Abstract: A process for grafting an anhydride of an unsaturated aliphatic diacid onto a polyolefin comprising:(a) passing molten polyolefin through at least two injection zones connected in series;(b) injecting, under grafting conditions, a portion of a solution comprising the anhydride, an organic peroxide catalyst, and an inert organic solvent into the molten polyolefin as it passes through each injection zone, and mixing same in each injection zone until the portion is at least partially grafted onto the polyolefin; and(c) passing the grafted polyolefin, in the molten state, into a devolatilization zone, and mixing same in said zone, under devolatilization conditions, until the grafted polyolefin is essentially devolatilized.

Abstract: It has been determined that certain rubbery polymers having multiple glass transition temperatures can be utilized in making tires which have improved rolling resistance, improved wet skid resistance, and outstanding tread wear. These rubbery polymers are derived from at least one conjugated diolefin monomer, have a first glass transition temperature which is between -110.degree. C. and -20.degree. C. and have a second glass transition temperature which is between -50.degree. C. and 0.degree. C. These rubber polymers can be homopolymers of conjugated diolefin monomers, copolymers of more than one conjugated diolefin monomer, or copolymers derived from at least one conjugated diolefin monomer and at least one vinyl aromatic monomer.

Abstract: A thermoplastic molding material contains, in each case based on the molding material comprising A+B,A from 80 to 60% by weight of a hard matrix composed of polystyrene andB from 20 to 40% by weight of a soft phase which is obtainable by polymerization of styrene in the presence of a linear styrene/butadienne block copolymer which has an ill defined transition, contains from 35 to 45% by weight of styrene and from 65 to 55% by weight of butadiene and has a block polystyrene content of from 25 to 35% by weight, the soft phase being uniformly distributed in the hard matrix and having a particle diameter of less than 0.8 .mu.m.The typical features of the said molding material are that the median particle diameter d.sub.50 (volume average of the soft phase B is from 0.25 to 0.38 .mu.m, the width of the particle size distribution, (d.sub.95 14 d.sub.5), is from 0.2 to 0.6 .mu.m, the d.sub.60 value is from 0.26 to 0.40 .mu.m and the d.sub.90 value is from 0.40 to 0.75.

Abstract: A process for the incorporation of a copolymer of at least one liquid alpha-olefin or diolefin comonomer having at least 7 carbon atoms into a polymer matrix comprising:(a) in a first reaction zone, contacting at least one alpha-olefin having 2 to 6 carbon atoms with a catalyst adapted for the polymerization thereof in such a manner that a granular polymer matrix selected from the group consisting of (i) a homopolymer of ethylene or propylene and (ii) a copolymer of ethylene or propylene and at least one alpha-olefin having 2 to 6 carbon atoms is formed in admixture with active catalyst;(b) admixing the mixture from step (a) with at least one liquid alpha-olefin or diolefin comonomer having at least 7 carbon atoms to at least partially cost the polymer matrix; and(c) introducing the mixture from step (b) into the first reaction zone or a second reaction zone together with at least one alpha-olefin having 2 to 6 carbon atoms in such a manner that polymerization is effected in the gas phase.

Abstract: A branched alpha-olefinic polymer composition having excellent melt flowability, good moldability and excellent melt tension and comprising at least two branched alpha-olefinic polymers each composed of (A) recurring units derived from a branched alpha-olefin containing 5 to 10 carbon atoms and having a branch at the 3-position or a position of a higher number and (B) recurring units derived from a linear alpha-olefin containing 2 to 20 carbon atoms; and a process for producing this polymer composition by a multiplicity of polymerization steps using a catalyst formed from (A) a highly stereoregular titanium catalyst component comprising magnesium, titanium, halogen and an electron donor as essential ingredient, (B) an organoaluminum compound and (C) an electron donor.

Abstract: Process for the preparation of thermoplastic copolymers of .alpha.-methylstyrene and acrylonitrile by continuous bulk copolymerization ofA. 30 to 50 mol % of .alpha.-methylstyrene andB. 70 to 50 mol % of acrylonitrileat temperatures from 60.degree. to 120.degree. C. with average residence times of 4 to 12 hours in the presence of initiators which supply free radicals, carried out in at least two continuously operated mixed tank reactors, characterized in that 100 molar parts of a monomer mixture ofA.sub.0. 34 to 52 mol % of .alpha.-methylstyrene andB.sub.0. 66 to 48 mol % of acrylonitrileare fed continuously into the first tank reactor per unit time, and, with back-mixing, are copolymerized up to a conversion of 5 to 30 molar parts to give a copolymer of the compositionA.sub.1. 49 to 53 mol % of .alpha.-methylstyrene andB.sub.1. 51 to 47 mol % of acrylonitrile,and the mixture consisting of 70 to 95 molar parts of the monomers A and B and 5 to 30 molar parts of the copolymer of the composition A.sub.1 -B.sub.

Abstract: A method for preparing a polymodal MWD ethylene-alpha olefin copolymer using at least two catalysts to initiate growth of polymer chains that attain different average molecular weights. The polymodal MWD ethylene copolymer comprises at least two different molecular weight modes each mode having a narrow MWD and at least one of two characteristics (1) an Mw/Mn of less than 2 and (2) Mz/Mw of less than 1.8.

Abstract: Polymodal MWD ethylene copolymer comprising at least two modes of differing molecular weights. Each mode has at least one of M.sub.w /M.sub.n of less than 2.0, and a M.sub.z /M.sub.w of less than 1.8. The polymodal character of the copolymer is achieved by either (1) withdrawing polymer modes from the reactor from at least one takeoff port, and blending such modes with the reactor effluent, or (2) utilizing at least two catalyst species in the reaction to produce modes of differing molecular weights.

Abstract: Impact-resistant thermoplastic molding materials based on a resin A containing one or more vinylaromatic monomers are prepared by reacting the resin A (component A) with one or more monomers from the group consisting of the .alpha.,.beta.-unsaturated dicarbonyl compounds (component B) by a process in which the reaction is carried out in a melt of A in the presence of B and in the absence of initiators, and the resin A used is one which contains from 3 to 50% by weight, based on A, of one or more elastomers a.sub.1 (rubber) and has been prepared in a conventional manner by polymerizing one or more vinylaromatic monomers of 8 to 12 carbon atoms in the presence of the elastomer a.sub.1 are used for the production of moldings.

Abstract: The invention relates to a continuous flow process for producing polystyrene having discrete particles of rubber included therein. The process utilizes a pre-inversion reactor, in which a solution of styrene, polystyrene and rubber are mixed prior to being introduced into a second stirred tank reactor. The viscosity of the solutions in the pre-inversion reactor and in the second stirred tank reactor are closely controlled to produce desirable HIPS products.

Abstract: A block copolymer of propylene is produced by using propylene itself as a liquid medium, conducting continuous polymerization (former-stage polymerization) of propylene alone or propylene and a small amount of ethylene at first and then conducting batchwise copolymerization (latter-stage polymerization) of ethylene and propylene. The amount of an activity improver to be added to a polymerization tank for the latter-stage polymerization and/or the polymerization time of the latter-stage polymerization are controlled in accordance with the amount of a slurry transferred from a polymerization tank for the former-stage polymerization to the polymerization tank for the latter-stage polymerization so as to maintain the ratio of the amount of the polymer polymerized by the former-stage polymerization to the amount of the polymer polymerized by the latter-stage polymerization constant in the block copolymer.

Abstract: A process for continuously producing a propylene-ethylene block copolymer having well-balanced qualities such as high-impact properties, stiffness, processability, etc., with a good productivity, through two polymerization stages using a stereoregular catalyst comprising a Ti-containing solid catalyst and an organoaluminum compound, is provided, which process is characterized in that at the first stage, propylene is mainly fed into two or more polymerization vessels connected in series, to produce 60 to 95% by weight of the total polymerization quantity, and at the second stage, a specified quantity of a glycol ether is added to the polymerization reaction mixture obtained above and ethylene is fed in a relatively large quantity into one or more polymerization vessels, to produce 5 to 40% by weight of the total polymerization quantity.

Abstract: A process for pretreating a Ziegler-type catalyst for use in olefin polymerization reactions. An olefin monomer is aded to a fluid carrier stream containing a Ziegler-type catalyst. The carrier stream containing the monomer and the catalyst is passed through an elongated tubular reactor at a flow rate sufficient to provide a residence time in the tubular reactor of less than 1 minute and under temperature conditions to prepolymerize the catalyst within the tubular reactor without plugging of the reactor. In a specific embodiment the residence time within the reactor is no more than 10 seconds, and more particularly, no more than 2 seconds.

Abstract: Maleic anhydride can be satisfactorily grafted to polymers at low pressures by feeding the polymer through a co-rotating, twin-screw extruder and injecting the maleic anhydride and a free radical initiator into the extruder. The maleic anhydride and initiator can be pre-mixed in a solvent solution. The solvent and unreacted maleic anhydride can be removed by low pressure devolatilization.

Abstract: A continuous polymerization process for producing a high-melt viscoelastic ethylene-propylene copolymer by the use of Ziegler-Natta catalyst, which process make it possible to stably produce an ethylene-propylene block copolymer having superior physical properties suitable to sheet molding and blow molding and capable of producing large-size molded products is provided,which process comprises(a) feeding propylene and ethylene in a weight proportion of ethylene in the total of propylene and ethylene of 0-5% into 3 or more polymerization vessels among 4 or more polymerization vessels connected in series, to carry out continuous polymerization step (i) and successively feeding ethylene and propylene in a weight proportion of ethylene in the total of ethylene and propylene of 10-100% into one or more polymerization vessels, to carry out continuous polymerization process (ii); (b) feeding the total quantity of the catalyst only to the first polymerization vessel; (c) feeding the total quantity of hydrogen substant

Abstract: A propylene-ethylene block copolymer is produced by continuous bulk polymerization in which propylene alone is polymerized or propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio of 6/94 using propylene as a liquid medium, and subsequently by batch-wise copolymerization in which propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio from 85/15 to 5/95.

Abstract: The present invention relates to a multistage, continuous process for the preparation of propylene-ethylene impact copolymers comprising the use of a plug flow pipeline reactor for homopolymerizing propylene, a gas-phase fluidized bed reactor for additional propylene homopolymerization, and a gas-phase fluidized bed reactor for propylene/ethylene copolymerization.

Abstract: The present invention relates to a multistage, continuous process for the preparation of propylene-ethylene impact copolymers comprising the use of a recirculating pipe-loop reactor for homopolymerizing propylene, a cyclone separator for removing fines, a gas-phase fluidized bed reactor for additional propylene homopolymerization, and a gas-phase fluidized bed reactor for propylene/ethylene copolymerization.

Abstract: Disclosed is a method for producing a vinyl aromatic resin composition containing a rubber in a disposed state which comprises from 60 to 90% by weight of a copolymer of a vinyl aromatic monomer with an unsaturated dicarboxylic anhydride in which the content of the vinyl aromatic monomer as a monomer unit is from 70 to 98 mol % and the content of the unsaturated dicarboxylic anhydride as a monomer unit is from 2 to 30 mol %, from 10 to 35% by weight of a graft copolymer and from 0 to 9% by weight of a diene based rubber, by copolymerizing the vinyl aromatic monomer with the unsaturated dicarboxylic anhydride in the presence of the diene based rubber, wherein said method comprises.

Abstract: Copolymers which contain, as copolymerized monomer units, monoethylenically unsaturated mono- and dicarboxylic acids are prepared by a process in which(a) from 10 to 60% by weight of a monoethylenically unsaturated dicarboxylic acid of 4 to 6 carbon atoms, its salt and/or, if appropriate, its anhydride,(b) from 90 to 40% by weight of a monothylenically unsaturated monocarboxylic acid of 3 to 10 carbon atoms and/or its salt and(c) from 0 to 20% by weight of another, carboxyl-free monoethylenically unsaturated monomer which is copolymerizable with (a) and (b),the percentages being based on the sum of the monomers, are polymerized in the presence of from 0.5 to 5% by weight of a water-soluble free-radical-forming initiator in an aqueous medium at from 60.degree. to 150.degree. C.

Abstract: A process for the gas phase production of a sticky, but fluidizable, polymer comprising (i) introducing at least one gaseous monomer, which is a precursor for the polymer, into a bed of particles located in a fluidized bed reactor at a velocity sufficient to cause the particles to separate and act as a fluid; (ii) introducing into the bed a catalyst adapted to cause the monomer to polymerize; (iii) contacting the catalyst with the monomer at a temperature below the sticking temperature of the polymer and at a temperature and pressure sufficient to polymerize the monomer in the presence of the catalyst whereby the polymer is produced; and (iv) passing the polymer from the fluidized bed reactor into at least one fluid bed reactor wherein a fluidizing gas is passed through a bed of particles at a velocity sufficient to cause the particles to separate and act as a fluid; the polymer is passed through the fluid bed reactor in an essentially plug flow mode; and the polymer is maintained in an agitated state.

Abstract: A process and apparatus as shown in FIG. 1 for the production of polyolefins by the polymerization of alpha-olefins in the gas phase, in several stages, in at least two polymerization reactors interconnected by a transfer device making it possible to transfer the polyolefins resulting from the first reactor into the second reactor, in which the polymerization is continued under conditions identical to or different from those of the first reactor.

Abstract: Rubber-modified thermoplastic resins are characterized by having a high content of olefinically unsaturated nitriles and good transparency. These thermoplastic resins generally comprise from about 43 to about 75 parts by weight of a monovinyl aromatic monomer, from about 20 to about 40 parts by weight of an olefinically unsaturated nitrile monomer and from about five to about 35 parts by weight of an unsaturated dicarboxylic acid anhydride monomer, providing 100 parts of a thermoplastic terpolymer, and from about two to about 30 parts by weight of rubber polymer per 100 parts of the thermoplastic terpolymer. Other resins characterized by having between about 30 to 45 parts by weight of unsaturated dicarboxylic acid anhydride exhibit good heat distortion temperatures.

Abstract: In a process for producing an olefin polymer which comprises continuously polymerizing an olefin in the presence of a catalyst composed of a transition metal compound component and an organometallic compound component in at least two independent polymerization zones connected in series by a pipeline while feeding the olefin and the catalyst into an upstream zone of polymerization and withdrawing the resulting polymer from a downstream zone of polymerization; the improvement wherein(1) the polymerization in the upstream polymerization zone is carried out in a liquid medium under conditions for slurry polymerization,(2) the solid polymer-containing slurry discharged from the upstream polymerization zone is fed into a liquid medium exchanging zone through an upper feed opening (A) in its upper portion, said liquid medium exchanging zone being provided between the upstream polymerization zone and the downstream polymerization zone and connected to these zones by pipelines, and an additional supply of the liquid m

Abstract: A thermoplastic polymer comprising a styrenic monomer, an acrylate, a methacrylate and a block copolymer is provided which possesses an unexpected excellent balance of properties including good physical properties, good elongation and a high degree of transparency. Also provided are processes for the preparation of the thermoplastic polymer.

Abstract: A rubber-reinforced copolymer comprising a copolymer matrix derived from one or more monovinylidene aromatic compounds and one or more unsaturated nitrile compounds having at least 6 percent of a rubber which exhibits a viscosity, as a 5 weight percent solution in styrene, of at least 120 centipoise dispersed as discrete particles throughout the copolymer matrix at a particle size of less than 1.5 micron.

Abstract: In a continuous bulk or solution polymerization process for producing rubber modified high-impact resins which comprises continuously feeding a raw material solution comprising a mixture of an aromatic vinyl monomer and a vinyl cyanide monomer and a rubber component dissolved in the mixture, together with a radical polymerization initiator, to a first reactor, polymerizing the raw material solution under high-shear agitation to a conversion required to transform the rubber component phase into dispersed particles, withdrawing the reaction mixture continuously from the first reactor at a rate corresponding to the feed rate of the raw material solution, and feeding the reaction mixture to a second or more reactors for further polymerization, rubber modified high-impact resins exhibiting excellent chemical resistance, thermal resistance and rigidity and having a good surface gloss can be produced by properly determining the weight ratio of the aromatic vinyl monomer to the vinyl cyanide monomer present in the ra

Abstract: A process for the continuous preparation of rubber-modified polymers of vinyl-aromatics, wherein a mixture which contains a monomeric aromatic vinyl compound and from 3 to 30% by weight, based on the monomer, of an elastomeric polymer, with or without a solvent, is polymerized, in the presence of a free radical initiator and in the presence or absence of a mercaptan as chain transfer agent, at from 80.degree. to 180.degree. C., with stirring, in a cascade of two or more isothermally operated reaction zones and of one or more additional reaction zones which can be operated isothermally or with a rising temperature profile in such a way that the residence time of the reactants in the first reaction zone is .ltoreq.35 minutes. The polymer obtained is freed from vinyl-aromatic monomer, and from any solvent, in a devolatilization zone. The product is useful for the production of injection moldings.

Abstract: A method is provided for producing thermoplastic polymer blends with the exposure of blend constituents to extreme blending conditions minimized by melting the thermoplastic polymers and adjusting their viscosity and elasticity values, through control of their melt temperatures, prior to blending. Where the viscosity and elasticity values are adjusted properly, the desired thermoplastic polymer blend can be produced with a minimum effort.

Abstract: A process for the preparation of ethylene-propylene impact copolymers at improved catalyst productivity rates involving the formation of a propylene prepolymer by polymerization of propylene in liquid phase in the presence of a catalyst system containing titanium halide supported on magnesium halide and aluminum alkyl complexed with an electron donor. Ethylene and propylene are block polymerized onto the prepolymer in a vapor phase reaction zone in the presence of a second catalyst system comprising a solution of a C.sub.5 -C.sub.9 polyalpha-monoolefin/catalyst/diluent.

Abstract: A process for the preparation of rubber-modified thermoplastic compositions having high temperature stability includes the steps of dissolving a rubber polymer in a solvent selected from the group consisting of monovinyl aromatic monomers, olefinically unsaturated nitriles and mixtures thereof to form a feed solution, introducing the feed solution into a reactor capable of intimately mixing multiple immiscible phases, introducing into the reactor a separate liquid monomer feed stream containing monomers selected from the group consisting of unsaturated dicarboxylic acid anhydrides, olefinically unsaturated nitriles and mixtures thereof, heating the feed solution and feed stream under pressure to a temperature sufficient for polymerization to begin and intimately mixing and polymerizing the monomers around the rubber polymer in the reactor to form a thermoplastic resin composition.

Abstract: The disclosure is directed to improvements in a process for preparing curable polyolefin polymers in which a mass of dry, discrete, free-flowing particles of polyolefin polymer is tumbled in admixture with a curing agent effective to cause curing when the finished product is subjected to curing temperature, which comprises tumbling said mass in two separate and discrete steps in which essentially all of the curing agent is incorporated into said mass in the first tumbling step and equilibration between the curing agent and the polymer is effected in the second tumbling step while maintaining in both tumbling steps a temperature above the melting point of said curing agent but below both the agglomerating temperature and the curing temperature and, at least in the second tumbling step, a temperature which provides equilibration between the curing agent and the polymer; and thereafter tumble-cooling the thus-treated mass until a dry, discrete, free-flowing mass of polymer particles is obtained.

Abstract: A process for the preparation of ethylene-propylene impact copolymers at improved catalyst productivity rates involving the formation of a propylene prepolymer by polymerization of propylene in liquid phase in the presence of a catalyst system containing titanium halide supported on magnesium halide and aluminum alkyl complexed with an electron donor. Ethylene and propylene are block polymerized onto the prepolymer in a vapor phase reaction zone in the presence of further added quantities of aluminum alkyl components.

Abstract: Continuous halogenation of polymers is achieved by contacting polymer and halogenating agent in a continuous flow device in which the reactants are present as either co-continuous phases or wherein the halogenating agent is present as a continuous phase and the polymer is present as a discontinuous phase, the polymer is subjected to deformation during reaction and in which means are provided for disengaging reaction by-products and unreacted halogenating agent from the reaction mixture. In a preferred embodiment the polymer passes through three extruder-reactor zones under controlled conditions to achieve halogenation: feed, reaction (preferably vented), neutralization, and optionally a wash and exit zone. A continuous halogenating agent phase is achieved during reaction by avoiding complete filling of the reaction zone with polymer. Various halogenated polymers are produced, for example, halogenated linear low density polyethylene and halogenated butyl rubber.

Abstract: The present invention relates to a process for producing a polypropylene-ethylene block copolymer by a continuous multi-stage polymerization comprising a first stage in which polypropylene is polymerized in a first polymerization vessel in the presence of a propylene polymerization catalyst, and a second stage in which propylene and ethylene are copolymerized in a second polymerization vessel, wherein the polypropylene slurry discharged from the first polymerization vessel is supplied to a concentrator to separate said slurry into a concentrated polypropylene slurry and a supernatant liquid, the concentrated polypropylene slurry is then introduced through an upper part of a hydraulic sedimentation classifier to be contacted with a countercurrent of the upward flowing of the supernatant fluid introduced through a lower part of said classifier to obtain hydraulically sedimented polypropylene, and non-hydraulically sedimented polypropylene; the thus obtained hydraulically-sedimented polypropylene is then supplie

Abstract: A continuous process for producing star-block copolymer of a monovinyl aromatic monomer and a conjugated diene by continuously forming a vinyl aromatic polymer having a low weight average molecular weight to number average molecular weight ratio in a first reactor by anionic initiation in a solution of inert solvent; discharging a solution of polymer from the first reactor and passing the solution to a second sealed, cylindrical, pressurized, vertical reactor having a bottom zone, top zone and a plurality of intermediate zones separated by separation plates, each having a central aperture and mixing shaft passing therethrough, with the mixture passing to successive zones through an annular space formed between the shaft and each separation plate.

Abstract: Mass graft copolymerization carried out in an extrusion passageway having a sealing zone to prevent back flow of grafting material introduced to the extrusion passageway downstream of the sealing zone.

Abstract: An olefin copolymer rubber graft composition having a viscoelastic performance index of not greater than 100 as defined by the expressionPI=(DS.times.MV)/i.v.where DS is the die swell of the composition, MV is the melt viscosity of the composition and i.v. is the intrinsic viscosity of a resinous portion extracted from the composition.

Abstract: Apparatus and method of preparing a partially hydrolyzed polymer solution, especially a partially hydrolyzed polyacrylamide solution, for use in secondary and tertiary oil recovery operations which involves the in-line introduction of a relatively concentrated solution of a hydrolyzing agent into a polymer stream having a relatively high concentration of the polymer, and thereafter intimately mixing, under heat, the polymer stream and the hydrolyzing agent while controlling the flow rate of the reaction mixture. The reaction mixture is then held in a post hydrolysis tank where the reaction is allowed to go to completion.

Abstract: A process for the impact modification of a plastic with a rubber polymer to form a thermoplastic resin in a reactor extruder is provided. The process includes the steps of dissolving a rubber polymer in a solvent selected from the group consisting of ethylenically unsaturated monomers and non-polymerizable organic compounds to form a feed solution, introducing the feed solution into the feed section of a twin screw reactor extruder, introducing a separate feed stream containing a material in sufficient amount to precipitate the rubber polymer, heating the feed solution and feed stream under pressure to a temperature sufficient for polymerization to begin, polymerizing the monomers with the rubber polymer in the reactor extruder to form a thermoplastic resin and extruding the thermoplastic resin through a die. A novel ABS thermoplastic resin is also provided having a uniform distribution of rubber particles dispersed within the plastic phase of the resin, the rubber particles ranging in size of from about 0.

Abstract: Polyethylene is produced in at least one reactor under a pressure of 800 to 2500 bars and a temperature of 150.degree. to 350.degree. C., and the reaction mixture exiting the reactor through an expansion valve and supplied to a separator under a pressure of 50 to 400 bars is cooled by passing a flow Q of the mixture through a turbine. The turbine comprises at least one stage with a fixed nozzle and a bladed wheel having a rotation speed of between 12,000 and 40,000 r.p.m. Ethylene discharged from the separator is recycled to the inlet of a compressor, and the discharge from the compressor is supplied to the reactor.

Abstract: Propylene/ethylene block copolymers are prepared by a process in which, in an agitated bed comprising small polymer particles, first (I) propylene is homopolymerized from the gas phase, in a first polymerization zone, by feeding in a Ziegler-Natta catalyst comprising (1) a titanium(III) component and (2) a dialkyl-aluminum chloride component, with or without (3) a further catalyst component, and then (II) the product obtained in the first polymerization zone is fed into a second polymerization zone, where a mixture of propylene and ethylene is polymerized with the propylene homopolymer present in this product.In this process, the Ziegler-Natta catalyst employed contains a titanium(III) component (1) which is prepared by subjecting (1.1) a titanium-containing compound (a) of the formula TiCl.sub.3. nAlCl.sub.3 and (1.2) an electron donor (b), consisting of (b.sub.1) an ester of a particular class or (b.sub.

Abstract: Propylene/ethylene block copolymers are prepared by a process in which, in an agitated fixed bed comprising small polymer particles and in each case in the presence of hydrogen, first (I) propylene is homopolymerized from the gas phase, in a first polymerization zone, by feeding in a Ziegler-Natta catalyst, and then (II) the product obtained in the first polymerization zone is fed into a second polymerization zone, where a mixture of propylene and ethylene is polymerized with the propylene homopolymer present in the product from the first polymerization zone.

Abstract: The present invention relates to a method for the production of high impact polystyrene utilizing a continuous process in place of the previously known batch polymerization techniques. The continuous process includes the steps of rubber solution preparation; prepolymerization; second stage polymerization; devolatilization and separation extrusion and pelletizing.

Abstract: An ethylene-.alpha.-olefin copolymer composition comprising two ethylene-.alpha.-olefin copolymers which are different in density, intrinsic viscosity and the number of short chain branching per 1000 carbon atoms. Extrusion processed materials, injection molded materials and films obtained from said composition are excellent in strength.

Abstract: Molding materials containing high molecular weight polyphenylene ethers are produced by a process in which a solution of a polyphenylene ether in an organic solvent, together with another polymer, is freed of solvent by multi-stage evaporation.The solvent is preferably an aromatic compound from the class comprising the hydrocarbons, halohydrocarbons, ethers or esters, the ratio of the other polymer to the polyphenylene ether is advantageously from 99:1 to 20:80 parts by weight, the other polymer is, in particular, a homopolymer or copolymer of styrene or of a homolog thereof, which may be modified with rubber, and the multi-stage evaporation process preferably comprises not less than two and not more than four working up stages.The evaporation is carried out in general at from 120.degree. to 280.degree. C. and under a pressure of from 1 to 3,000 mbar, advantageously in the presence of assistants which reduce the partial pressure, eg. water and/or methanol.

Abstract: Live polyethylene slurry is treated with small amounts of ethylene in the absence of hydrogen, for example in the drier. By using this procedure it is possible to prepare polymers with very high, controllable levels of swell. In contrast to previous procedures reported for dual stage polymerizations, the melt flow ratios are not appreciably altered.

Abstract: Impact-resistant modified styrene polymers having the characteristics: molecular weight M.sub.v 150,000 to 170,000; gel content exceeding 22%; degree of swelling of 11.5 to 13.5 and a mean gel particle diameter of 1.7 to 4.5 microns are produced by continuously polymerizing a styrene solution of polybutadiene, possibly in the presence of diluents, by means of a cascade consisting of at least three continuous stirred tank reactors, at rising temperatures and in the presence of organic peroxide initiators. The process steps are carried out as follows:(a) in a first continuous stirred tank reactor, a continuously introduced solution of styrene containing from 8 to 10.

Abstract: A propylene block copolymer produced by polymerizing propylene, ethylene and an .alpha.-olefin having 4 to 8 carbon atoms in two stages with a Zieglar-Natta catalyst by a process which comprises (A) supplying propylene and ethylene in the first stage and propylene and the .alpha.-olefin in the second stage, or (B) supplying propylene and the .alpha.-olefin in the first stage and propylene and ethylene in the second stage, to the polymerization system, wherein the amounts of propylene and ethylene supplied in the first stage of (A) or in the second stage of (B) are 90 to 99 wt % and 10 to 1 wt % based on the total amount of propylene and ethylene supplied in the first stage of (A) or in the second stage of (B), respectively, the amounts of propylene and the .alpha.-olefin supplied in the second stage of (A) or in the first stage of (B) are 60 to 98 wt % and 40 to 2 wt % based on the total amount of propylene and the .alpha.

Abstract: Mass graft copolymerization carried out in an extrusion passageway having a sealing zone to prevent back flow of grafting material introduced to the extrusion passageway downstream of the sealing zone.