Abstract: The invention relates to a method for producing caoutchouc particles (K) by means of emulsion polymerisation in the presence of an emulsifier and a polymerisation initiator. Said particles contain A) 80 to 100 wt. % of one or more conjugated diene monomers (A) in relation to (K) and B) 0 to 20 wt. % of one or more monoethylenically unsaturated comonomers (B) in relation to (K) in the polymerised form. The inventive method is characterised in that 1) a mixture (M1) containing water and an emulsifier is provided, 2) a mixture (M2) containing one or more monomers in the monomer or polymerised form selected from styrole, &agr;-methylstyrole, butadiene, n-butylacrylate, MMA and acrylnitrile and optionally comonomers is added, 3) polymerisation of the obtained mixture starts in the presence of a polymerisation initiator at temperature of 5 to 95° C., 4) a mixture (M3) containing 0 to 100 wt. % of the comonomers (B) in relation to (B) and 0 to 25 wt.

Abstract: A process for synthesizing syndiotactic 1,2-polybutadiene, the process comprising the steps of (1) polymerizing monomer consisting essentially of 1,3-butadeine monomer within an organic solvent that includes at least 50% by weight of aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutadiene, (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutadiene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene is desired, and (3) isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution.

Abstract: The present invention relates to a rubbery polymer which is comprised of repeat units that are derived from (1) at least one conjugated diolefin monomer, and (2) at least one functionalized monomer of the structural formula: 1

Abstract: This invention is a solution process for the preparation of ethylene-a-olefin-diolefin copolymers comprising contacting ethylene, one or more a-olefin monomer, and one or more cyclic diene monomer, with a catalyst composition comprising a bridged, bis(cyclopentadienyl) zirconium compound having an unsubstituted cyclopentadienyl ligand, a multiply substituted cyclopentadienyl ligand, said ligands bridged by a covalent bridging group containing one or more Group 14 element, and two uninegative, activation reactive ligands and a catalyst activator compound. The invention process exhibits high catalyst activity, high comonomer incorporation and high diene monomer conversion rates and is particularly suitable for the preparation of elastomeric ethylene-propylene or ethylene-propylene-diene monomer elastomers.

Abstract: An ethylene styrene copolymer having isolated styrene monomer units separated by 5 or 6 methylene groups as determined by 13C-NMR may be polymerized in the presence of an activator and a transition metal catalyst containing a phosphinimine ligand.

Abstract: An emulsion polymerization process for the preparation of polybutadiene grafted with styrene and acrylonitrile monomers in a reaction system is provided. The resultant product has a low end content of unreacted residual monomers, low yellowness index, and improved impact strength. The diene rubber is prepared via a process wherein a chain transfer agent is added on a continuous basis to give a rubber substrate having a low crosslink density. In one embodiment of the invention, the process includes charging the reaction system with a pre-selected diene emulsion with a low crosslink density, adding a first portion of at least one of a styrene monomer and acrylonitrile monomer to the diene emulsion, adding to the reaction system, over a predetermined time, an initiator and a second portion of acrylonitrile and styrene monomer, and polymerizing the catalyzed reaction mixture of diene substrate, styrene and acrylonitrile to form ABS graft polymers.

Abstract: The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b1) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a free radical initiator or b2) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, the (co)polymers obtainable by this process and the use of multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in combination with a free radical initiator, or a multi-functional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled polymerization. In a particularly preferred embodiment at least one additional heating step at a temperature from 140 to 280° C. is applied after polymerization is completed.

Abstract: The invention relates to a new catalyst system that improves the heat transfer capability of a butyl reactor slurry process system in the production of random copolymers of one or more isoolefin monomers and one or more conjugated diene monomers in continuous slurry polymerization processes. The process is carried out in an anhydrous polymerization system containing a mixture of the monomers in a polar diluent along with a Lewis acid and a C5 or greater initiator having a tertiary halide.

Abstract: The present invention relates to highly branched and coupled polymers based on conjugated dienes or on conjugated dienes and vinylaromatic compounds and on polyfunctional, organic compounds with at least four groups which are capable of coupling. Vulcanization products and shaped rubber articles of all types, in particular tires having an improved rolling resistance, can be produced from the highly branched diene polymers according to the present invention.

Abstract: An objective of the invention is to provide a conjugated diene-based rubber having a specific composition and an oil extended rubber using the same, as well as a rubber composition capable of being converted into a vulcanized rubber which has a low rolling resistance, an excellent wearing resistance and the like, and is useful for a tire or the like. A conjugated diene-based rubber in the invention has repeating units consisting of 1 to 30% by mass of an olefinically unsaturated nitrile monomer unit such as acrylonitrile, 10 to 50% by mass of an aromatic vinyl monomer unit such as styrene, 19.9 to 88.9% by mass of a conjugated diene monomer unit such as 1,3-butadiene and 0.1 to 10% by mass of a monomer unit having one polymerizable unsaturated group and at least one functional group selected from the group consisting of an amino group, a hydroxyl group, an epoxy group, a carboxyl group and an alkoxysilyl group, and has a specific glass transition point and a Mooney viscosity [ML1+4(100° C.

Abstract: This invention discloses a process for synthesizing an amine functionalized monomer that comprises (1) reacting a secondary amine with a 2,3-dihalopropene to produce a vinyl halide containing secondary amine having a structural formula selected from the group consisting of 1

Abstract: The invention discloses a method for preparing a triblock copolymer of the formula: comprising: (a) contacting a cycloalkene with a chain transfer agent of the formula: Z—Y═Y—Z  in the presence of a metal carbene metathesis catalyst to form a telechelic polymer; and (d) contacting the telechelic polymer with an alkene of the formula  in the presence of an ATRP organometallic catalyst wherein n and m are integers; Z is an ATRP initiator and —Y═Y— is an alkenyl group; and, R′ is selected from the group consisting of aryl, nitrile and C1-C20 carboxylate, wherein R′ is substituted or unsubstituted. The invention also discloses a method for preparing a diblock copolymer. In addition, the invention encompasses a triblock copolymer having no 1,2-PBD structure in the PBD portion of the copolymer.

Abstract: The present invention relates to rubber mixtures containing diene rubber with a concentration of primary hydroxyl groups of 0.1 to 2 wt. % and a glass transition temperature of −120° to −50° C. and their mixtures with fillers, optionally further rubbers and rubber auxiliary substances and vulcanisates prepared therefrom. Rubber mixtures according to the invention are suitable for producing highly reinforced, abrasion-resistant moulded items, in particular for producing tires treads which have a particularly high resistance to wet skidding.

Abstract: Butene oligomer derivatives having tert-butyl groups as one of the terminal groups, having a repeating unit of the main hydrocarbon chain consisting of 80% by mole or more of —CH2C(CH3)2—, and carrying the other terminal group consisting of 60% by mole or more of 1,4-butanediol type functional groups. These derivatives are useful as macromonomers which can be subjected to polycondensation, polyaddition, etc.

Abstract: A process for the preparation of a reaction product (A) comprises the following stage (i):

Abstract: A catalyst system suitable for use in the production of high cis polybutadiene is disclosed. The catalyst system includes a cobalt salt of the formulaCoAx?, where A is a monovalent or divalent anion and x is 1 or 2; an alkyl aluminum chloride compound of the structure R2AlCl, where R is an alkyl group containing 2-8 carbon atoms; a trialkyl aluminum compound of the formula R3Al, where R is an alkyl group containing 2-8 carbon atoms; and a catalytic amount of water.

Abstract: The present invention provides a method for polymerizing conjugated diolefins in the presence of a catalyst of the rare earth metals and in the presence of an aromatic vinyl compound. The diolefins produced thereby may find use in producing rubber-modified molding materials, such as ABS and HIPS.

Abstract: It has been discovered that the polymerization of diene compounds, such as butadiene, may be inhibited by the addition of a composition that contains at least one hindered or unhindered phenol, in combination with low nitrogen content component which is a stable nitroxide and/or a hydroxylamine substituted with at least one alkyl, aryl or alkylaryl group; and/or a second, different hindered or unhindered phenol, and optionally a hydrogen transfer agent.

Abstract: The invention is directed to a pneumatic tire having at least one component comprising a vulcanizable rubber composition, wherein the vulcanizable rubber composition comprises, based on 100 parts by weight of elastomer (phr), from about 30 to 100 phr of high trans random SIBR, and from about zero to about 70 phr of at least one additional elastomer, wherein the high trans random SIBR comprises from about 3 to about 30 percent by weight of styrene.

Abstract: The present invention provides synthetic polyisoprenes having a high cis-1,4 linkage content and a process for their preparation. The synthetic polyisoprenes according to the invention have a cis-1,4 linkage content, measured by carbon-13 nuclear magnetic resonance and/or medium-wave infrared radiation analysis, which lies within a range from 99.0% to 99.6%. The process for the preparation of these synthetic polyisoprenes involve polymerizing, at a temperature of 0° C. or lower, isoprene in the presence of a catalytic system based on: a) a conjugated diene monomer, b) an organic phosphoric acid salt of one or more rare earth, c) an alkylaluminium alkylating agent of the formula AlR3 or HAlR2, and d) a halogen donor consisting of an alkylaluminium halide, wherein the salt is suspended in at least one inert, saturated aliphatic or alicyclic hydrocarbon solvent and the alkylating agent: rare earth salt molar ratio ranges from 1 to 5.

Abstract: Initiators for nitroxide-mediated radical polymerizations are described. The initiators have an azlactone or ring-opened azlactone moiety to provide telechelic (co)polymers.

Abstract: New ligands, compositions, metal-ligand complexes and arrays with bridged bis-aromatic ligands are disclosed that catalyze the polymerization of monomers into polymers. These catalysts with metal centers have high performance characteristics, including higher comonomer incorporation into ethylene/olefin copolymers, where such olefins are for example, 1-octene, propylene or styrene. The catalysts also polymerize propylene into isotactic polypropylene.

Abstract: Disclosed is a binder for a lithium-sulfur battery including a butadiene-based copolymer. The binder exhibits chemical resistance to polysulfides, is stable a battery working temperatures, forms an emulsion in organic solvents and exhibits high adherence to positive active materials and electrodes used in the lithium-sulfur battery. The disclosed binder compositions, due to their high adherence to positive active materials allow for higher relative amounts of positive active materials to be used in the battery resulting in a high capacity lithium-sulfur battery.

Abstract: The present invention provides a catalytic system that can be used to prepare by polymerization diene elastomers comprising polyisoprenes and polybutadienes. The invention also provides a process for the preparation of the catalytic system and to a process using the catalytic system to prepare diene elastomers comprising polyisoprenes having a high cis-1,4 linkage content and polybutadienes. The catalytic system according to the invention is based on (a) a conjugated diene monomer, (b) an organic phosphoric acid salt of a rare earth metal, (c) an alkylating agent consisting of an alkylaluminium of the formula AlR3 or HAlR2, and (d) a halogen donor consisting of an alkylaluminium halide, and is such that said salt is suspended in at least one inert and saturated aliphatic or alicyclic hydrocarbon solvent and, the “alkylating agent:rare earth salt” molar ratio ranges from 1 to 5.

Abstract: Initiators for nitroxide-mediated radical polymerizations are described. The initiators have an azlactone or ring-opened azlactone moiety to provide telechelic (co)polymers.

Abstract: The present invention provides a novel process for the preparation of isoolefin copolymers in the presence of zirconium halides and/or hafnium halides and organic acid halides, in particular for the preparation of butyl rubbers, as well as isoolefin copolymers constructed of isobutene, isoprene and optionally further monomers.

Abstract: Process for the production of statistic elastomeric conjugated diene-vinyl arene copolymers having a branched structure which comprises: (1) anionic copolymerization in solution of the conjugated diene and vinyl arene monomers, in the presence of randomizing agents and an initiator selected from the group of Lithium alkyls, the copolymerization being carried out until the almost total disappearance of the monomers; (2) addition to the solution of step (1) of a quantity of Lithium alkyl from 1 to 4 times the molar quantity of the Lithium alkyl of step (1); (3) addition to the polymeric solution of step (2) of a compound having the general formula R—Br, the molar ratio between R—Br and the total Lithium alkyl ranging from 0.6/1 to 1/1, preferably from 0.7/1 to 0.9/1, thus obtaining an elastomeric branched copolymer.

Abstract: It has been discovered that the polymerization of unsaturated compounds, such as butadiene, may be inhibited by the addition of a diene and/or alkanolamine inhibitor. The inhibitor is believed to catalytically destroy peroxides present, such as hydrogen peroxide, which may be present in trace amounts. Particularly useful inhibitors include, but are not limited to, ethylenediamine (EDA) and monoethanolamine (MEA).

Abstract: This invention discloses a chewing gum rubber composition (gum base) that utilizes carnosic acid from a Libiatae plant, such as rosemary or sage, as an antioxidant stabilizer. This invention more specifically discloses a chewing gum base comprising: (1) about 5 weight percent to about 95 weight percent of a rubbery elastomer; (2) about 0 weight percent to about 75 weight percent of an elastomer plasticizer selected from the group consisting of natural rosin esters and synthetic terpene resins; (3) about 1 weight percent to about 65 weight percent of a filler material; and (4) carnosic acid, wherein said chewing gum base is void of sweeteners, flavoring agents or colors.

Abstract: The process and catalyst system of this invention can be utilized to synthesize polybutadiene rubber having a high trans content and a low melting point by solution polymerization. The trans-polybutadiene rubber made by the process of this invention can be utilized in tire tread rubbers that exhibit outstanding wear characteristics. More importantly, the trans-polybutadiene rubber of this invention can be easily processed because of its low level of crystallinity. In fact, the trans-polybutadiene made by the process of this invention does not need to be heated in a “hot-house” before being used in making rubber compounds.

Abstract: This invention relates generally to synthetic procedures that include the step of ring-opening metathesis of cyclic olefins and reaction with an acyclic diene co-reactant to produce regularly repeating A,B-alternating olefin polymers. The A,B-alternating polymers are produced by varying reaction conditions and/or reactant proportions and using only two types of olefin metathesis (ring-opening and cross) to provide regularly repeating ABAB . . . etc. polymers via ring-opening metathesis polymerization (ROMP). More particularly, the invention pertains to synthesis of A,B-alternating olefin polymers via olefin metathesis reactions using a Group 8 transition metal complex as the metathesis catalyst. Polymers provided herein have utility in a variety of fields, including not only polymer chemistry per se, but also in the pharmaceutical, biomedical, and packaging industries where the structure and properties of polymers need to be tightly controlled.

Abstract: This invention relates generally synthetic procedures that include the step of ring-opening metathesis of cyclic olefins and reaction with an acyclic diene co-reactant to produce olefin macrocycles by ring expansion, or alternatively. The ring expansion of the cyclic olefin is provided by three types of sequential olefin metathesis (ring-opening, cross, and ring-closing olefin metathesis). More particularly, the invention pertains to synthesis of olefin macrocycles via olefin metathesis reactions using a Group 8 transition metal complex as the metathesis catalyst. Macrocycles provided herein have a variety of uses in the pharmaceutical, biomedical, organic synthesis and chemical industries, such as the production of crown ethers that are useful as metal complexing species.

Abstract: This invention relates to olefin polymerization processes for polymerizing ethylene, higher alpha-olefin comonomer and dienes, especially vinyl norbornene, and especially process for producing amorphous or semi-crystalline polymers such as EPDM. The invention also relates to the novel polymers produced by such processes. The invention furthermore relates to articles of manufacture with an improved balance of toughness and curing properties.

Abstract: A process for forming a coordination catalyst system comprising substantially simultaneously contacting: (I) pre-catalyst reactants comprising (a) at least one first ligand; and (b) at least one first transition metal suitable to form at least one metallocene or constrained geometry pre-catalyst compound (e.g., rac-ethylene bis(indenyl)zirconium dichloride); and optionally (c) at least one second ligand and (d) at least one second transition metal suitable to form at least one non-metallocene, non-constrained geometry, bidentate or tridentate transition metal compound (e.g., tridentate 2,6-diacetylpyridine-bis(2,4,6-trimethylanaline)FeCl2); and (II) further contacting, jointly or individually, the pre-catalyst compound(s) and optional bidentate or tridentate compound(s) with at least one support-activator agglomerate (e.g., spray dried silica/clay agglomerate). When individually contacted, the supported catalyst components can be mixed or blended.

Abstract: The present invention is a method for predicting polymer latex properties for an emulsion polymer latex based on statistical relationships between the polymer latex properties and process parameters for the emulsion polymerization process.

Abstract: A butadiene polymer (i) having a cis bond unit content of at least 50% based on the total butadiene units, a number average molecular weight (Mn) of 1,000 to 10,000,000, and at least 80%, based on the total molecular chains, of living chains containing a transition metal of group IV of the Periodic table at a terminal thereof; a polymer (ii) obtained by modifying terminals of the polymer (i); and a polymer (iii) obtained by coupling the polymers (i). These polymers (i), (ii) and (iii) are obtained by polymerizing a conjugated diene monomer alone or with a copolymerizable monomer at a specific temperature in the presence of a catalyst comprising a compound (A) of a transition metal of group IV of the periodic table having a cyclopentadienyl structure and a co-catalyst (B) selected from organoaluminum-oxy compound (a) and others and optionally further by contacting the resultant polymer with a terminal modifier or a coupling agent.

Abstract: A molding composition comprising a (co)polymer of vinylcyclohexane is disclosed. The copolymer is characterized in having an absolute molecular weight Mw of 100,000 to 450,000 g/mol, polydispersity index of 1 to 3 and maximum melt viscosity of 1000 Pa·s, as measured at 300° C. and at a shear rate of 1000 sec−1. The composition is suitable for producing a variety of molded article most notably optical data storage media.

Abstract: The present invention relates to a process for obtaining a polyisoprene having a high cis-1,4 linkage content, from a steam-cracked C5 naphtha fraction enriched with isoprene. The process of the present invention comprises reacting a steam-cracked C5 naphtha fraction in the presence of a catalytic system, wherein the C5 fraction is enriched with isoprene such that the mass fraction of isoprene in said enriched fraction lies within a range of from 30% to 95%, and the catalytic system is based on at least (a) a conjugated diene monomer, (b) an organic phosphoric acid salt of one or more rare earth metals, (c) an alkylating agent consisting of an alkylaluminum of the formula AlR3 or HAlR2, and (d) a halogen donor consisting of an alkylaluminum halide, said salt being suspended in at least one inert saturated hydrocarbon solvent of aliphatic or alicyclic type which is included in said catalytic system, and the molar ratio of alkylating agent: rare earth salt is in a range of from 1 to 5.

Abstract: The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b1) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a free radical initiator or b2) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, the (co)polymers obtainable by this process and the use of multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in combination with a free radical initiator, or a multi-functional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled polymerization.

Abstract: The present invention provides a process for preparing amino functionalized diene polymers with 1,4-trans linkage content equal to or greater than 70%. The invention also concerns polymers of such type, a rubber composition and a tire casing containing those polymers. The process of preparation according to the invention comprises polymerizing at least one diene monomer by means of a lithium catalytic system, which comprises at least one hydrocarbon solvent, one compound A of a IIIA group metal, one compound B of an alkaline earth metal and one aminolithium initiator C. Amino functionalized diene polymers with high 1,4-trans linkage content according to the invention are such that the amino function, situated at the end of the polymer chain, is a tertiary amino function, the rate of functionalization of said polymers being equal to or greater than 50% and the 1,4-trans linkage content being equal to or greater than 70%.

Abstract: An ambient dry water dispersed coating composition substantially free of volatile organic coalescing solvents, the coating composition containing a polymer film forming binder comprises between 40% and 50% copolymerized non-conjugated, unsaturated fatty acid triglyceride, between 40% and 55% copolymerized ethylenic monomer including styrene, and between 3% and 12% copolymerized maleic anhydride. The film forming copolymer is produced by first reacting maleic anhydride with the fatty acid triglyceride at high temperatures between 140° C. to form a maleinized triglyceride having a pendent maleic anhydride structure. The maleinized triglyceride is then styrenated at temperatures between about 80° C. and 200° C. in the presence of at least 4% peroxide initiator based on the weight of monomers copolymerized to form a styrenated, maleinized fatty acid triglyceride copolymer having anhydride groups.

Abstract: (1) A methacrylic ester or an acrylic ester is anionically polymerized, using a polymerization initiator compound comprising an addition reaction product of a conjugated diene compound and an organic alkali metal compound, in the presence of a tertiary organoaluminum compound having in the molecule thereof a chemical structure represented by a formula: Al—O—Ar wherein Ar represents an aromatic ring; or

Abstract: Methods and compositions for inhibiting the polymerization of vinyl monomers are disclosed. Combinations of aminophenol compounds and nitroxyl radical compounds are effective at inhibiting vinyl monomer polymerization under both processing and storage conditions.

Abstract: The ethylenic copolymer rubber according to the present invention is a novel and useful ethylenic copolymer rubber which can be cross-linked at a high velocity and is superior in scorching stability, in workability and in moldability, of which cross-linked product is superior in the mechanical properties, such as the cross-linked rubber strength etc., and in the form-preservability. A cross-linkable rubber composition containing this ethylenic copolymer rubber is utilized for producing, for example, cross-linked molded rubber product for use as sealing element and automobile weather strip sponge.

Abstract: The present invention provides a process for preparing amino functionalized diene polymers with 1,4-trans linkage content equal to or greater than 70%. The invention also concerns polymers of such type, a rubber composition and a tire casing containing those polymers. The process of preparation according to the invention comprises polymerizing at least one diene monomer by means of a lithium catalytic system, which comprises at least one hydrocarbon solvent, one compound A of a IIIA group metal, one compound B of an alkaline earth metal and one aminolithium initiator C. Amino functionalized diene polymers with high 1,4-trans linkage content according to the invention are such that the amino function, situated at the end of the polymer chain, is a tertiary amino function, the rate of functionalization of said polymers being equal to or greater than 50% and the 1,4-trans linkage content being equal to or greater than 70%.

Abstract: Elastic ethylene polymers are disclosed which have, processability similar to highly branched low density polyethylene (LDPE), but the strength and toughness of linear low density polyethylene (LLDPE). The polymers have processing indices (PI's) less than or equal to 70 percent of those of a comparative linear ethylene polymer and a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a traditional linear ethylene polymer at about the same I2 and Mw/Mn. The novel polymers can also have from about 0.01 to about 3 long chain branches/1000 total carbons and have higher low/zero shear viscosity and lower high shear viscosity than comparative liner ethylene polymers. T novel polymers can also be characterized as having a melt flow ratio, I10/I2,≧5.63, a molecular weight distribution, Mw/Mn, defined by the equation: Mw/Mn≦(I10/I2)−4.

Abstract: A process for making an allylic copolymer is disclosed. The process is a free radical copolymerization of an aqueous dispersing agent and a monomer mixture comprising a mono-ethylenic monomer, a multi-ethylenic monomer, and a mono-allylic monomer. The preferred aqueous dispersing agent is water. The copolymer produced has a high molecular weight and a broad molecular weight distribution, and it is particularly useful as a toner resin.

Abstract: A process for preparing a butyl polymer, the process comprising contacting a C4 to C8 monoolefin monomer with a C4 to C14 multiolefin monomer at a temperature in the range of from about −100° C. to about +50° C. in the presence of a diluent and a catalyst mixture comprising a monoalkylaluminum dihalide and an aluminoxane.

Abstract: The present invention relates to partially branched polymers having a number-average molecular weight Mn in the range from 500 to 20 000 daltons and synthesized from ethylenically unsaturated monomers including:

Abstract: The neodymium catalyst system prepared by the technique of this invention can be used in the polymerization of isoprene monomer into polyisoprene rubber that is clear (transparent) and of high purity. This invention more specifically discloses a process for the synthesis of polyisoprene rubber which comprises polymerizing isoprene monomer in the presence of a neodymium catalyst system, wherein the neodymium catalyst system is prepared by (1) reacting a neodymium carboxylate with an organoaluminum compound in the presence of isoprene for a period of about 10 minutes to about 30 minutes to produce neodymium-aluminum catalyst component, and (2) subsequently reacting the neodymium-aluminum catalyst component with a dialkyl aluminum chloride for a period of at least 30 minutes to produce the neodymium catalyst system.