Abstract: Olefins are polymerized with a catalyst which forms on mixing a supported chromium oxide composite and an adjuvant which is 1,3,5-cycloheptatriene or an alkyl-substituted derivative thereof. This system allows the production of polymer of a given melt index at a higher temperature.

Abstract: Ethylene is polymerized, in the presence of hydrogen, at a temperature of 180.degree. to 340.degree. C and a pressure of 200 2,500 bars with a Ziegler catalyst in a stirred reactor having at least one first reaction zone and at least one second reaction zone. The reaction mixture is fed to a separator at a pressure of 80 to 400 bars. The improvement results from partially liquifying at least a part of the gas coming from the separator at a temperature of -50.degree. to +20.degree. C, releasing the pressure to a value of 10 to 60 bars, separating the partially liquified gas into a gas phase and a liquid phase, and recycling the gas phase to the second reaction zone and the liquid phase to the first reaction zone. The resulting polymer has a low melt index, a high polydispersity index, and superior physical properties compared to polymers prepared by conventional processes.

Abstract: Ethylene-vinyl acetate polymer is modified by reaction with a polyfunctional acrylate which improves the processing characteristics of the polymer. The cured modified polymers exhibit improved properties including lower hardness and greater dimensional stability.

Abstract: High nitrile polymers modified with the addition of selected amounts of low molecular weight polyethylene have improved processing properties including increased melt flow and significantly inhibited color formation when processing at high shear and high temperatures.

Abstract: Auxiliary agents for improving the retention of flushable solids and for accelerating the drainage of suspensions, for more rapid treatment of solid and liquid substances which can be utilized industrially, such as industrial water, effluents and sludges, inter alia in the paper industry, and for improving the structure of soils, this auxiliary agents being in the form of suitable high-molecular, water-soluble acrylamide polymers obtained by solution polymerization, and also relates to a process for the preparation of this auxiliary agents.

Abstract: Ethylene-vinyl acetate copolymers or saponified copolymers are carboxylated by copolymerizing an alpha, beta-unsaturated carboxylic acid and/or anhydride thereof with or without at least one vinylidene monomer having the formula: ##STR1## wherein X and Y can be the same or different, and each represents hydrogen, chlorine, alkyl, acetoxy, carboxylic acid ester group or cyano; with an ethylene-vinyl acetate copolymer or a saponified copolymer thereof in the presence of a polymerization initiator in a reaction medium of an acetic acid ester or a mixture of an acetic acid ester and a lower alcohol, wherein the reaction is conducted in a heterogeneous state.

Abstract: A chromium-containing catalyst utilizing spray dried silica gel containing titanium is used to produce olefin polymers exhibiting an outstanding resistance to environmental stress cracking.

Abstract: Catalysts for the polymerization of ethylene and the copolymerization of ethylene with other olefins have been prepared by depositing an organo-chromium compound on a silica support which has been fluorided at low temperatures.

Abstract: A method for the continuous manufacture of hydrocarbon resins starting from polymerizable insaturated hydrocarbons adapted to selectively obtain clear resins having well determined viscosities or softening points and to control the temperature of the polymerization reaction conducted in the presence of a Lewis acid as catalyst and recycling a fraction of the reaction mixture, due to the improvement comprising the steps of forming a close mixture of the catalyst and of the hydrocarbon fraction to be polymerized in a reactor, said mixture containing, by weight, from 0.05 to 0.8 part, and preferably from 0.1 to 0.

Abstract: A two-stage cyclical process for producing alkene polymers of wide molecular weight distribution, in which high molecular weight polyalkenes are produced in one stage and lower molecular weight polyalkenes are produced in the other stage and in which polyalkene from one of said stages is introduced into the other of said stages.

Abstract: A concentrated solution of a water-soluble vinyl monomer is mixed at or below room temperature with an effective amount of a peroxygen catalyst and the resulting solution is freed of inhibitory oxygen and thereafter atomized into a reaction vessel containing an atmosphere of gaseous sulfur dioxide to produce a polymer product by redox catalysis.

Abstract: A process for preparing a polytetrafluoroethylene fine powder by polymerizing tetrafluoroethylene in an aqueous medium containing a polymerization initiator and a dispersant, coagulating the resulting polymer, washing the coagulated polymer when desired, and drying the polymer, characterized in that after at least 30 wt. % of the whole amount of the tetrafluoroethylene to be polymerized has been polymerized at a constant temperature, the polymerization is conducted at an altered temperature at which the same whole amount, when polymerized, gives a polymer having an amorphous index at least 0.01 higher than when the whole amount is polymerized at the first-mentioned temperature.

Abstract: Vinyl chloride monomers or a monomeric mixture composed mainly of vinyl chloride is bulk-polymerized in a polymerization vessel. The inner walls and other surfaces of said vessel, coming into contact with the monomer or monomers, are coated with one or more specifically selected inorganic or organic compounds having a solubility greater than 0.5 g in 100 g of water at 25.degree. C and a boiling point higher than 60.degree. C. This bulk polymerization method serves to greatly reduce the deposition of polymer scale on the vessel walls and other surfaces. In addition the polymer scale deposited can be readily separated and removed by merely washing with water or gas under pressure. The present method provides high quality polymers.

Abstract: Novel composite polymer particles are obtained, under specified conditions, by preparing an aqueous suspension comprising 100 parts by weight of propylene polymer particles, 5 - 200 parts of a vinyl or vinylidene monomer, and a specific polymerization initiator; heating the aqueous suspension to impregnate the propylene polymer particles with the monomer; and then raising the temperature of the aqueous suspension to complete polymerization of the monomer. The resultant composite polymer is improved in molding, mechanical, chemical and physical properties and is useful as molding or forming material as it is or as a blend with another polymeric material.

Abstract: This invention relates to copolymers of a macromolecular compound having a non-halogenated and double-bonded chain and of a vinylaromatic monomer and the process for obtaining same. The reaction between the macromolecular compound and the vinylaromatic monomer takes place at a temperature of between -80.degree. C and +40.degree. C in the presence of 5.10.sup.-4 to 5.10.sup.-2 mol/l of a Lewis acid initiator and possibly in the presence of a co-initiator. These copolymers obtained by cationic grafting are thermoplastics elastomers.

Abstract: A process for the manufacture of olefin polymers by polymerizing .alpha.-monoolefins of 2 to 8 carbon atoms by means of a catalyst which is obtained from a silicon-containing material (component a), an organo-metallic compound containing alkyl groups (component b) and a chromium compound (component c), wherein the catalyst employed is obtained by (1) first bringing into contact (1.1) an alkogel (component a) of the empirical formula SiO.sub.2 .multidot. m Al.sub.2 O.sub.3 .multidot. n ROH, where m is a number from 0 to 2, n is a number such that the content of ROH in the alkogel is from 1 to 85 per cent by weight and R is alkyl of 3 to 8 carbon atoms, and (1.2) an aluminum compound containing certain alkyl groups (component b), with intimate mixing, to form a solid-phase reaction product, (2) then bringing into contact (2.1) the solid-phase reaction product obtained from stage (1) and (2.

Abstract: In the emulsion polymerization of a dienic monomer or a mixture containing a dienic monomer and at least one other copolymerizable monomer in an aqueous medium, the deposition of polymer scale on the inner walls of the polymerization reactor and other surfaces in contact with the monomer or monomeric mixture can be remarkably reduced or prevented by providing coating layers of an organopolysiloxane on those surfaces, prior to the polymerization, by applying the organopolysiloxane directly to the surfaces or by applying one or a mixture of hydrolyzable organosilanes to the surfaces, followed by hydrolysis-condensation of the silanes, to form the organopolysiloxane in situ.

Abstract: .alpha.-Ethylenically unsaturated monomers are polymerized in aqueous media in a vessel with electrically conductive inner surface, in which partial areas of the inner surface covered by liquid are electrically insulated from the remaining surface areas and conductively connected therewith by an external source of current. In this manner the formation of deposits on the wall of vessel is hindered or suppressed.

Abstract: There is disclosed an improved bulk-suspension process for polymerizing vinyl aromatic monomers in the presence of an ethylene-propylene-nonconjugated diene-rubber, which comprises using, in the suspension polymerization step, peroxy-carbonic esters as the polymerization initiator. The process of the invention yields products having improved notched impact strength, weatherability and elongation at break combined with a good shear stability.

Abstract: In a process for polymerizing ethylene in a two-zone autoclave reactor comprising a top reaction zone and a bottom reaction zone which process comprises polymerizing ethylene in said top reaction zone at 130.degree. to 200.degree. C and at a reaction pressure of 1,000 to 1,800 kg/cm.sup.2 using an initiator, sending the resulting reaction mixture from the top reaction zone to the bottom reaction zone, and further promoting the polymerization at 220.degree. to 280.degree. C using an initiator which is same as or different from the initiator in the top reaction zone, the improvement which comprises feeding 75% or more of the ethylene to the top reaction zone of the two-zone reactor, said two-zone reactor being constructed so that the volume ratio of top reaction zone to bottom reaction zone is 1.5 to 6 and being provided with two or more feed inlets for each of the ethylene and the initiator in the top reaction zone in the direction extending through the two reaction zones.