Abstract: The present invention is concerned with a process for polymerizing ethylene or copolymerizing ethylene and at least one alpha-olefin comonomer in the presence of a supported polymerization catalyst in a multi-stage process in which the last polymerization stage is a gas phase reactor, the use of said process for reducing particle carry-over in the last polymerization stage and the use of a supported polymerization catalyst with a certain median particle size to polymerize an ethylene homo- or copolymer in said multi-stage process with a span of its particle size distribution which can be predicted from the median particle size of the catalyst.

Abstract: Disclosed are a high melt index thermoplastic elastomer and a preparation method therefor. In the present invention, an emulsion polymerization system and a reversible addition chain transfer free radical polymerization technique are used, and a thermoplastic elastomer having a block structure with a high melt index is obtained by means of controlling reaction temperatures of different stages. The present invention is simple in terms of workflow and equipment and energy-saving and environmentally friendly in terms of process, and the raw materials thereof are cheap and easy to obtain, and the resulting high melt index thermoplastic elastomer has an excellent hot workability.

Abstract: The present invention relates to an olefin-based copolymer of which soluble fraction at a low temperature has a high weight average molecular weight, and which has high flowability and improved physical properties of hardness, flexural strength, tearing strength, etc., and a method for preparing the same.

Abstract: The present invention relates to a method for preparing a conjugated diene-based polymer, which includes a step of preparing a conjugated diene-based polymer by initiating and carrying out polymerization while continuously adding conjugated diene-based monomers to a reactor, and in which an emulsifier is dividedly added before the initiation of the polymerization and when a polymerization conversion rate of 31% to 80% is reached. More particularly, the present invention relates to: a method for preparing a conjugated diene-based polymer and a method for preparing a graft copolymer including the method for preparing a conjugated diene-based polymer, by which a total usage amount of an emulsifier can be reduced.

Abstract: The present invention relates to methods of forming star polymers having configurable architecture in which arms are synthesized by means of living anionic polymerization, with the arms being conjugated with a core, the core comprising m coupling groups, each coupling group having n methylene groups. The invention further relates to star polymers produced therefrom.

Abstract: Methods for preparing metallocene-based catalyst compositions include the steps of contacting an alcohol compound and an organoaluminum compound for a first period of time to form a precontacted mixture, and contacting the precontacted mixture with an activator-support and a metallocene compound for a second period of time to form the catalyst composition. Such catalyst compositions can contain an activator-support, a metallocene compound, an organoaluminum compound, and a dialkyl aluminum alkoxide, and these catalyst compositions have increased catalytic activity for the polymerization of olefins.

Abstract: The present invention provides a post-treatment method of a vinyl chloride-based polymer including: (a) preparing a stream containing vinyl chloride-based polymer powder and unreacted vinyl chloride-based monomers by drying a vinyl chloride-based polymer latex in a drying unit; (b) filtering the stream containing the vinyl chloride-based polymer powder and the unreacted vinyl chloride-based monomers in a filtering unit; and (c) recirculating a gas containing the unreacted vinyl chloride-based monomers discharged from the filtering unit to a latex storage unit.

Abstract: The present invention provides a polymer replica of a target molecule, the polymer replica being capable of accurately inheriting surface information possessed by the target molecule in a molecular imprinting technique.

Abstract: The present disclosure relates to a process and/or method for producing a polymer dispersion by free-radically initiated emulsion polymerization of radically polymerizable ethylenically unsaturated monomers within a polymerization reactor. The polymer dispersion obtained is transferred to a post-treatment reactor and is post-treated therein. The polymer dispersion within the post-treatment reactor is conveyed, simultaneously to the post-treatment, to a circuit for filtration and analysis and is then subsequently fed back into the post-treatment reactor.

Abstract: Sulfated bentonite compositions are characterized by a total pore volume from 0.4 to 1 mL/g, a total BET surface area from 200 to 400 m2/g, and an average pore diameter from 55 to 100 Angstroms. The sulfated bentonite compositions also can be characterized by a d50 average particle size in a range from 15 to 50 ?m and a ratio of d90/d10 from 3 to 15. The sulfated bentonite compositions can contain a sulfated bentonite and from 10 to 90 wt. % of colloidal particles, or the sulfated bentonite compositions can contain a sulfated bentonite and from 0.2 to 10 mmol/g of zinc and/or phosphorus. These compositions can be utilized in metallocene catalyst systems to produce ethylene based polymers.

Abstract: An iodine compound represented by formula (3) and a polymerization inhibitor including the iodine compound, wherein R21 to R25 are as defined herein, X1 is an n1-valent group, and n1 is an integer of 1 to 10:

Abstract: To provide a piezoelectric body film that can suppress decrease in the piezoelectric constant d31, a method of producing a piezoelectric body film, and a piezoelectric body device. A piezoelectric body film comprising a fluororesin as a piezoelectric material, the fluororesin containing, as a main constituent unit, a repeating unit derived from vinylidene fluoride, a piezoelectric constant d31 of the piezoelectric body film being 20 pC/N or greater, and an extrapolated onset temperature at start of shrinkage determined by TMA measurement being not lower than 90° C. and not higher than 115° C. The difference between piezoelectric constants d31 measured before and after heating the piezoelectric body film at 100° C. for 24 hours relative to the piezoelectric constant d31 before the heating for 24 hours is 20% or less.

Abstract: Disclosed are metallocene compounds, catalyst compositions comprising at least one metallocene compound, processes for polymerizing olefins, methods for making catalyst compositions, olefin polymers and articles made from olefin polymers. In an aspect, a metallocene compound and catalyst composition are disclosed in which the metallocene contains at least one indenyl ligand, the indenyl ligand containing at least one halogenated substituent, such as a fluorinated substituent. These metallocene compounds and catalyst compositions can produce polyethylene having unexpectedly low levels of short chain branching.

Abstract: The present disclosure relates to a method of preparing an organic zinc catalyst through solid phase blending that does not require a solvent and a washing process, and a method of preparing a polyalkylene carbonate resin by using the organic zinc catalyst prepared thereby.

Abstract: Proposed is a precursor composition for forming a metal film including a zirconium compound represented by any one of Chemical Formulas 1 to 3 and a hafnium compound represented by any one of Chemical Formulas 4 to 6.

Abstract: Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.

Abstract: A polyethylene homopolymer composition comprises: a first ethylene homopolymer having a density, d1 of from 0.930 to 0.975 g/cm3, a melt index, I21 of from 0.01 to 10 g/10 min, and a molecular weight distribution, Mw/Mn of less than 2.5; and a second ethylene homopolymer having a density, d2 of from 0.945 to 0.980 g/cm3, a melt index, I22 of at least 1.0 g/10 min, and a molecular weight distribution, Mw/Mn of less than 2.5; wherein melt index, I22 of the second ethylene homopolymer is greater than the melt index, I21 of the first ethylene homopolymer. The polyethylene homopolymer compositions which may be nucleated have a weight average molecular weight, Mw of ?75,000, a molecular weight distribution, Mw/Mn of less than 4.0 and may be usefully employed in molding applications, such as, for example, in compression molded closures.

Abstract: An organometallic complex, a catalyst composition employing the same, and a method for preparing polyolefin are provided. The organometallic compound has a structure represented by Formula (I) wherein M is Ti, Zr, or Hf; X is —O—, or —NR6—; R1 and R2 are independently hydrogen, C1-6 alkyl group, C6-12 aryl group, or R1 and R2 are combined with the carbon atoms, to which they are attached, to form an C6-12 aryl moiety; R3, R4 and R5 are independently fluoride, chloride, bromide, C1-6 alkyl group, C6-12 aryl group, C3-6 hetero aryl group, C7-13 aryl alkyl group or C7-12 alkyl aryl group; and R6 is hydrogen, C6-12 aryl group or C7-12 alkyl aryl group.

Abstract: To provide a piezoelectric body film that can suppress decrease in the piezoelectric constant d31, a method of producing a piezoelectric body film, and a piezoelectric body device. A piezoelectric body film comprising a fluororesin as a piezoelectric material, the fluororesin containing, as a main constituent unit, a repeating unit derived from vinylidene fluoride, a piezoelectric constant d31 of the piezoelectric body film being 20 pC/N or greater, and an extrapolated onset temperature at start of shrinkage determined by TMA measurement being not lower than 90° C. and not higher than 115° C. The difference between piezoelectric constants d31 measured before and after heating the piezoelectric body film at 100° C. for 24 hours relative to the piezoelectric constant d31 before the heating for 24 hours is 20% or less.

Abstract: A polyethylene homopolymer composition comprises: a first ethylene homopolymer having a density, d1 of from 0.943 to 0.975 g/cm3, a melt index, I21 of from 0.01 to 10 g/10 min, and a molecular weight distribution, Mw/Mn of less than 3.0; and a second ethylene homopolymer having a density, d2 of from 0.950 to 0.985 g/cm3, a melt index, I22 of at least 500 g/10 min, and a molecular weight distribution, Mw/Mn of less than 3.0; wherein the ratio of the melt index, I22 of the second ethylene homopolymer to the melt index, I21 of the first ethylene homopolymer is at least 50. The polyethylene homopolymer compositions which may be nucleated have a weight average molecular weight, Mw of ?75,000, a high load melt index, I21 of at least 200 g/10 min, a molecular weight distribution, Mw/Mn of from 4.0 to 12.0 and may be usefully employed in molding applications, such as, for example, in compression molded closures.