Abstract: A solid catalyst component for .alpha.-olefin polymerization containing as catalyst components at least titanium, magnesium and chlorine which are impregnated into an organic porous polymer carrier having a mean particle diameter of 5 to 1,000 .mu.m and a pore volume of 0.1 ml/g or above at a pore radius of 100 to 5,000 .ANG., a catalyst system comprising at least said solid catalyst component (A) and an organoaluminum compound (B), as well as a process for producing .alpha.-olefin polymers using said catalyst system.

Abstract: A process for the in situ blending of polymers comprising continuously contacting, under polymerization conditions, a mixture of ethylene and at least one alpha-olefin having at least 3 carbon atoms present in an amount of about 0.1 to 3.5 mole per mole of ethylene with a catalyst in at least two fluidized bed reactors connected in series, said catalyst comprising:(i) a complex consisting essentially of magnesium titanium, a halogen, and an electron donor;(ii) at least one activator compound for the complex having the formula A1R".sub.e X'.sub.f H.sub.g wherein X' is C1 or OR"'; R" and R"' are saturated aliphatic hydrocarbon radicals having 1 to 14 carbon atoms and are alike or different; f is 0 to 1.5; g is 0 or 1; and e+f+g=3; and(iii) a hydrocarbyl aluminum cocatalyst, the polymerization conditions being such that ethylene copolymer having a high melt index in the range of about 0.

Abstract: The present invention relates to .alpha.-olefin block copolymers excellent in adhesive property to polar group-containing polymers and metals as well as in rigidity comprising an alkenylsilane and an .alpha.-olefin and processes for preparing the same, materials for adhesion and for easy coating comprising the same.

Abstract: Vinyl ether copolymers and a method of preparing the same. The vinyl ether is copolymerized with styrene, alkyl-substituted styrenes, alkoxy-substituted styrenes and mixtures thereof. In the process, a cadmium halide is used with hydrogen iodide or a suitable iodine containing electrophile, as the coinitiator.

Abstract: Propylene/ethylene polymers are prepared by a process in which, in each case in the presence of hydrogen and by means of gas phase polymerization, first (A), in a first polymerization zone, propylene is homopolymerized, and the resulting propylene homopolymer is introduced into (B) a second polymerization zone, where a mixture of propylene and ethylene is then polymerized with the reaction product obtained in (A). In this process, ethylene is homopolymerized in a further polymerization zone (C), likewise by gas phase polymerization, with certain provisos, and the resulting reaction product is likewise fed to the second polymerization zone (B).

Abstract: Propylene/ethylene block copolymers are prepared by a continuous process in which, in each case in an agitated fixed bed of finely divided polymer from the gas phase, first (I) in a first polymerization zone, propylene is homopolymerized by feeding in a Ziegler-Natta catalyst system consisting of (1) a titanium component which contains titanium, magnesium, chlorine and a phthalic acid derivative, (2) an aluminumalkyl component and (3) a silane component, and (II) in a second polymerization zone, a mixture of propylene and ethylene is polymerized with the propylene homopolymer present in the reaction mixture obtained in the first polymerization zone by feeding in the said reaction mixture. In the process, (A) a titanium component (1) is used which is obtained by a method in which (1.1) first, (1.1.1) in a liquid hydrocarbon, (1.1.2) a finely divided magnesium halide, (1.1.3) an alkanol, (1.1.4) a certain phthalic acid derivative and (1.1.

Abstract: Process for production of a molded article comprising polymerizing a norbornene monomer having bicyclic or higher cyclic structure in the presence of a metathesis catalyst system and a viscosity modifier having room temperature viscosity of 300 to 50,000 cps which viscosity modifier comprises a ring-opened polymer and unreacted norbornene monomer having bicyclic or higher cyclic structure.

Abstract: The disclosure relates to a graft polymerization method to form a fluorine-containing graft copolymer which is useful as a soft and flexible fluororesin intermediate between fluororubbers and crystalline fluororesins. The graft copolymer is formed by polymerizing a fluorine-containing crystalline polymer, e.g. copolymer of CTFE and ethylene, in water in the presence of a reducing agent and a fluorine-containing elastomeric copolymer which comprises peroxy groups and is dispersed in the water to become the "trunk" of the graft copolymer. For example, the elastomeric copolymer is of vinylidene fluoride, CTFE and t-butyl peroxyallylcarbonate. An example of the reducing agent is sodium bisulfite, and optionally and additionally a source of a reducing metal ion such as ferric chloride may be used. This graft polymerization reaction can be carried out at a relatively low temperature, viz. at 20.degree.-50.degree. C.

Abstract: The present invention relates to a process for the polymerisation of ethylene or copolymerisation of ethylene and at least one other alpha-olefin, in the gas phase in a fluidised bed reactor, in the presence of a catalyst comprising chromium compounds associated with a granular support comprising a refractory oxide and activated by thermal treatment, which process is characterised in that the catalyst is used in the form of active particles of prepolymer, obtained by bringing the said catalyst in contact with ethylene, alone, or in a mixture with at least one higher alpha-olefin, in such a way that the prepolymer contains from 4.times.10.sup.-5 to 3 milligram atoms of chromium in the catalyst per gram.

Abstract: A novel low-crystalline propylene random copolymer composition comprising[I] 60 to 95% by weight of a propylene random copolymer and[II] 5 to 40% by weight of a low-crystalline propylene random copolymerwhich has excellent heat-sealability, heat-seal imparting property, transparency and antiblocking property and containing a reduced amount of a hydrocarbon-soluble component, a process for production thereof, and polypropylene composite laminated structure having improved heat-sealability and heat seal strength at low temperatures.

Abstract: During the reaction of grafting of styrene and acrylonitrile to polybutadiene, the conversion of the graft monomers is increased from the values of 92.div.94% usually obtained, to values very close to 98%, by carrying out a redox-type reaction additional to that provided by the process, in the presence of an additional aliquot of acrylonitrile and of catalytic system.

Abstract: A process for the production of .alpha.-olefin block copolymer particles having excellent impact resistance at low temperature and excellent molding and processing characteristics, is disclosed. The process includes a two step gas phase polymerization procedure under specific conditions in the presence of a specific catalyst system.

Abstract: Disclosed is a method of making a cross-linked poly(dicyclopentadiene) with a metathesis-catalyst system, where the metathesis-catalyst system contains an organoaluminum or organoaluminum halide activator and a pentavalent tantalum catalyst. In a preferred embodiment, the cross-linked polymer is formed by combining, in a first place, a plurality of reactant streams, one reactant stream which contains the activator, a second reactant stream which contains the catalyst and at least one reactant stream which contains dicyclopentadiene; then injecting the combined reactant streams into a second place, such as a mold, where polymerization occurs. Use of the pentavalent tantalum catalyst results in the formation of a cross-linked polymer having less color and greater transparency than cross-linked poly(dicyclopentadiene) made without a pentavalent tantalum catalyst.

Abstract: A method for producing an .alpha.-olefin block copolymer, which comprises polymerizing propylene alone or together with a small amount of other .alpha.-olefin in the presence of a catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound, and then polymerizing the resulting propylene polymer with an .alpha.-olefin other than propylene, alone or together with propylene in a gas phase without deactivating the catalyst, characterized in that the gas phase polymerization is conducted in the presence of a siloxane or a polysiloxane in an amount of from 1.times.10.sup.-6 to 0.1 by weight ratio relative to the weight of said propylene polymer.

Abstract: Large acrylic star polymers containing multifunctional monomers in the core are made by group transfer polymerization techniques, preferably by arm-first, core-first, or arm-core-arm approaches.

Abstract: The invention relates to a process for the controlled polymerization of alpha-olefins selected from the group consisting of propylene and butylene in order to form a polymer containing by weight about 10% to 30% isotactic polyolefin, 25% to 70% atactic polyolefin and 0% to 65% by weight of an amorphous ethylene/olefin copolymer which process comprises combinations of the steps of:(a) homopolymerizing the alpha-olefin at a temperature of from about 0.degree. C. to about 90.degree. C. (preferably from about 20.degree. C. to about 60.degree. C.) in the presence of a high yield catalyst comprising a titanium compound supported on activated MgCl.sub.

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 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 process for producing a propylene block copolymer in the presence of a highly stereospecific olefin polymerization catalyst which comprises producing a crystalline polymer or copolymer of propylene in a first stage and random-copolymerizing propylene and another alpha-olefin in a mole ratio of from 10:90 to 90:10 in the presence of the propylene polymer or copolymer in a second stage; wherein in the random copolymerization, 0.0001 to 0.5 mole, per gram atom of aluminum in the catalyst, of an oxygen-containing compound being gaseous in a standard condition or 0.001 to 1 mole, per gram atom of aluminum in the catalyst, of an active hydrogen-containing compound being liquid or solid in a standard condition is fed into the random-copolymerization reaction system.

Abstract: Disclosed are polypropylene compositions having high impact resistance at low temperatures, and improved whitening resistance. They comprise:(a) 60-90 parts by weight of polypropylene with an isotacticity index >90; and(b) 10-40 parts by weight of an ethylene/butene-1 polymeric mixture containing 50-95% by weight of polymerized ethylene, and consisting essentially of:20-95% by weight of a crystalline fraction (I) with crystallinity of the polyethylene type, that is insoluble in xylene at 23.degree. C.; and5-80% by weight of an ethylene/butene-1 amorphous copolymeric fraction (II), that is soluble in xylene at 23.degree. C., and contains 40-70% by weight of ethylene;and in which the weight ratio between total polymerized ethylene and the amorphous fraction (II) is 0.6-8.

Abstract: A diene polymer composition having improved fracture properties and a small change in the shape of extruded product is disclosed, which comprises at least 5% by weight of a copolymer composed of at least one conjugated diene (component A) having the following general formula: ##STR1## wherein R.sub.1 and R.sub.2 are a hydrogen atom or a methyl group, and 2,3-dimethylbutadiene (component B), said copolymer having a content of cis-1,4-bond of not less than 80%.

Abstract: A process for preparing a catalyst component for the polymerization of olefins which comprises the steps of contacting (a) a magnesium dialkoxide soluble in an inert solvent, (b) a silicon compound having the hydrogen-silicon bond, and (c) an electron donor compound with one another in the presence of an inert solvent, and contacting the resulting reaction product with (d) a titanium compound.

Abstract: Electrically conductive polymer blends of an acetylene polymer and an elastomer having a low level of unsaturation are disclosed herein. The low level of unsaturation provides resistance to heat, light, oxygen and ozone and yet provides sufficient sites for crosslinking of the blend to provide increased stability. These blends exhibit high conductivity upon doping with electron donors or electron acceptors.

Abstract: Disclosed is a method of making a cross-linked poly(dicyclopentadiene) with a metathesis-catalyst system, where the metathesis-catalyst system contains an organoaluminum or organoaluminum halide activator and a pentavalent tantalum catalyst. In a preferred embodiment, the cross-linked polymer is formed by combining, in a first place, a plurality of reactant streams, one reactant stream which contains the activator, a second reactant stream which contains the catalyst and at least one reactant stream which contains dicyclopentadiene; then injecting the combined reactant streams into a second place, such as a mold, where polymerization occurs. Use of the pentavalent tantalum catalyst results in the formation of a cross-linked polymer having less color and greater transparency than cross-linked poly(dicyclopentadiene) made without a pentavalent tantalum catalyst.

Abstract: A process for producing a propylene copolymer having improved transparency and rigidity, which comprises carrying out (A) the polymerization of a vinyl cycloalkane having at least 6 carbon atoms and (B) the polymerization of propylene either alone or with ethylene in a multiplicity of steps in the presence of a catalyst system composed of a titanium compound and an organoaluminum compound. The content of the vinyl cycloalkane unit in the resulting copolymer is 0.05 to 10,000 weight ppm.

Abstract: The invention relates to a catalyst system comprising (a) a compound of a rare earth element and, as cocatalyst, a second component (b) comprising an organomagnesium compound. In the polymerization of a conjugated diene this catalyst gives a polymer having a very high content of trans 1,4 isomer. A third component (c) which is a Lewis acid alters the reaction to give a polymer having a very high content of cis 1,4 isomer. If desired reaction can be initiated using components (a) and (b) alone and component (c) then added at the desired conversion to produce a block polymer having a block of high trans content followed by a block of high cis content.

Abstract: The production of impact-resistant polystyrene with EPDM simplifies the process and produces improved products if a modified ethylene/propylene rubber consisting of styrene/butadiene- or diene polymers, ethylene, optionally propylene and an unconjugated diene are used as the elastifying component.The modified EPDM rubbers consisting of (a) from 20 to 90% by weight of ethylene units, (b) from 1 to 25% by weight of units of a butadiene/styrene copolymer containing a quantity of from 10 to 90% by weight of styrene, (c) from 0 to 10% by weight of units of an unconjugated diolefin and (d) C.sub.3 -C.sub.18 .alpha.-monolefin units to make up the difference to 100% by weight, are a further subject of this invention.

Abstract: A 3-methylbutene-1 polymer composition comprising from 10 to 95% by weight of a 3-methylbutene-1 homopolymer, or a copolymer of 3-methylbutene-1 with other .alpha.-olefin having from 2 to 12 carbon atoms, which has a 3-methylbutene-1 content of higher than 90% by weight, and from 5 to 90% by weight of a copolymer of 3-methylbutene-1 with other .alpha.-olefin having from 2 to 12 carbon atoms, which has a 3-methylbutene-1 content of from 40 to 90% by weight, and a process for its production.

Abstract: EPDM rubbers having improved properties are obtained by carrying out the polymerization using a catalyst system consisting of a vanadium compound, an aluminum halide and an ester, the ester being a polymer containing ester groups.

Abstract: A process for modifying the surface characteristics of a pre-formed polymeric substrate to impart hydrophilicity, hydrophobicity, or other desired properties thereto, by peroxidizing the surface of the substrate and then allowing the active sites along the polymer chains to generate free radicals which induce graft polymerization of a suitable ethylenic monomer (or other ethylenically-unsaturated compound) onto the surface of the substrate is described. Such graft copolymerization is undertaken in the presence of variable valence metal ions in a reduced state under acidic conditions and at selected reaction times and relatively low temperatures, and ideally in the presence of squarate ions (diketocyclobutenediol) to control the physical characteristics of the surface graft and to restore the metal ions to their lower valence state without at the same time producing deleterious by-products.

Abstract: A diene polymer produced by polymerizing a conjugated diene monomer in a solvent solution of an active lithium-terminated polymer in the presence of a catalyst consisting of (A) a cobalt compound and (B) carbon disulfide and/or phenylisothiocyanic acid. The diene polymer comprises a 1,2-polybutadiene portion having a high percentage of vinyl conformation. The diene polymer has substantially no mercaptan compound.

Abstract: A polypropylene molding composition with a good hardness and good impact strength at low temperatures is formed by two-stage polymerization of propylene and ethylene in liquid propylene in the presence of a special supported catalyst.

Abstract: A process for producing a propylene block copolymer by a three-step reaction in the presence of a stereoregular catalyst. At the first step, propylene is polymerized at a temperature of 55.degree. C. or more to form polypropylene having an intrinsic viscosity of from 0.5 to 3.5 in the prescribed amount. At the second step, propylene is polymerized at a temperature of from 30.degree. to 90.degree. C. to form polypropylene having an intrinsic viscosity of at least 4 in the prescribed amount. And at the third step, ethylene and propylene are copolymerized at a temperature of from 30.degree. to 90.degree. C. to form an ethylene-propylene copolymer having an intrinsic viscosity of at least three in the prescribed amount. The propylene block copolymer formed by the three steps is superior and well balanced in impact resistance and stiffness.

Abstract: A propylene-ethylene block copolymer from which molded products having high rigidity and superior high-impact properties can be prepared even without adding any particular additive, is provided, which copolymer is obtained by (i) polymerizing propylene in 70 to 95 weight % based on the total polymerized amount, using a catalyst obtained by reacting an organoaluminum compound (I) or a reaction product of (I) with an electron donor (A), with TiCl.sub.4, further reacting the resulting solid product (II) with (A) and an electron acceptor (B), and combining the resulting solid product (III) with an organoaluminum compound (IV) and an aromatic carboxylic acid ester (V), the molar ratio of (V) to (III) being 0.1 to 10.0, and then (ii) polymerizing ethylene or ethylene and propylene in 30 to 5 weight % based on the total polymerized amount, at one or more stages, using the same catalyst as above, the ethylene content being 3 to 20 weight % based on the total polymerized amount.

Abstract: A process for producing a chemically blended propylene polymer composition having an ethylene content ranging from 3 to 40% by weight and being greater than the weight of the rubbery propylene copolymer formed in stage (II) below, which comprises the following stages (I) and (II):(I) a first stage of polymerizing propylene containing 0 to 5 mole % of another olefin in the presence of a catalyst composed of (A) a solid titanium catalyst component consisting essentially of titanium, magnesium, halogen, and an electron donor, (B) an organoaluminum compound, and (C) an organic silicon compound having an Si--O--C bond or an Si--N--C bond to thereby form a crystalline propylene polymer or copolymer; and(II) a second stage of polymerizing propylene and ethylene, or propylene, ethylene and another olefin in the presence of the reaction product of the first stage and the same catalyst as used in the first stage to form a rubbery propylene copolymer and a crystalline ethylene polymer or copolymer.

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 whitening-resistant, highly melt-viscoelastic ethylene-propylene copolymer and process for producing the same are provided, which copolymer is produced by copolymerizing ethylene with propylene in the presence of a specified stereoregular catalyst and at four stages under specified conditions, the catalyst being prepared by reacting an organoaluminum compound or its reaction product with an electron donor, with TiCl.sub.4, reacting the resulting solid product with an electron donor and an electron acceptor, and combining the resulting solid product with an organo-aluminum compound and an aromatic carboxylic acid ester so as to give a specified ratio, and at the four stages, the ethylene contents in monomers fed, the proportion of polymerization amounts and the intrinsic viscosities of polymers formed being specified.

Abstract: Graft polymers such as grafted polyacetylene and devices based on derivatives of these polymers are produced utilizing a specific process. The process includes the steps of polymerizing a monomer such as acetylene in the presence of a host polymer such as polyisoprene to produce a graft polymer. The use of a host polymer yields several desirable results. For example, when the graft polymerization is performed in the presence of a solvent for an appropriate host polymer, the entire graft polymer is solvated. The solvated graft polymer is then employable to produce films of polymers on a substrate which are in turn useful in structures such as devices.

Abstract: Polypropylene compositions having high impact strength at low temperatures comprising as essential components:100 parts by weight of polypropylene having an isotacticity index >90,8-25 parts by weight of an amorphous copolymeric fraction (1) of ethylene-propylene soluble in xylene at 23.degree. C., containing 20-80% by weight of ethylene,2-10 parts by weight of an ethylene-propylene crystalline copolymeric fraction (2) having a crystallinity of the polyethylene type containing 50-90% by weight of ethylene;and in which the weight ratio between the total polymerized ethylene and fraction (1) is <1.The compositions are prepared by polymerization processes comprising at least a step of homopolymerization of propylene to stereoregular polymer and a subsequent step of polymerization of ethylene-propylene mixtures in the presence of catalysts comprising a titanium compound carried on a magnesium halide in active form.

Abstract: A method of making a thermoset polydicyclopentadiene by first combining a plurality of reactant streams, one containing the activator of a metathesis-catalyst system, a second containing the catalyst of a metathesis-catalyst system and at least one containing dicylopentadiene; then immediately injecting this combination into a mold where polymerization results in the formation of a tough, rigid thermoset polymer with high modulus and excellent impact strength.

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: An ethylene-propylene block copolymer capable of producing foamed shaped articles having a structure of uniform and fine foams even without adding any other resins, and a process for producing the same are provided, which copolymer consists of a propylene homopolymer portion and an ethylene-propylene (EP) copolymer portion and is characterized in that .circle.1 the former portion is obtained by polymerizing propylene at two stages so that the portion can further consist of a lower molecular weight portion and a higher molecular portion; .circle.2 between the melt flow rates of the resulting block copolymer under a specified load and five times the load, there is a specified relationship; .circle.3 the EP copolymer portion has an ethylene content of 60 to 95% by weight based on this portion; and .circle.4 the block copolymer has an ethylene content of 10 to 40% by weight based on the copolymer.

Abstract: A process for polymerizing 1,3-butadiene, comprising bring into contact a 1,2-polymerization catalyst consisting essentially of a soluble cobalt compound, an organic aluminum halide, an organic lithium compound, and carbon disulfide or phenyl isothiocyanate with 1,3-butadiene in a polymerization medium. The process can be applied particularly advantageously in the preparation of 1,2-polybutadiene, and the resultant 1,2-polybutadiene has a content of syndiotactic 1,2-structural units of not less than 90%, a melting point of 200.degree. C. to 220.degree. C., and an intrinsic viscosity [.eta.] of 1.2 to 7.

Abstract: A 1,2-polymerization of 1,3-butadiene is carried out in a polymerization solvent in the presence of a 1,2-polymerization catalyst consisting essentially of a cobalt compound soluble in the polymerization solvent, an organic aluminum halide, an organic magnesium compound, and carbon disulfide and/or phenyl isothiocyanate and in the presence or absence of a cis-1,4-polymerization product of 1,3-butadiene.

Abstract: A polypropylene (PP) having a superior post-processability and blow moldability is provided, which PP is obtained by polymerizing propylene at multiple stages using a catalyst comprising a TiCl.sub.3 composition, an organoaluminum compound and a molecular weight (M.W.) modifier, the resulting final polymer comprising a higher M.W. portion and a lower M.W. portion having a melt flow index of 0.03 to 2.0 g/10 min., and between this index and a melt flow index (10.2 kg/10 minutes, 230.degree. C.) as measured under 5 times the load applied in the measurement of the former melt flow index, there being a relationship log HMI.gtoreq.0.922 log MI+1.44, and the final polymer consisting of 40 to 60 weight % of a PP portion corresponding to the higher M.W. portion and 60 to 40 weight % of a PP portion corresponding to the lower M.W. portion.

Abstract: Thermoplastic elastomeric sequentially prepared propylene and (ethylene-propylene) polymer, or propylene, (ethylene-propylene) and propylene polymer, made in solvent medium with catalyst system based on (a) complex of titanium tetrachloride and alkyl benzoate or a phenol, supported on magnesium dihalide and (b) trialkyl aluminum modified by electron rich substituted benzoate.

Abstract: Block copolymers are prepared by using two successive and different catalytic processes, a Ziegler-Natta type polymerization followed by a conventional anionic polymerization.

Abstract: A polybutadiene rubber having an enhanced mechanical strength is produced in such a manner that the contents of water and carbon disulfide in a solution of 1,3-butadiene and carbon disulfide in an inert organic solvent is controlled to 0.2 to 5 m moles and 20 m moles or less, respectively, per liter of the 1,3-butadiene-carbon disulfide solution; a first polymerization mixture is prepared from the controlled 1,3-butadiene-carbon disulfide solution, an organic aluminum compound of the formula Al R.sub.n X.sub.3-n, wherein R=C.sub.1-6 alkyl, phenyl, or cycloalkyl, X=halogen, and n=1.5-2.

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: An alpha olefin polymerization reaction using a first alpha olefin monomer and a magnesium supported titanium halide/aluminum alkyl catalyst system wherein said system comprises:(a)(i) a procatalyst component;(ii) a cocatalyst component; and(iii) a selectivity control agent;(b) discontinuing addition of the procatalyst component;(c) adding sufficient sterically hindered phenolic hydrocarbon to the polymerization reaction contents to terminate the reaction; and(d) either(i) adding an amount of a second alpha olefin monomer and then adding an organoaluminum compound to restart the reaction; or(ii) adding an amount of said first alpha olefin monomer and a second alpha olefin monomer and then adding an organoaluminum compound to restart the reaction; or(iii) adding an amount of said first alpha olefin monomer and a second alpha olefin monomer and then adding an amount of an organoaluminum compound and additional procatalyst.