Abstract: A process is provided for extruding a bimodal polyethylene resin. The process includes providing a polyethylene homopolymer or copolymer resin having a bimodal molecular weight distribution; conveying the resin through an extruder having a feed zone in which the resin is not melted, a melt-mixing zone in which at least a portion of the resin is melted, and a melt zone in which the resin is in a molten state, each zone being partially filled with the resin; and contacting the molten resin in the melt zone with a gas mixture of 8 to 40% by volume O2. The resin can be further pelletized. The oxygen-tailored resin can be used to make polyethylene films having improved bubble stability.

Abstract: Disclosed herein are various processes, including continuous fluidized-bed gas-phase polymerization processes for making a high strength, high density polyethylene copolymer, comprising (including): contacting monomers that include ethylene and optionally at least one non-ethylene monomer with fluidized catalyst particles in a gas phase in the presence of hydrogen gas at an ethylene partial pressure of 100 psi or more and a polymerization temperature of 105° C. or less to produce a polyethylene copolymer having a density of 0.945 g/cc or more and an ESCR Index of 1.0 or more wherein the catalyst particles are prepared at an activation temperature of 700° C. or less, and include silica, chromium, and titanium.

Abstract: A method for controlling a transition from an initial polymerization reaction to a target polymerization reaction in a manner that reduces significantly the amount of off-grade product having excessively low density produced during the transition, including steps of: during the transition, maintaining a first one of a concentration ratio and a feed ratio at an at least substantially constant value while implementing process changes in an effort to bring produced polymer into compliance with a target specification set and monitoring (without controlling) the other one of the concentration ratio and the feed ratio to generate first data; and during the transition, determining from the first data whether polymer having excessively low density is likely to be produced during the transition, and upon determining that polymer having excessively low density is likely to be produced during the transition, maintaining during the remaining portion of the transition the other ratio at a value that is at least substantia

Abstract: An apparatus for feeding a dry particulate solid into a pressurized vessel including: a solids reservoir; a rotating metering disc below the solids reservoir; a non-rotating component adjacent to the metering disc; a surface of contact between the metering disc and the non-rotating component, wherein the surface of contact comprises a low friction material; a drive shaft, a drive motor; a pickup section; and an injection tube is provided.

Abstract: A method for selecting a semi-conductive coating to be applied to at least a portion of an inner surface of a polyolefin reaction system wherein the coating has certain electrical properties and a fluidized bed reactor vessel wherein at least a portion of a reactor internal surface is coated with a semi-conductive coating is provided.

Abstract: The invention generally provides for methods for controlling polymer properties. In particular, invention provides for methods for controlling the comonomer composition distribution of polyolefins such as ethylene alpha-olefin copolymers by altering at least one or more of the following parameters: the molar ratio of hydrogen to ethylene, the molar ratio of comonomer to ethylene, the partial pressure of ethylene, and the reactor temperature without substantially changing the density and/or the melt index of the copolymer.

Abstract: In some embodiments, a method including the steps of monitoring a polymerization reaction which produces a polymer resin in a fluid bed reactor, where a dry melt reference temperature is characteristic of melting behavior of a dry version of the resin, and in response to data indicative of at least one monitored parameter of the reaction, determining in on-line fashion a reduced melt reference temperature that is at least substantially equal to the difference between the dry melt reference temperature and a temperature by which the dry melt reference temperature is depressed by the presence of condensable diluent gas with the resin in the reactor. Optionally, the method also includes the step of controlling the reaction in response to the reduced melt reference temperature or a stickiness parameter determined from the reduced melt reference temperature.

Abstract: Embodiments of the present invention include a method of polymerizing olefins comprising contacting olefins with a catalyst composition made by the process of combining a hindered polyalicyclic alkyl catalyst precursor with a particulate inorganic oxide for a deposition time greater than 2 hours to form a catalyst composition. Embodiments of the present invention also include catalyst compositions comprising a hindered polyalicyclic alkyl catalyst precursor made by the process of combining the hindered polyalicyclic alkyl catalyst precursor with a particulate inorganic oxide for a deposition time greater than 2 hours to form the catalyst composition.

Abstract: Bimodal polyethylene compositions and methods for making the same are provided. In at least one specific embodiment, the bimodal polyethylene composition can include a high molecular weight component having a weight average molecular weight (Mw) of from about 400,000 to about 950,000. The bimodal polyethylene composition can also include a low molecular weight component having a weight average molecular weight (Mw) of from about 3,000 to about 100,000. The high molecular weight component can be present in an amount ranging from about 25 wt % to about 40 wt % of the bimodal polyethylene composition. The bimodal polyethylene composition can also have a percent die swell of less than about 80%.

Abstract: A catalyst composition and method for olefin polymerization are provided. In one aspect, the catalyst composition is represented by the formula ?a?b?gMXn wherein M is a metal; X is a halogenated aryloxy group; ? and ? are groups that each comprise at least one Group 15 atom; ? is a linking moiety that forms a chemical bond to each of ? and ?; and a, b, g, and n are each integers from 1 to 4.

Abstract: A process for increasing a granular particle density of a polymeric product using at least one particle density promoting agent is described. The process includes passing a gaseous stream comprising at least one monomer through a fluidized bed reactor in the presence of a catalyst to form a polymeric product having a first granular particle density of less than or equal to about 850 kg/m3, contacting the polymeric product with at least one particle density promoting agent to increase the granular particle density of the polymeric product by at least 2%, withdrawing the polymeric product having an increased granular particle density and a recycle stream comprised of unreacted monomers, and cooling and reintroducing the recycle stream into the fluidized bed reactor with sufficient additional monomer to replace the monomer polymerized and withdrawn as the polymeric product.

Abstract: Various methods and systems for using oxygen in a polyolefin polymerization reactor system are provided. In certain embodiments, the methods are performed in conjunction with a polymerization reactor system such as a gas-phase reactor system.

Abstract: The invention relates to a polymerization process, the polymerization process includes contacting a cyclic bridged metallocene catalyst represented by the following formula: LA(A)LBMQn wherein A is a divalent group bound to each of LA and LB; each of LA and LB are bound to M, and each Q is bound to M; LA and LB are independently selected from the group consisting of cyclopentadienyl ligands and substituted cyclopentadienyl ligands; A is a divalent bridging group comprising a heterocyclic ring comprising from 3 to 6 carbon atoms and one silyl, thus forming a 4 to 7 member divalent ring; M is a Group 4, 5, or 6 transition metal; Q is independently a halogen, a hydride, or a hydrocarbyl radical having from 1 to 20 carbon atoms; wherein n is 1 or 2; with an activator, and optionally a support, to form an activated catalyst and, subsequently, contacting the activated catalyst with ethylene and optionally, at least one C3-C8 alpha olefin comonomer.

Abstract: A method of treating a gas phase fluidized bed reactor and a method of polymerizing olefins in a gas phase fluidized bed reactor in the presence of a catalyst prone to cause sheeting by introducing a chromium-containing compound into the reactor and forming a high molecular weight polymer coating on the walls of the reactor. Furthermore, a device for and method of introducing the chromium-containing compound into the fluidized bed reactor at a plurality of locations in proximity to a lower section of a bed section wall of the fluidized bed reactor, and forming a high molecular weight polymer coating on the bed section wall.

Abstract: In some embodiments, a method including the steps of monitoring a polymerization reaction which produces a polymer resin in a fluid bed reactor, where a dry melt reference temperature is characteristic of melting behavior of a dry version of the resin, and in response to data indicative of at least one monitored parameter of the reaction, determining a reduced melt reference temperature that is at least substantially equal to the difference between the dry melt reference temperature and a temperature by which the dry melt reference temperature is depressed by the presence of condensable diluent gas with the resin in the reactor. Optionally, the method also includes the step of controlling the reaction in response to the reduced melt reference temperature or a stickiness parameter determined from the reduced melt reference temperature.

Abstract: A method of polymerizing olefins with catalyst systems, such as, for example, a multimodal catalyst system, wherein the catalyst system is stored at a controlled temperature to minimize loss of catalyst system productivity.

Abstract: Embodiments of our invention relate generally to methods of monitoring and controlling polymerization reactions including reactions producing multimodal polymer products using multiple catalysts in a single reactor. Embodiments of the invention provide methods of rapidly monitoring and controlling polymerization reactions without the need to sample and test the polymer properties. The method uses reactor control data and material inventory data in a mathematical leading indicator function to control the reactor conditions, and thereby the products produced under those conditions.

Abstract: A method for preparing a spray dried catalyst and a low viscosity, low foam spray dried catalyst system for olefin polymerization are provided. In one aspect, the method includes preparing a catalyst system including one or more components selected from metallocenes, non-metallocenes, and activators, adding mineral oil to the catalyst system to form a slurry, and adding one or more liquid alkanes having three or more carbon atoms to the slurry in an amount sufficient to reduce foaming and viscosity of the slurry. In one aspect, the catalyst system includes one or more catalysts selected from metallocenes, non-metallocenes, and a combination thereof, wherein the catalyst system is spray dried. The system further includes mineral oil to form a slurry including a catalyst system, and one or more liquid alkanes having three or more carbon atoms in an amount sufficient to reduce foaming and viscosity of the slurry.

Abstract: The present invention is directed to the use of aluminum alkyl activators and co-catalysts to improve the performance of chromium-based catalysts. The aluminum alkyls allow for the variable control of polymer molecular weight, control of side branching while possessing desirable productivities, and may be applied to the catalyst directly or separately to the reactor. Adding the alkyl aluminum compound directly to the reactor (in-situ) eliminates induction times.

Abstract: Embodiments of our invention relate to processes for transitioning among polymerization catalyst systems including processes for transitioning among olefin polymerization reactions using Ziegler-Natta catalysts systems and chromium-based catalyst systems. Among embodiments contemplated are a method of transitioning from a first catalyst to a second catalyst in an olefin polymerization reactor, comprising: adding to the reactor a deactivating agent (DA) selected from one of carbon monoxide, carbon dioxide, or combinations thereof; adding to the reactor a cocatalyst adsorbing agent (CAA), comprising an inorganic oxide selected from one of silica, alumina or combinations thereof; wherein the first catalyst comprises at least one conventional Ziegler-Natta catalyst, and a cocatalyst, wherein the second catalyst comprises at least one chromium-based catalyst, wherein the reactor is a gas-phase, fluidized bed reactor, and wherein the CAA is substantially free of transition metals.