Abstract: An improved process for preparing core/shell MBS modifiers is disclosed, wherein by adding feeds of the monomers which form the second and/or third stage polymers prior to completion of polymerization of the earlier stages, a process with substantially reduced polymerization time results with no loss in properties of the product. The process further includes agglomeration of the rubbery polymer to increase particle size during the polymerization process.

Abstract: In the polymerization of olefins with a vapor phase fluidized bed reactor, the improvement comprises the steps of feeding seed polymer particles and the reaction is then started after feeding an organoaluminum compound on a prescribed basis, thereby avoiding the formation of sheet-like polymer in the initial period of the reaction and the lowering of the bulk density of the product polymer.

Abstract: A melt calendered sheet and a process for making melt calendered sheet having excellent transparency and solvent craze resistance. Clear melt calendered sheet having a critical stress rating above 12,000 KPa, heat distortion temperature above 85.degree. C., and flexural modulus above 3,275 MPa is produced from acrylic copolymer having a melt flow rate of from about 0.3 to about 1.3 grams/10 minutes.

Abstract: An improved process for preparing core/shell MBS modifiers is disclosed, wherein by adding feeds of the monomers which form the second and/or third stage polymers prior to completion of polymerization of the earlier stages, a process with substantially reduced polymerization time results with no loss in properties of the product. The process further includes agglomeration of the rubbery polymer to increase particle size during the polymerization process.

Abstract: A process for producing polypropylene is provided which comprises polymerizing propylene in multiple stages, in the presence of a catalyst which is prepared by reacting a first organoaluminum compound (i), or a reaction product (vi) formed between the first organoaluminum compound (i) and an electron donor (a), with titanium tetrachloride (c) to obtain a first solid product (ii), reacting the resulting first solid product (ii) with the electron donor (a) and an electron acceptor (b) to obtain a second solid product (iii), and combining the resulting second solid product (iii) with a second organoaluminum compound (iv) and an aromatic carboxylic acid ester (v) at a molar ratio of the aromatic carboxylic acid ester to the second solid product (v/iii molar ratio) of from 0.1 to 10.

Abstract: An improved process for making vinyl aromatic/allylic alcohol copolymers is disclosed. Gradual addition of a free-radical initiator during the course of the polymerization results in a substantial increase in the polymer yield obtained compared with the yield from conventional processes in which all of the free-radical initiator is charged initially. The process is particularly useful for making commercially important varieties of styrene-allyl alcohol copolymers.

Abstract: This invention relates to an improved process for the batch polymerization, neat, of a monomer system comprising N-vinyl pyrrolidone monomer utilizing an oil soluble,-thermally activated, free radical initiator. The improvement for reducing the monomer level from about 1 to 2% by weight of the polymerization product to a level below about 0.2 and preferably below about 0.1% by weight of the polymerization reaction product comprises continuously adding an oil soluble azo type free radical generating catalyst to the polymerization reaction product and establishing and maintaining the polymerization reaction product containing residual monomer at a temperature and for a time sufficient to effect substantial polymerization of the residual monomer. Typically the oil soluble, azo type free radical generating catalyst is azobis(isobutyronitrile).

Abstract: This invention relates to a short residence time polymerization reactor operating in periodic mode with multiple catalyst feeds and staged monomer feeds operating to minimize off specification product and optimize and control molecular weight and molecular weight distribution of the polymer produced. This invention contemplates the polymerization of olefins particularly alpha-olefins, particularly ethylene and propylene into homo, co and terpolymers.

Abstract: Elastomeric copolymer obtained by the polymerization of:a) a monomer selected from those having general formula CH.sub.2 .dbd.CR'--CO--OR, wherein R is a monofunctional radical selected from linear or branched C.sub.1 -C.sub.6 alkyl radicals;b) (meth)acrylonitrile;c) a third monomer selected from:c1) a chlorinated vinyl ester;c2) a mixture of an unsaturated carboxylic acid and an aliphatic or aromatic diepoxy compound;c3) a mixture consisting of a chlorinated vinyl ester and an unsaturated carboxylic acid.

Abstract: An in situ process for the preparation of resin particles comprising: preparing a seed particle latex by aqueous emulsion polymerization of a first mixture comprised of at least one monomer, an optional chain transfer agent, and a water soluble free radical initiator, wherein the reaction of the free radical initiator and monomer produces oligomeric radicals which provide in situ stabilization to the resulting first generation seed particles; optionally diluting the first seed particle latex with water; heating and starve feed adding to the first generation seed particles a second mixture comprised of at least one monomer, an organic soluble free radical initiator, an optional chain transfer agent, an optional water soluble free radical initiator, and an optional surfactant to form a third mixture comprised of second generation seed particles; heating and starve feed adding to the second generation seed particles additional said second mixture to form a fourth mixture comprised of third generation seed partic

Abstract: According to the present invention, in a vapor phase polymerization of olefins, there is provided an efficient polyolefin manufacturing process capable of preventing the formation of a sheet-like polymer and allowing an olefin polymerization reaction to be started stably.

Abstract: A method for reducing sheeting during polymerization of an alpha-olefin by feeding either a positive charge generating (MgO, ZnO, Al.sub.2 O.sub.3, CuO, and mixtures thereof) or a negative charge generating (V.sub.2 O.sub.5, SiO.sub.2, TiO.sub.2, Fe.sub.2 O.sub.3, and mixtures thereof) inorganic chemical additive to the reactor responsive to particular static levels in the reactor. The chemical additive is added in amounts which substantially neutralizes the electrostatic charge in the reactor.

Abstract: A process for the polymerization of ethylene and/or one or more alpha-olefins comprising contacting ethylene, and/or the alpha-olefin(s) with a catalyst comprising a first component which is a bis(cyclopentadienyl) Group IVA metal compound containing a substituent capable of reacting with a cation, and a second component which is a compound having a bulky anion containing one or more boron atoms and which is substantially non-coordinating under the reaction conditions and a cation, in which process additional first component is added.

Abstract: A method is provided for controlling the dosage of a fluidized polymerizing catalyst into a polymerization reactor. The method comprises mixing a solid polymerization catalyst with wax and feeding the flowing catalyst-wax mixture through a pipe to the dosage pump. The inlet opening of the cylinder of the dosage pump is opened to draw catalyst-wax mixture through the inlet opening by means of the back motion of the piston. The inlet opening is then closed and the outlet opening is opened. Flowing catalyst-wax mixture is then pressed from the cylinder through the outlet opening by means of the back motion of the piston. The outlet opening is then closed. Opening and closing of the inlet and outlet openings is carried out by rotating an intermediate pipe arranged between the cylinder and piston so that a transmission opening in the intermediate pipe moves upon either the inlet or outlet opening. The intermediate pipe surface always covers at least one of the inlet or outlet openings.

Abstract: The present invention provides a process for preparing a flame retardant styrenic resin which comprises:(1) an initiation step wherein 3 to 10 parts by weight of a bromostyrene compound, 10 to 25 parts by weight of styrene, 5 to 10 parts by weight of an unsaturated nitrile, 0.01 to 0.5 part by weight of a chain transfer agent and 0.01 to 1.0 part by weight of an initiator are introduced to a polymerization reactor and polymerized until the conversion reaches 30 to 50%;(2) a control step wherein 10 to 35 parts by weight of a bromostyrene compound, 20 to 50 parts by weight of styrene, 5 to 20 parts by weight of an unsaturated nitrile, 0.01 to 1.0 part by weight of an initiator and 0.01 to 0.5 part by weight of a chain transfer agent are introduced to the reactor in one or more divisions in accordance with the progress of said polymerization until the conversion reaches 80 to 90%; and(3) an optimization step wherein 3 to 10 parts by weight of styrene, 5 parts by weight or less of an unsaturated nitrile, 0.

Abstract: The invention relates to copolymers containing hydroxyl groups having a hydroxyl value of 50 to 200 mg of KOH/g and an average molecular weight (number average) of 1500 to 6000, which can be prepared by free-radical solution polymerization at temperatures of 130.degree. to 200.degree. C. of 5 to 25% by weight of vinyl ester monomers, 10 to 50% by weight of vinylaromatic monomers, 10 to 50% by weight of hydroxyalkyl ester monomers and, if desired, other monomers, in which the vinyl ester is initially used and the remaining monomers are added over a monomer addition period which is the same for all monomers as follows:i) The amount of the acrylate monomer added per unit time remains constant.

Abstract: (Co)polymer particulates soluble in their corresponding (co)monomer composition, e.g., particulates of acrylic, methacrylic or styrene polymers, are produced by finely dispersing an aqueous phase including at least one polymerization initiator in an organic phase which comprises such (co)monomer composition and at least one nonsolvent for such (co)polymer which is miscible with such (co)monomer composition, and suspended emulsion polymerizing such mixed-phase polymerization recipe.

Abstract: A method for preparing resinous copolymers by sequential charge copolymerization of at least two charges, at least one being a conjugated diene and at least one being a monovinylarene; followed by a charge of a polyfunctional coupling agent; and the final charge being an essentially difunctional coupling agent. The copolymer made by this method and articles made from this copolymer are also provided.

Abstract: There is described a process for the production of an ethanol solution of an ethyl or butyl half-ester copolymer of maleic anhydride and a methyl vinyl ether which comprises: (a) copolymerizing the monomers in acetone as solvent by simultaneously feeding molten maleic anhydride, a molar excess of methyl vinyl ether, and a solution of a free radical initiator in acetone, into a reactor precharged with acetone, at about 68.degree.-85.degree. C., preferably 70.degree.-80.degree. C.; (b) esterifying the acetone solution of said copolymer with ethanol or butanol; and then (c) solvent exchanging ethanol for acetone by continuously injecting vapors of ethanol at about 85.degree.-95.degree. C. into said copolymer solution while simultaneously distilling out acetone therefrom at atmospheric pressure.

Abstract: A process for emulsion polymerization to form a latex having a particle size greater than about 0.5 micrometers by charging to a reaction vessel under agitation a reaction mixture including water, emulsifiers at an initial concentration slightly greater than or equal to the critical micelle concentration, a protective colloid, ethylenically unsaturated monomers, and an ionically balanced combination of an anionic and a cationic water soluble free radical initiator or a nonionic initiator; reacting the mixture to form an emulsion of polymerized monomer; and adding additional monomer, emulsifier, and protective colloid and a water soluble chain transfer agent to the reactor while continuing to agitate the mixture under conditions such that the emulsifier concentration does not exceed that at which new polymeric nuclei are formed.

Abstract: Novel adhesive products are prepared by coating a novel adhesive formulation onto appropriate substrates. The adhesive formulation is capable of maintaining coatable viscosity at solids levels in excess of 58% and may comprise an interpolymer prepared in the presence of a high concentration of chain transfer agents, and may also comprise external and/or internal crosslinking agents. The Williams Plasticity Number of solids from the formulation may be less than 1.8 (determined in the absence of external crosslinking agents). Alkyl acrylamidoglycolate alkyl ether monomer copolymerized with a more reactive monomer provides an interpolymer having reduced need for strong acid catalysis.

Abstract: Free radical polymerization of monomers in the presence of t-amylperoxy pivalate as the free radical initiator is described. Copolymers of maleic anhydride and a vinyl monomer, e.g. a C.sub.1 -C.sub.5 alkyl vinyl ether, and water soluble polyvinylpyrrolidone, are representative polymers prepared in accordance with the process of the invention.

Abstract: A process for preparing copolymer beads suitable for conversion to ion exchange resins, comprising forming a polymeric matrix containing a plurality of free radicals, and continuously adding to said matrix, under conditions suitable for polymerizing a monomer feed which is imbibed by and polymerized within the matrices. Ion exchange resins prepared from beads made by such process exhibit improved osmotic and mechanical properties.

Abstract: An improved wet strength binder is prepared by a process in which interaction between an olefinic carboxylic acid monomer, such as itaconic acid, and a cross-linker, such as MAGME, is minimized.

Abstract: A process for producing a styrene-based polymer having a high syndiotactic configuration, which comprises polymerizing a styrene-based monomer with addition of catalyst in such amounts that the conversion at 30 minutes after the polymerization starts becomes 2 to 50%, and then continuing the polymerization with additions of the catalyst when the conversion exceeds 10%.According to the process, the productivity can be improved while easily attaining safe running of the reactor and successful controlling of reaction heat.

Abstract: The present invention relates to a process and apparatus for the gas-phase polymerization of olefins in a fluidized-bed reactor maintained at a temperature T1. A gaseous reaction mixture comprising the olefins to be polymerized passes through the reactor and is recycled to the reactor by means of a recycling line comprising successively a first heat transfer means, a compressor and a second heat transfer means. The present invention consists in introducing a readily volatile liquid hydrocarbon into the inlet of the first heat transfer means or into the recycling line, upstream and in the vicinity of the first heat transfer means. The first heat transfer means cools the gaseous reaction mixture to a temperature T2, below T1, while volatilizing the readily volatile hydrocarbon and without condensing a constituent of the gaseous reaction mixture. The second heat transfer means cools the gaseous reaction mixture to a temperature T3, below T2, for maintaining the fluidized-bed at the desired temperature T1.

Abstract: A conjugated diene copolymer comprising (A) 40 to 90 mole % of a conjugated diene component, (B) 0.5 to 10 mole % of an alpha,beta-ethylenically unsaturated carboxylic acid component, (C) 0.1 to 5 mole % of a polyfunctional alkenyl compound component and (D) 5 to 58 mole % of a monoolefinically unsaturated compound component wherein the intrinsic viscosity [.eta.] of the copolymer as measured at 30.degree. C. in dimethylformamide is 0.01 to 3.0 dl/g, the width (.DELTA.Tg) of the endothermic transition temperature section determined by a differential scanning calorimetry is 45.degree. to 120.degree. C., and the limit temperature (T.sub.1) on the lower temperature side of the endothermic transition temperature section is -40.degree. C. or less.

Abstract: What is described herein is a solution feed, slurry precipitation polymerization process for making copolymers of maleic anhydride and an alkyl vinyl ether within a predetermined viscosity range.The process of the invention is characterized by precharging a large excess of the alkyl vinyl ether in a reactor, feeding maleic anhydride dissolved in a minimum amount of an organic solvent into the precharged reactor, and polymerizing the monomers in the presence of a free radical initiator. The copolymer product then appears as a pumpable slurry in the reaction medium. The slurry is discharged from the reactor and the desired copolymer is obtained therefrom as a fine, white powder having specific viscosities in the range of about 1.5-6.0, and preferably about 2.6-3.5.

Abstract: There are disclosed copolymers of aromatic vinyl compounds, e.g., styrene, and conjugated diolefins, e.g., butadiene, possessing a differential content of the aromatic vinyl compound such that in at least one of the end portions of the copolymer the differential content shows a sharp and substantial increase in the direction of the outer extremity of the end portion. Preferred compolymers are styrene-butadiene copolymers having a vinyl content of at least 30%. In special embodiments, the copolymer have a styrene content changing in a portion of no more than 5% of the copolymer chain from a first value to a second value, the second value being at least 25 percentage points greater than the first value, and the portion is present within a 10% terminal portion of the copolymer. The copolymers are useful in the tread portions of tires as tires containing such copolymers in the tread composition have improved rolling resistance and/or grip on wet road surfaces.

Abstract: A copolymer of vinylidene fluoride and trifluoroethylene having piezoelectric properties useful at elevated temperatures. The total molar content of trifluoroethylene is less than 30% characterized in that it has a heterogeneous structure with a distribution of accumulated molar composition comprised between two straight lines:Y=-3.18 X +140 andY=-3.12 X +109X is the molar percentage of trifluoroethylene in the macromolecular chains and Y is the percentage by weight of the total of macromolecular chains in which the content of trifluoroethylene is above or equal to X.

Abstract: A polymerization process is provided for producing a terminally functional polymer which comprises introducing a monomer charge, a Lewis acid and an organic peroxy compound into a suitable reaction vessel and polymerizing the monomer charge at a temperature of from about 0.degree. to about -80.degree. C. to form the terminally functional polymer, wherein the monomer charge comprises isobutylene and the organic peroxy compound is charged in an amount of from about 10.sup.-4 to about 10.sup.-1 moles per mole of the isobutylene. In a preferred embodiment, the monomer charge additionally comprises vinylidene aromatic or diolefin monomers. In another preferred embodiment the monomer charge comprises the sequential addition of isobutylene and vinylidene aromatic or diolefin monomers. In a further preferred embodiment said reaction vessel is additionally charged with an electron door having an electron door number of from about 22 to about 50 the amount of said electron door being from about 10.sup.-4 to about 10.

Abstract: ABA triblock polymers that have glycidyl methacrylate as the A segments and (meth)acrylate monomers as the B segment are made by group transfer polymerization, using a monofunctional initiator to make the A, then AB segments. A coupling agent is used to connect the AB segments at the B group.

Abstract: A solution feed, solution polymerization method for making copolymers of maleic anhydride and an alkyl vinyl ether is described. In this process, maleic anhydride in a functional organic solvent is fed into a reactor precharged with an alkyl vinyl ether. The reactant solution is polymerized in the presence of a free radical initiator to provide copolymers in solution having low viscosities and high solids content.

Abstract: A process for producing a heat resistant resin composition, which comprises polymerizing by suspension polymerization a monomer mixture comprising from 30 to 80% by weight of an aromatic vinyl monomer, from 10 to 50% by weight of an N-substituted maleimide monomer, from 10 to 40% by weight of a vinyl cyanide monomer and from 0 to 30% by weight of other vinyl monomer copolymerizable therewith, characterized in that the polymerization reaction is initiated in the presence of a part of the monomer mixture and a part of a suspending agent in the suspension polymerization system prior to the initiation of the polymerization reaction, and then during the polymerization, the rest of the monomer mixture and the rest of the suspending agent are added to the polymerization system continuously or intermittently to complete the polymerization reaction.

Abstract: The present invention includes:(i) a method for making a coated particulate comprising the steps ofheating until liquid a polyolefin wax;fluidizing with a hot gas, additive particles selected from the group comprising an antioxidant, a processing stabilizer, an acid acceptor, and mixtures thereof;spraying the liquid polyolefin wax on the heated fluidized additive particles, andmaintaining the fluidized additive particles at a temperature which is sufficient to prevent the formation of fibers and adequate to form discrete substantially coated additive particles;(ii) a coated particulate made by the above process; and(iii) a process for providing in-reactor stabilization of a polyolefin during a polymerization reaction, using the coated additives prepared by the above described method.

Abstract: A composition having the formula ##STR1## wherein n has an average value of one to about five, is disclosed for use in reducing or eliminating the formation of reactor scale during the polymerization of vinyl chloride and comonomers. The composition is prepared by reacting phenothiazine with formaldehyde in the presence of a liquid diluent that is a solvent for the phenothiazine, but a non-solvent for the dimer of phenothiazine and formaldehyde. The process of the invention is preferably conducted in the presence of a strong acid catalyst. The formaldehyde is preferably added slowly to the reaction mixture over the course of the reaction. The product can be filtered and dried.

Abstract: A process for the continuous preparation of finely divided homopolymers and copolymers of ethene by catalytic polymerization in a circular tube reactor using a liquid alkane as reaction medium in which the ethene or ethene/comonomer mixture to be polymerized is present in dissolved form and the polymer formed is present in suspended form and running the reaction mixture as a cycle stream to which the feed materials are added by bleeding in and from which the polymer formed is withdrawn by bleeding out reaction mixture, comprising (a) maintaining the mean concentration C.sub.m of polymer in the cycle stream at a value within a certain range and (b) effecting the bleeding out of reaction mixture at a point of the cycle stream at which the concentration of polymer has a value which is lower than the mean concentration C.sub.m by a distinct and definite amount.

Abstract: Copolymers of ethylene with vinyl esters are prepared in a continuously operated tubular polymerization system at high pressure and temperatures by feeding a mixture of ethylene, vinyl ester, initiator and, if appropriate, regulant into the polymerization system in the form of a mainstream at the inlet point thereof and at the same time through two or more secondary streams downstream of the inlet point, secondary streams (I) being metered in at points where the reaction temperature has just exceeded a maximum temperature due to the heat of polymerization and secondary streams (II) at points which, relative to the direction of flow of the ethylene, are upstream of the feed points of secondary streams (I) and upstream of the respective maximum temperature.

Abstract: Copolymers of ethylene with acrylates or solutions of free acrylic acid in acrylates are prepared in a continuously operated tubular polymerization system at high pressures and temperatures by feeding a mixture of ethylene, acrylate, initiator and, if appropriate, regulant into the polymerization system in the form of a main stream at the inlet point thereof and at the same time through two or more secondary streams, secondary streams (I) being metered in at points where the reaction temperature has just exceeded a maximum temperature due to the heat of polymerization and secondary streams (II) at points which, relative to the direction of flow of the ethylene, are upstream of the feed points of secondary streams (I) and upstream of the respective maximum temperature.

Abstract: A process is provided for the free radical polymerization of monomers derived from substituted or unsubstituted acrylic acid/methacrylic acid and esters thereof for the production of a polymer having a narrow molecular weight distribution and an average molecular weight of less than 4000. These polymers are produced by the solution polymerizing of said monomers wherein 20-40% by weight of the monomer composition is hydroxyalkyl acrylate or methacrylate in the presence of a solvent system suitable for high solids coating applications and in the presence of an initiating amount of a tertiary alkyl hydroperoxide and/or its derivatives having at least 5 carbons wherein the initiator and monomers, alone or in combination, are added continuously at a programmed rate wherein the rate of addition corresponds approximately to the rate of decomposition of said monomer and initiator. These polymers are used for high solids coating applications.

Abstract: Device and process for introducing a powder with catalytic activity into a fluidized bed polymerization reactor (1), the said device comprising:a storage enclosure (2) for powder with catalytic activity, provided with a feed line (3) for powder with catalytic activity and a shut-off valve (26), this enclosure being connected to a metering device (4) making it possible to deliver periodically a given volume of powder with catalytic activity,an intermediate chamber (5), placed below the metering device to receive direct the powder delivered by the latter, this intermediate chamber comprising in its upper part a tube (6) bringing in an inert carrier gas, provided with a shut-off valve,piping for conveying the powder (8) connecting the bottom part of the intermediate chamber to the fluidized-bed reactor, this piping having a portion which is more or less horizontal, the said powder conveying piping being provided with a full-bore rapid-opening valve (10).

Abstract: A bromate/bisulfite redox initiator system has been found useful for polymerizing tetrafluoroethylene to make resins of good stretch capability.

Abstract: The present invention relates to the production of 1,4-cis-polybutadiene and of copolymers of butadiene with other conjugated diolefins, by means of the catalytic polymerization or copolymerization of monomer butadiene, by an either continuous or batch process, operating in the presence or in the absence of diluents, and carrying out a portionwise addition, during the polymerization, of a portion of the organometallic compound of aluminum (or of the related hydride derivative), constituiting also one of catalytic components.

Abstract: A heat-resistant copolymer obtained by copolymerizing (A) 72-82 parts by weight of .alpha.-methylstyrene and (B) 26-18 parts by weight of acrylonitrile, characterized in that the copolymer contains (a) 0-15% by weight of monomer chain --(A)--(A)--(A)--, (b) 50% by weight or more of monomer chain --(A)--(A)--(B)--, and (c) 50% by weight or less of monomer chain--(B)--(A)--(B)--, the total of (a), (b) and (c) being 100% by weight. This copolymer is excellent in heat stability and moldability when molded at high temperatures, and the blending of this copolymer with other thermoplastic resins gives thermoplastic resins with excellent heat resistance.

Abstract: Copolymers of ethylene containing not more than 4 moles, based on 100 moles of ethylene, of copolymerized C.sub.3 -C.sub.6 -alkenecarboxylic acids are prepared in a continuously operated tubular polymerization system under high pressures and temperatures in the presence of a polymerization initiator by a process in which a mixture of ethylene, the alkenecarboxylic acid, if required a further monomer which is copolymerizable with ethylene, an initiator and, if required, a regulator is fed into the polymerization system at its entrance and at the same time at a second point downstream of the entrance, along the polymerization system, where the reaction temperature has exceeded a maximum, the amount of alkenecarboxylic acid at the entrance of the polymerization system being not more than 0.3, preferably less than 0.28, mole, based on 100 moles of ethylene, and the remainder being metered in at the second feed point.

Abstract: An .alpha.-methylstyrene high-content copolymer which is characterized by that it is a copolymer which comprises 65-90 parts by weight of .alpha.-methylstyrene with 35-10 parts by weight of acrylonitrile and 0-5 parts by weight of a copolymerizable vinyl monomer or monomers and that a component having an .alpha.-methylstyrene content of 82% or higher is contained in an amount of 30 parts by weight or more. Such a copolymer may be produced by a process which comprises charging 65 parts by weight or more of .alpha.-methylstyrene and 10% by weight or less based on this .alpha.-methylstyrene of acrylonitrile and a vinyl monomer or monomers all in one portion at the initial stage, making the system fully emulsified, gradually adding 35 parts by weight or less of acrylonitrile and the vinyl monomer or monomers, and carrying out emulsion polymerization until the amount of a polymer produced has amounted to 50 parts by weight or more in such way that the ratio of the .alpha.

Abstract: A modacrylic fiber comprising a copolymer containing acrylonitrile, at least one of vinyl chloride and vinylidene chloride, and a sulfo group-containing vinyl monomer having a relative reactivity of at least 1 to acrylonitrile, in a specific ratio. The copolymer is prepared by polymerizing the monomers, while adding the sulfo group-containing vinyl monomer to the polymerization system under the following condition:16<Y-X<83wherein X and Y are percentages of the amount of a polymer produced at the time of starting the addition and the amount of a polymer produced at the time of finishing the addition, respectively, based on the amount of the whole polymer to be produced. The fiber has an excellent flame resistance and an excellent devitrification preventing property.

Abstract: A method of converting a continuous olefin polymerization reaction catalyzed by a Ziegler-type catalyst into one catalyzed by a chromium-based catalyst, without the need of emptying and recharging the polymerization reactor, by adding a hydroxyl-containing compound to the reactor containing the Ziegler-type catalyst to interact with such catalyst before the chromium-based catalyst is introduced into the reactor.

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: An oxygen permeable contact lens fabricated from a copolymer of a multifunctional siloxanyl alkylester a monomer selected from the group consisting of, an ester of acrylic or methacrylic acid and from an ester of itaconic acid or mixture thereof. The copolymer can be made either hard, soft, or elasticmeric with improved oxygen permeability.