Abstract: The present invention provides a method of forming a functionalized polymer. The method includes the steps of providing a living lithium polymer and terminating the polymer with an oxazoline compound selected from an organic halide oxazoline and a branched or unbranched vinyl oxazoline compound. The present invention also provides a compounded rubber article wherein carbon black is compounded with a terminated rubber that is the reaction product of a living lithium polymer and such oxazoline compounds.

Abstract: Conjugated diolefins, optionally in combination with other unsaturated compounds which may be copolymerised with the diolefins, are polymerised by performing the polymerisation of the diolefins in the presence of catalysts based on rare earth compounds, cyclopentadienes and organoaluminium compounds in the presence of aromatic vinyl compounds as the solvent at temperatures of −30 to +100° C.

Abstract: A process for producing polymers of &agr;-methylstyrene uses tin IV chloride as a polymerization initiator. Use of tin IV chloride as an initiator allows polymerization to proceed without purification of the monomer prior to processing. Polymerization can be carried out at ambient temperatures with mild exotherms and good polymer yields. The process uses solvents commonly found in a plant producing &agr;-methylstyrene.

Abstract: A combined linear and nonlinear polymer (i.e., having a combined linear, branched and radial structure) P+PnD according to the present invention is represented by (P+PnD)−+Li, where P is a polymer of a monovinyl aromatic monomer or a conjugated diene monomer; PD is a nonlinear polymer having a combined linear, branched and radial structure due to a multifunctional compound D bonded to the polymer P; n is an integer ranging from 2 to 10 and represents the average number of bonds between the monovinyl aromatic or conjugated diene polymer P and the multifunctional compound D; and +Li represents a metal ion as a partner of the active anion (P+PnD)−. The combined linear and nonlinear polymer of the present invention, characterized by nonlinearity-related properties (i.e.

Abstract: This invention is based upon the discovery of certain anionic initiator systems can be used to initiate the solution polymerization of conjugated diolefin monomers into rubbery polymers having a low vinyl content. For instance, such initiator systems can be used in the copolymerization of styrene and isoprene to produce low vinyl styrene-isoprene rubber having a random distribution of repeat units that are derived from styrene. These initiator systems are comprised of (a) a lithium initiator and (b) a member selected from the group consisting of (1) a sodium alkoxide, (2) a sodium salt of a sulfonic acid, and (3) a sodium salt of a glycol ether. It is important for the initiator system to be free of polar modifiers, such as Lewis bases.

Abstract: The invention relates to a new process for the preparation of functionalized telechelics based on vinyl polyrners, the telechelics prepared in this way and their use in the plastics, fibers or coating sector.

Abstract: This invention is based upon the discovery that rubbery polymers having a high vinyl content and a low degree of branching can be synthesized with an initiator system that is comprised of (a) a lithium initiator selected from the group consisting of allylic lithium compounds and benzylic lithium compounds, (b) a Group I metal alkoxide, and (c) a polar modifier; wherein the molar ratio of the Group I metal alkoxide to the polar modifier is within the range of about 0.1:1 to about 10:1; and wherein the molar ratio of the Group I metal alkoxide to the lithium initiator is within the range of about 0.01:1 to about 20:1. These high vinyl polymers offer reduced levels of hysteresis and better functionalization efficiency.

Abstract: Insoluble, only slightly swellable popcorn polymers containing a) from 50 to 99% by weight of styrene and/or at least one monounsaturated styrene derivative, b) from 0.1 to 40% by weight of at least one N-vinyllactam or N-vinylamine and c) from 0.1 to 10% by weight of at least one difunctional crosslinking component, the stated percentages by weight of the individual components a) to c) summing to 100%.

Abstract: A tapered aromatic vinyl-conjugated diene copolymer rubber having a ratio W0.6Mp/WMp in the range of 0.65-0.9 or 1.1-1.3 wherein Mp is molecular weight of a copolymer molecule corresponding to the peak of a molecular weight distribution curve obtained by gel permeation chromatography, WMp is a weight fraction of aromatic vinyl monomer units in the copolymer molecule having a molecular weight Mp, and W0.6Mp is a weight fraction of aromatic vinyl monomer units in a copolymer molecule having a molecular weight of Mp×0.6. A coupled tapered rubber comprised of a plurality of tapered copolymer molecules which are bound together at molecule terminal. A rubber composition comprising this tapered rubber or coupled tapered rubber and natural rubber or a synthetic rubber. This rubber composition exhibits reduced heat build-up, and high wet skid resistance, tensile strength and abrasion resistance.

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 saturated 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: It is important for rubbery polymers that are used in tires, hoses, power transmission belts and other industrial products to have good compatibility with fillers, such as carbon black, silica, clay (including organoclays), and mixtures thereof. To attain improved interaction with fillers such rubbery polymers can be functionalized with various compounds, such as amines. The present invention discloses a process for synthesizing a rubbery polymer that is functionalized to attain improved compatibility with fillers.

Abstract: The present invention provides functionalized electrophiles, their analogous initiators, and processes for preparing these compounds. The present invention also relates to homotelechelic, heterotelechelic, and radial functional polydiene polymers, polyarylene polymers and polydiene/polyarylene copolymers, their optionally hydrogenated analogues, their optionally deprotected analogues, and processes for preparing these functionalized polymers.

Abstract: The present invention provides a process for the preparation of a diene elastomer having a reduced amount of vinyl linkages, by anionic polymerization of one or more monomers comprising at least one conjugated diene monomer. The process for preparing the diene elastomer having a reduced amount of vinyl linkages comprises anionically polymerizing one or more monomers comprising at least one conjugated diene monomer in a polymerization medium comprising a hydrocarbon solvent, a polar agent comprising one or more heteroatoms and a monolitiated or polylithiated organolithiated initiator, wherein an organometallic complex of the formula LiAl(R)3(R′), in which Li is a lithium atom, Al is an aluminum atom, and R and R′ are each an alkyl, cycloalkyl or aryl group, is added to the polymerization medium to produce the diene elastomer having a reduced amount of vinyl linkages.

Abstract: A cement composition comprising a polymeric latex prepared by aqueous emulsion polymerization of a monomeric mixture comprising styrene and butadiene in the presence of a seed polymer prepared by aqueous emulsion polymerization of styrene and a salt of 2-acrylamido-2-methylpropanesulfonic acid.

Abstract: A styrene random copolymer includes at least one unit of styrene derivative and at least one unit of macromonomer. The at least one unit of styrene derivative is polymerized from a styrene derivative monomer of formula (1). The at least one unit of macromonomer is polymerized from a macromonomer of formula (2). In formulae (1) and (2), R1 is selected from the group consisting of hydrogen, halogen, and alkyl groups with 1˜20 carbon atoms, R2 is at least one selected from the group consisting of saturated hydrocarbons with 1˜20 carbon atoms, aromatic groups, and cycloalkyl groups with the proviso that R2 is not —CO— or —CH2—C6H4—, R3 is a saturated hydrocarbon group with 1˜10 carbon atoms, X is at least one ion polymerizable monomer unit. The amount of the macromonomer is 0.

Abstract: This invention discloses an emulsion styrene-butadiene rubber (SBR) that can be employed in manufacturing tire tread formulations that have rolling resistance and treadwear characteristics that are similar to those made with solution SBR but with improved traction characteristics. Thus, the emulsion SBR of this invention is superior in many respects for use in tire tread compounds to conventional solution SBR and conventional emulsion SBR. This invention more specifically discloses a styrene-butadiene rubber composition which is comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein the styrene-butadiene rubber composition has a number average molecular weight as determined by thermal field flow fractionation which is within the range of about 50,000 to 150,000, and wherein the styrene-butadiene rubber has a light scattering to refractive index ratio which is within the range of 1.8 to 3.9.

Abstract: Disclosed are a phosphine derivative represented by formula (I): wherein Ar represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group, a transition metal complex comprising the phosphine derivative or a polymer thereof as a ligand, and a process for producing an optically active amino acid compound by asymmetric hydrogenation using the transition metal complex as a catalyst.

Abstract: This invention discloses an emulsion styrene-butadiene rubber (SBR) that can be employed in manufacturing tire tread formulations that have rolling resistance and treadwear characteristics that are similar to those made with solution SBR but with improved traction characteristics. Thus, the emulsion SBR of this invention is superior in many respects for use in tire tread compounds to conventional solution SBR and conventional emulsion SBR. This invention more specifically discloses a styrene-butadiene rubber composition which is comprised of repeat units which are derived from styrene, 1,3-butadiene, and a hydroxy alkyl acrylate monomer, wherein the styrene-butadiene rubber composition has a number average molecular weight as determined by field flow fractionation which is within the range of about 50,000 to 150,000, and wherein the styrene-butadiene rubber has a light scattering to refractive index ratio which is within the range of 1.8 to 3.9.

Abstract: The present invention provides resin materials for producing molded products endowed with excellent heat resistance, solvent resistance, toughness, tensile elongation, and transparency. Specifically, there are provided aromatic vinyl resin materials which have the following properties: Storage elasticity values G′(1.0) and G′(0.1) as measured at 300° C., a strain &ggr; of 20%, and a frequency of 1.0 Hz or 0.1 Hz satisfy the expression, log[G′(1.0)/G′(0.1)]≦0.6, the heat of fusion &Dgr;H as measured over the range 200-295° C. is 8 to 50 (J/g), and the 1H-NMR peak integrated values for the fraction corresponding to the temperature range of not lower than 50° C., as collected from temperature rising election fraction on the Soxhlet extraction residue by use of cyclohexane or o-dichlorobenzene, satisfy the relation [1.8-2.1 (ppm)]/[1.0-1.7(ppm))<0.49.

Abstract: A polymeric latex prepared by aqueous emulsion polymerization of a monomeric mixture comprising styrene and butadiene in the presence of a seed polymer prepared by aqueous emulsion polymerization of styrene and a salt of 2-acrylamido-2-methylpropanesulfonic acid.

Abstract: A process for reducing the odor emission of aqueous vinylaromatic/1,3-diene copolymer dispersions and of redispersion powders obtainable therefrom by drying, is by emulsion polymerization of a mixture containing at least one vinylaromatic and at least one 1,3-diene in the presence of one or more surfactant substances and optionally drying of the polymer dispersion obtained thereby. There are 0.01% to 15.0% by weight of one or more monomers of the branched or straight-chain alkyl esters having 1 to 8 C atoms in the alkyl radical of monounsaturated monocarboxylic or dicarboxylic acids and 0.01% to 15.0% by weight of one or more monomers based upon the vinyl esters of branched or straight-chain aliphatic carboxylic acids having 1 to 10 C atoms which are added in one step or in two successive steps toward the end of the polymerization, when the total content of free monomers in the aqueous copolymer dispersion is in the range from ≧0 to ≦20% by weight.

Abstract: A resin composition characterized by comprising from 5 to 95 wt % of an aromatic vinyl compound/olefin random copolymer (A) which has an aromatic vinyl compound content of from 1 to 99 mol % and has a head-to-tail chain structure composed of two or more aromatic vinyl compound units, and from 95 to 5 wt % of an &agr;-olefin type polymer (B) and/or an aromatic vinyl compound type polymer (C) (provided that it is neither a medical material nor a medical device), which contains substantially no chlorine and is excellent in the impact resistance, moldability, weather resistance and chemical resistance and which is useful for an injection molded product, an extrusion molded product, a film, a sheet, etc. Further, it provides an excellent damping material.

Abstract: The present invention is related to diimino compounds of formulae (I) R2—N═C(R1)(R3)nC(R1)═N—R2 and (II) (R1)2C═N—(CR24)m—N═C(R1)2 functionalized with at least one siloxy group. Said diimino compounds are useful for obtaining a solid catalyst component for polymerizing olefins wherein the diimino compound of formulae (I) or (II) is bonded to a porous inorganic support and to a transition metal selected from groups 8, 9 and 10 of the periodic table. This invention also relates to a process for preparing said diimino compounds of formulae (I) or (II), to a process for obtaining said solid catalyst component comprising the combination of the diimino compound and a porous inorganic support. Further, the invention also relates to the use of said solid catalyst in combination with a cocatalyst to polirnenrze olefins.

Abstract: A method of forming a polymer having reactive functionality comprises providing a reaction mixture comprising at least one monomer having at least one reactive functional group and carbon dioxide; and polymerizing the at least one monomer in the reaction mixture to form a polymer having reactive functionality associated with the at least one reactive functional group.

Abstract: Conventional SBR does not have the soft and smooth chew characteristics needed in chewing gum base for soft chew applications. Conventional SBR typically also has undesirable odor and taste characteristics that have generally limited its use in chewing gum base formulations. However, there is a desire to use SBR in such applications because it is relatively inexpensive. The present invention also specifically discloses a process for synthesizing styrene-butadiene rubber that is particularly useful in manufacturing chewing gum base for soft chew applications which comprises copolymerizing about 1 phm to about 12 phm styrene and about 88 phm to about 99 phm of 1,3-butadiene in an aqueous emulsion, wherein said copolymerization is conducted at a temperature which is within the range of about 1° C. to about 20° C.

Abstract: This invention relates to rubber polymers based on polymerizable monomers and having an elevated gel content together with an elevated degree of swelling, to the production of the stated rubber polymers and to the use thereof for the production of moldings of all kinds.

Abstract: The present invention concerns a method for the copolymerization of conjugated diolefins and vinyl-aromatic monomers in the presence of rare-earth catalysts and the use of the copolymers in rubber mixtures for tire applications.

Abstract: A conjugated diene polymer is produced by continuously polymerizing a conjugated diene monomer with a catalyst consisting essentially of components (1): a lanthanoid compound, (2): an aluminoxane and (3): a halogenated organometal compound, a halogenated metal compound or a halogenated organic compound in a hydrocarbon solvent containing 5-50% by weight of an aromatic hydrocarbon to obtain a conjugated diene polymer having a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of not more than 4.

Abstract: A process for the reaction of an organic compound in the presence of a catalyst comprising, as active metal, ruthenium alone or together with at least one Group Ib, VIIb, or VIIIb metal in an amount of from 0.01 to 30 wt %, based on the total weight of the catalyst, applied to a support, wherein from 10 to 50% of the pore volume of the support comprises macropores having a pore diameter in the range of from 50 nm to 10,000 nm and from 50 to 90% of the pore volume of the support comprises mesopores having a pore diameter in the range of from 2 to 50 nm, the sum of said pore volumes being 100%, and said catalyst as such.

Abstract: The present invention provides a process for preparing a branched diene elastomer having a high proporation of starred chains comprising anionically polymerizing at least one conjugated diene monomer having 4 to 12 carbons in a polymerization medium comprising a hydrocarbon solvent, such as cyclohexane, and an organometallic initiator, such as n-butyllithium, wherein tris-(2,4-di-tert-butylphenyl)phosphite is added to the polymerization medium as a starring agent during or at the end of polymerization in an amount such that the molar ratio of the starring agent to the initiator is between 0.1 and 1.5, preferably between 0.2 and 0.5. The process produces a branched diene elastomer having a high proportion of starred chains. The elastomer can be a homopolymer, such as polybutadiene or polyisoprene or a copolymer, such as polystyrene/polybutadiene.

Abstract: Organosilicon compounds of general formula (I) R1R2R3Si—R4—S—Zn—S—R4—SiR1R2R3  (I) wherein R1, R2, R independently, represent H, a halogen, alkyl or alkoxy and R4 represents an alkylidene group, their preparation and their use in rubber mixtures.

Abstract: The present invention provides resin materials endowed with excellent heat resistance, solvent resistance, tensile elongation, toughness, and transparency. Specifically, there are provided an ethylene copolymer having a vinyl group attributed to a diene monomer in the molecular chain and comprising an aromatic vinyl monomer (A), ethylene (B) and a diene monomer (C), and an aromatic vinyl graft copolymer which is a graft copolymerization product of an aromatic vinyl monomer (H) and an ethylene copolymer macromer (I).

Abstract: A copolymer of cyclopentadiene and/or dicyclopentadiene and a vinyl-substituted aromatic compound. The copolymer has a softening point of from 60 to 130° C., a vinyl-substituted aromatic compound content of from 30 to 90% by weight, a bromine number of from 30 to 90 g/110 g, a number average molecular weight of from 400 to 1,000, and a weight average molecular weight/number average molecular weight (Mw/Mn) ratio of 2.5 or less, and a process for producing the same. The copolymer is useful in the production of a tackifier and an adhesive.

Abstract: Mercaptans are normally used as chain transfer agents in emulsion polymerizations. The mercaptans used in commercial applications are typically complex mixtures of hundreds of similar compounds having boiling points within a narrow range. The chain transfer activity of different mercaptans with such mixtures can vary substantially. To further complicate the situation, the distribution of various mercaptans can also vary substantially between lots of material obtained from commercial sources. Thus, consistent molecular weight control is typically difficult to attain in free radical emulsion polymerizations. This invention is based upon the unexpected discovery that dibenzyltrithiocarbonate will act as a pure compound to effectively and consistently control molecular weight in free radical emulsion polymerizations. The polydispersity of polymers made using dibenzyltrithiocarbonate as a molecular weight regulator is similar to that obtained using conventional mercaptan systems.

Abstract: An oil extended rubber comprising 100 parts by weight of (A) an amino group-containing copolymer rubber of a conjugated diolefin and an aromatic vinyl compound which contains bonded amino groups in the amount of 0.0025-0.20 mmol/g polymer, and 10-100 parts by weight of (B) an extensible oil. Carbon black, silica, a mixture of carbon black and silica, or a carbon-silica dual-phase-filler can be homogeneously dispersed in the oil extended rubber. Vulcanized products obtained by vulcanizing the rubber exhibits well-balanced improved properties such as wet skid properties, low hysteresis loss properties, abrasion resistance, and breaking strength, and are useful as a tread material for low fuel consumption tires, large tires, and high performance tires.

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

Abstract: The process and catalyst system of this invention can be utilized to synthesize a highly random styrene-butadiene rubber having a high trans content by solution polymerization. The styrene-butadiene rubber made by the process of this invention can be utilized in tire tread rubbers that exhibit improved wear characteristics. This invention more specifically reveals a catalyst system for use in isothermal polymerizations which consists essentially of (a) an organolithium compound, (b) a calcium alkoxide and (c) a lithium alkoxide. The subject invention further discloses a process for synthesizing a random styrene-butadiene rubber having a low vinyl content by a process which comprises copolymerizing styrene and 1,3-butadiene under isothermal conditions in an organic solvent in the presence of a catalyst system which consists essentially of (a) an organolithium compound, (b) a calcium alkoxide and (c) a lithium alkoxide.

Abstract: In a process for the preparation of block copolymers from vinylaromatic monomers and dienes, the monomers are polymerized in the presence of at least one alkali metal organyl or alkali metal alkoxide and at least one magnesium, aluminum or zinc organyl.

Abstract: Star polymers obtainable by polymerization of vinylaromatic monomers with a branching monomer unit containing at least two vinylaromatic functional radicals in the presence of a catalyst obtainable from A) a transition-metal complex from sub-group II to VIII, B) a cation-forming agent and C), if desired, an aluminum compound.

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

Abstract: The present invention pertains to a substantially linear olefin polymer which has long chain branches, a high melt flow ratio, a narrow molecular weight distribution and critical shear rate at onset of surface melt fracture of a least 50 percent greater than the critical shear rate at the onset of melt fracture which is substantially higher than that of a linear olefin polymer having about the same molecular weight and molecular weight distribution. The novel polymer is an interpolymer of ethylene with at least one C3-C20 alpha-olefin and at least one unsaturated monomer.

Abstract: The present invention relates to a pneumatic tire having a tread containing from 50 to 100 phr of a dried rubber derived from a blend of a styrene butadiene latex and an acrylonitrile butadiene latex.

Abstract: A process for making an allylic copolymer is disclosed. The process is a free radical copolymerization of a mono-ethylenic monomer, a multi-ethylenic monomer, and a mono-allylic monomer. 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 conjugated diolefin copolymer rubber and a rubber composition which can produce vulcanized products exhibiting well-balanced improved properties such as wet skid properties, low hysteresis loss properties, abrasion resistance, and breaking strength irrespective of the types and combinations of fillers to be added, and is useful as a tread material for low fuel consumption tires, large tires, and high performance tires. A conjugated diolefin copolymer rubber is prepared by the copolymerization of a conjugated diolefin and a vinyl aromatic compound, and (1) has a content of the bonded vinyl aromatic compound of 5-50 wt %, (2) contains 0.01-5.0 mmol of an alkoxysilyl group having substantially non-hydrolyzable Si—O—R bond (wherein R indicates a hydrocarbon group having 4-20 carbon atoms) and 0.01-2.0 mmol of a tin-carbon bond for 100 g of the copolymer rubber, and (3) has a polymodal-type molecular weight distribution.

Abstract: A catalyst composition that is the combination of or the reaction product of ingredients including an iron-containing compound, a hydrogen phosphite, and a mixture of two or more organoaluminum compounds. This catalyst composition is particularly useful for polymerizing conjugated dienes. When this catalyst composition is used to polymerize 1,3-butadiene into syndiotactic 1,2-polybutadiene the ratio of the organoaluminum compounds can be adjusted to vary the melting temperature and molecular weight of the polymer product.

Abstract: Disclosed is a process for producing thermally stabilized styrenic polymers and products produced thereby wherein a pre-formed styrenic polymer is functionalized with a bifunctional Friedel-Crafts-type alkylation or acylation agent to yield a functionalized styrenic polymer. The functionalized polymer is admixed with a Friedel-Crafts-type catalyst, preferably a phosphate ester, and optionally a base, such that the functionalized polymer will experience inter- and intramolecular cross-linking reactions at elevated temperatures, thereby stabilizing the polymer from further thermal degradation.

Abstract: A new class of initiators for inducing the cationic polymerization of olefins was discovered. These initiators, in conjunction with Lewis acids as coinitiators, effectively initiate the carbocationic polymerization of olefins.

Abstract: A free radical polymerization process for the preparation of a thermoplastic resin or resins includes the in situ formation of a stable free radical agent from a precursor material in a reactor vessel, introducing a free radical initiator and at least one polymerizable monomer compound into the reactor vessel, and heating a mixture of the free radical initiator, the stable free radical agent, and the polymerizable monomer compound(s) in the reactor vessel to form a thermoplastic resin.

Abstract: This invention discloses a process for synthesizing random styrene-isoprene rubber comprising: (1) continuously charging isoprene, styrene, an initiator, and a solvent into a first polymerization zone, (2) allowing the isoprene and styrene to copolymerize in the first polymerization zone to total conversion of 60 to 95 percent to produce a polymer cement containing living styrene-isoprene chains, (3) continuously charging the polymer cement containing living styrene-isoprene chains and additional isoprene monomer into a second polymerization zone, wherein from 5 to 40 percent of the total amount of isoprene changed is charged into the second polymerization zone, (4) allowing the copolymerization to continue in the second polymerization zone to a conversion of the isoprene monomer of at least 90 percent wherein the total conversion of styrene and isoprene in the second polymerization zone is limited to a maximum of 98 percent, (5) withdrawing a polymer cement of random styrene-isoprene rubber having living cha

Abstract: Unsaturated copolymer which is a copolymer of an &agr;olefin of 2 to 12 carbon atoms and a conjugated diene monomer represented by the following formula (I-a) and has the properties: (a) in said copolymer, 1,2-addition units (including 3,4-addition units) derived from the conjugated diene monomer (I-a) form double bonds in the side chain of the copolymer, 1,4-addition units derived from the conjugated diene monomer (I-a) form double bonds in the main chain of the copolymer, and the quantity ratio of the double bonds of the side chain derived from the 1,2-addition units to the double bonds of the main chain derived from the 1,4-addition units (side chain double bonds derived from 1,2-addition units/main chain double bonds derived from 1,4-addition units) is in the range of 10/90 to 99/1 (b) five-membered rings are present in the main chain of said copolymer; and (c) the quantity ratio of the double bonds from all of the addition units to the five-membered rings (total of double bonds from all addition units/fi