to or higher than 35,000 Pa·s, comprising: A) 25-75% by weight of an ethylene polymer selected from ethylene homopolymers, copolymers of ethylene with 10% or less of one or more olefin comonomers, and mixtures of the homopolymers and copolymers; B) 25-75% by weight of a copolymer of ethylene and propylene comprising 45-70% by weight of ethylene; wherein eta (0.01) is the complex shear viscosity at an angular frequency of 0.01 rad/s, measured with dynamic oscillatory shear in a plate-plate rotational rheometer at a temperature of 200° C., and the amounts of A) and B) refer to the total weight of A)+B).

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.

Abstract: A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 30 to about 55; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having about the same molecular weight of 1,000,000 g/mol.

Abstract: A process for separating polymeric and gaseous components of a polymer-monomer mixture at a pressure of from 0.12 MPa to 0.6 MPa and a temperature of from 120° C. to 300° C. in a separation vessel is provided. The separation vessel has a vertically arranged cylindrical shape with a ratio of length to diameter L/D of from 0.6 to 10 and an inlet pipe capable of introducing the polymer-monomer mixture into the separation vessel which the inlet pipe extends vertically from the top of the separation vessel into the separation vessel. Further a process for preparing ethylene homopolymers or copolymers from ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at temperatures from 100° C. to 350° C. and pressures in the range of from 110 MPa to 500 MPa comprising such a process for separating a polymer-monomer mixture is provided.

Abstract: A process for continuously preparing a polyolefin composition made from or containing a polyolefin and carbon black in an extruder device. The process includes the steps of supplying polyolefin in form of a polyolefin powder and carbon black to a mixing device; alternatively, (a) measuring the flow rate of the polyolefin powder supplied to the mixing device or (b) measuring the flow rate of the polyolefin pellets prepared in the extruder device; adjusting the flow rate of the carbon black to the mixing device in response to the measured flow rate of the polyolefin powder or adjusting the flow rate of the polyolefin powder to the mixing device in response to the measured flow rate of the polyolefin pellets; melting and homogenizing the mixture within the extruder device; and pelletizing the polyolefin composition into the polyolefin pellets.

Abstract: The present technology relates to a process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators, wherein the polymerization is carried out in a continuously operated tubular reactor at temperatures from 100° C. to 350° C. and pressures from 180 MPa to 340 MPa, with a specific reactor surface area Asp of 2 m2/(t/h) to 5.5 m2/(t/h), and the tubular reactor has a specific ratio RDsp of 0.0050 MPa?1 to 0.0069 MPa?1 and an inner surface which has a surface roughness Ra of 2 ?m or less.

Abstract: A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 10 to less than about 30; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having the about same molecular weight of 1,000,000 g/mol.

Abstract: Polyethylene composition with improved balance of impact resistance at low temperatures and Environmental Stress Cracking Resistance (ESCR), particularly suited for producing protective coatings on metal pipes, said composition having the following features: 1) density from 0.938 to 0.948 g/cm3; 2) ratio MIF/MIP from 15 to 25; 3) MIF from 30 to 45 g/10 min.; 4) Mz equal to or greater than 1000000 g/mol; 5) LCBI equal to or greater than 0.55.

Abstract: A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C3 to C10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29° C. or higher.

Abstract: A method for controlling a slurry polymerization for the preparation of polyethylene, where the polyethylene is formed in a polymerization reactor comprising a vapor section by contacting a Ziegler-type catalyst, ethylene, and either hydrogen or, as comonomer(s), one or more C3 to C10 alpha-olefins or hydrogen and one or more C3 to C10 alpha-olefins, wherein the ethylene partial pressure is maintained by adjusting the flow rate of the catalyst to the polymerization reactor and the hydrogen/ethylene and comonomer/ethylene partial pressure ratios are maintained by adjusting the flow rates of hydrogen and/or of the one or more comonomers to the polymerization reactor.

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.

Abstract: A process for continuously preparing a polyolefin composition made from or containing a bimodal or multimodal polyolefin and one or more additives in an extruder device equipped with at least one hopper. The process includes the steps of supplying a bimodal or multimodal polyolefin in form of a polyolefin powder to the hopper; (a) measuring the flow rate of the polyolefin powder or (b) measuring the flow rate of the prepared polyolefin pellets; supplying one or more additives to the hopper; adjusting the flow rates of the additives supplied to the hopper in response to the measured flow rate of the polyolefin powder or adjusting the flow rate of the polyolefin powder in response to the measured flow rate of the polyolefin pellets; melting and homogenizing the polyolefin powder and additives within the extruder device; and pelletizing the molten polyolefin composition into the polyolefin pellets.

Abstract: The present technology relates to a process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators, wherein the polymerization is carried out in a continuously operated tubular reactor at temperatures from 100° C. to 350° C. and pressures from 180 MPa to 340 MPa, with a specific reactor surface area Asp of 2 m2/(t/h) to 5.5 m2/(t/h), and the tubular reactor has a specific ratio RDsp of 0.0050 MPa?1 to 0.0069 MPa?1 and an inner surface which has a surface roughness Ra of 2 ?m or less.

Abstract: The present disclosure relates to a polyethylene composition with improved swell ratio and mechanical properties for use in preparing blow-molded articles and having the following features: 1) a density from 0.945 to less than 0.952 g/cm3; 2) an MIF/MIP ratio from 15 to 30; 3) a Shear-Induced Crystallization Index (SIC) from 2.5 to 5.5.

Abstract: A two steps polymerization process for obtaining a polyolefin composition comprising: a) from 25 wt % to 70 wt % of a propylene homopolymer or a propylene-ethylene copolymer containing from 0.1 wt % to 10 wt % of ethylene derived units; b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least one C3-C20 alpha olefins, wherein the ethylene derived units content ranges from 15 wt % to 70 wt %; c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene and at least one C3-C20 alpha olefins copolymer; the sum a)+b)+c) being 100, wherein said process comprises: step a) contacting under polymerization conditions propylene, optionally ethylene and the catalyst system in order to obtain component a), step b) contacting under polymerization conditions ethylene and at least one C3-C20 alpha-olefins and the catalyst system in order to obtain components b) and c); wherein the catalyst system comprises a metallocene compound and an iron complex.