Abstract: A high molecular weight copolymer of ethylene and a C.sub.3 -C.sub.20 .alpha.-olefin which, after being molded at room temperature and pressure-free tempered at 120 to 250.degree. C. and thereafter cooled, provides molded articles having an ultimate tensile strength of more than 200 kg per square centimeter measured at 120.degree. C. and an impact strength of more than 200 kg cm/cm.sup.2 measured at 23.degree. C.; a process for the preparation of such a copolymer by a Ziegler catalysis which process is characterized in that the catalyst which is employed is one obtained by reducing a titanium-(IV)-halide with an organo-aluminum compound in an inert solvent such that the concentration of titanium-(III)-halide so formed amounts to 30 to 200 m mol/liter solvent, the C.sub.3 -C.sub.20 .alpha.-olefin is employed in an amount of 0.05 to 5 weight percent based upon the weight of the ethylene and the catalyst is either initially contacted with C.sub.3 -C.sub.20 .alpha.

Abstract: Aluminum cyclopentadienyl compounds can be used to synthesize a variety of organic molecules containing the cyclopentadiene group, e.g., substituted cyclopentadiene compounds, polymer molecules with cyclopentadiene pendant groups, and polymer molecules with cyclopentadiene terminal groups.

Abstract: An improved polyvinyl halide or a vinyl halide copolymer containing up to 50 percent of a comonomer can be obtained by post polymerizing in a single stage or two-stage bulk process in contact with a base polymer, the same or different monomer as the monomer used to form the base polymer. Compositions produced by the process of the invention are useful in making films, coated fabrics and molded objects. The liquid phase post polymerization process of the invention is applicable to base polymers in powder form prepared by emulsion, suspension and bulk polymerization processes. The base polymer can be present in a polymerization mixture in which only a partial amount of monomer has been converted to base polymer such as in a two-stage polymerization process or the base polymer can be used in dry, solid form. Polymers of the invention have improved bulk density and reduced plasticizer uptake and can be used to prepare fabric coatings.

Abstract: Polyethylene is produced by polymerization of ethylene alone or with comonomers and/or telogens (modifiers) in an elongated tubular reactor having an inlet and outlet and preferably containing four reaction zones. Conversions of up to 40% are achieved without loss of optical or physical product quality.

Abstract: Graft polymers are prepared by contacting an anionically polymerizable monomer such as butadiene with a polymer-Li.tertiary chelating polyamine complex such as polystyrene-Li.tetramethyl ethanediamine.

Abstract: Ethylene is polymerised or copolymerised using a transition metal catalyst at a pressure in the range 300-1000 atmospheres and a temperature of at least 100.degree. C in the presence of a volatile inert diluent such as pentane, or at least one 1-olefine comonomer such as buten-1, or both. The catalyst can be a Ziegler type catalyst, an organo-compound of a transition metal such as a substituted silylmethyl, cyclopentadienyl, arene, norbornyl, .pi.-allyl or benzyl compound and may be supported on a suitable support such as silica, alumina, or magnesia. Other catalysts which may be used are supported chromium or molybdenum oxides. If a solid catalyst is used it is preferred to use a material which has been finely dispersed.

Abstract: Vapor phase polymerization of an olefin which comprises conveying inactive high yield titanium catalyst component to a vapor phase polymerization reactor with a liquid comprising recycled quench liquid, reactivating said inactive high yield titanium catalyst component inside the reactor with a metal alkyl reducing agent and polymerizing olefin under gas phase polymerization conditions with reactivated high yield catalyst to form a resinous polymer of an olefin having a low level of catalyst residues.

Abstract: Low density polyethylene with a very small proportion of low molecular weight polyethylene (e.g. such as can be extracted by washing by ethanol) is used as an insulation material for high voltage power cable.

Abstract: Apparatus and process is herein disclosed by which a polymerizable monomer or mixture thereof can be economically and efficiently converted to polymeric substances with a high yield catalyst and, optionally, co-catalyst by a vapor phase, essentially isobaric, polymerization process using a horizontal, stirred-bed, quench-cooled, essentially total reactor off-gas recycle reactor.

Abstract: Peroxide cross-linked polymeric compositions containing brominated flame retardants have reduced water absorption if an unsaturated co-agent is used to reduce the amount of peroxide needed to effect cross-linking. This makes it possible to replace part or all of the chlorinated flame retardants conventionally used and yet to obtain cross-linked compositions which meet the IPCEA water absorption requirements and can therefore be used for insulating electrical wire and cable.

Abstract: In producing a low density polyethylene by copolymerization in slurry state of ethylene and an .alpha.-olefin with use of a catalyst consisting of a supported titanium component and an organoaluminum compound, a certain amount of ethylene is subject to pre-polymerization in the presence of said catalyst prior to the copolymerization. Successively, the copolymerization of ethylene and an .alpha.-olefin is effected in a two-step process, in which a copolymerization ratio of .alpha.-olefin to ethylene is kept at a low level in the first step and raised to a high level in the second step thereby to obtain a low density polyethylene having a density of not higher than 0.945 g/cm.sup.3.

Abstract: An improved process for preparing an impact-resistant chemically blended propylene polymer or copolymer, which comprises the following three steps:(1) a first step of polymerizing propylene containing 0 to 1 mole% of another olefin in the presence of a catalyst composed of (a) a carrier-supported titanium catalyst component containing at least magnesium, halogen and titanium on the surface of the carrier and (b) an organo aluminum compound to form specific crystalline polypropylene;(2) a second step of copolymerizing propylene and ethylene in the presence of the reaction product of the first step and the same catalyst while maintaining the content of propylene in the gaseous phase of the polymerization zone at 65 to 90 mole% thereby to form specific low-crystalline propylene/ethylene copolymer; and(3) a third step of polymerizing ethlene, or both ethylene and propylene in the presence of the reaction product of the second step and the same catalyst while maintaining the content of propylene in the gaseous pha

Abstract: A process for preparing cis-polyisoprene which comprises polymerization of isoprene in a medium of a non-polar hydrocarbon solvent at a temperature ranging from 0.degree. to 60.degree. C in the presence of a catalyst comprising a reaction product of titanium tetrachloride and an intracyclic organo-aluminium compound having the formula: ##STR1## wherein R, the same or different, are H, CH.sub.3 ; taken in a molar ratio of 1:1.05-1.1 respectively; weight ratio of isoprene to said catalyst being equal to 100:0.2-0.7.The present invention makes it possible to improve the quality of the thus-obtained cis-polyisoprene and to increase the catalyst capacity by two times due to modification of its properties.

Abstract: The invention concerns a low-density polyethylene-based polymer composition for producing films or sheaths. The present invention provides a low-density polyethylene-based polymer composition for manufacturing films or sheaths, particularly thin films or sheaths having a thickness of less than twenty microns, said polymer composition being constituted by a graft copolymer comprising at least one styrene monomer, possibly mixed with at least one acrylic monomer, said monomer or monomers being grafted onto a trunk constituted by a pre-formed combination or alloy containing by weight, 50 to 95% low-density polyethylene and 50 to 5% high density polyethylene and/or polypropylene, the proportion of the grafted styrene monomer or mixture of monomers being comprised between 5 and 50% by weight of said graft copolymer.

Abstract: Object of the invention is a process for polymerizing chloroprene in aqueous emulsion in a certain apparatus which prevents formation of deposits and so-called "popcorn" polymers.

Abstract: A continuous process and an apparatus for the polymerization of vinyl chloride in aqueous emulsion wherein the liquid reaction mixture is fed into the lower part of a vertical, cylindrical vessel, the liquid level in the vessel is adjusted to at most 97% of the total interior height of the vessel, the reaction mixture is stirred with a stirrer which is totally immersed in the liquid and extends over 15 to 60% of the total interior height of the vessel and the produced polymer emulsion is laterally discharged from the upper part of the vessel.

Abstract: Electrical insulating compositions consisting of an ethylene/vinyl acetate copolymer containing from 0.5 to 9.5 percent by weight of vinyl acetate units, from 0.1 to 2.0 percent by weight of polymerized 2,2,4-trimethyl-1,2-dihydroquinoline, from 0.5 to 5 percent by weight of a triallyl cyanurate and, optionally, up to 0.1 percent by weight of sulfur. The compositions can be crosslinked, with high yield, by treatment with high energy radiation.

Abstract: There is described a process for the homopolymerization or copolymerization in the bulk of alkenylaromatic compounds in a continuous flow agitation vessel. The feed of the monomer(s) is preheated and a controlled larger or smaller part of the preheated monomer feed is cooled, depending on the deviation of the temperature of the contents of the reaction vessel from the determined value. The inventive process ensures an improved constancy of the reaction temperature, and, consequently, of the molecular weight of the polymer obtained.

Abstract: A process for polymerizing ethylene under the high temperature and high pressure conditions by using a battery of two or more autoclave reactors connected in series by means of piping provided with a heat exchanger, each of said reactors having an upper reaction zone and a lower reaction zone. According to this process, the reaction yield of polyethylene is higher than that attainable from the conventional two-zone polymerization methods, and the obtained polyethylene is improved in optical properties and processability.

Abstract: Apparatus is provided to feed controlled quantities of a catalyst slurry to an olefin polymerization reactor in a controlled time sequence. The apparatus includes a feed line for continuously feeding an inert hydrocarbon liquid such as hexane or isobutane to the reactor. A bypass loop is provided in the feed line and is equipped with auxiliary apparatus to charge the loop with a predetermined quantity of catalyst slurry. At preselected timed intervals, the hydrocarbon feed is fed through the bypass loop to sweep the charge of catalyst slurry to the polymerization reactor.