Abstract: This invention reveals a pneumatic tire having an outer circumferential tread wherein said tread is a sulfur-cured rubber composition comprised of, based on 100 parts by weight of rubber, (1) from about 5 to about 50 parts of 3,4-polyisoprene rubber, wherein said 3,4-polyisoprene rubber has (a) a 3,4-isomer content of from 75 percent to 95 percent, (b) a 1,2-isomer content of from 5 percent to 25 percent, (c) a glass transition temperature from 0.degree. to 25.degree. C. and (d) a number average molecular weight which is within the range of 30,000 to 180,000; and (2) from about 50 to about 95 parts of a rubbery polymer which is co-curable with the 3,4-polyisoprene rubber.

Abstract: This invention reveals an initiator system which is comprised of (a) a lithium initiator, (b) a sodium alkoxide, and (c) a polar modifier; wherein the molar ratio of the sodium 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 sodium alkoxide to the lithium initiator is within the range of about 0.01:1 to about 20:1.

Abstract: A method is disclosed for processing a rubber composition comprising thermomechanically mixing at a rubber temperature in a range of 140.degree. C. to 190.degree. C. for a mixing time of 1 to 20 minutes(i) 100 parts by weight of at least one sulfur vulcanizable elastomer selected from conjugated diene homopolymers and copolymers, natural rubber and copolymers of at least one conjugated diene and aromatic vinyl compound;(ii) 10 to 250 phr of particulate precipitated silica;(iii) 0.01 to 1.0 parts by weight per weight of said silica of an organosilicon compound; and(iv) 0.05 to 10 phr of sodium thiosulfate pentahydrate.Addition of the sodium thiosulfate pentahydrate to sulfur vulcanizable rubber, silica and sulfur containing organosilicon compound decreases the mixing/processing time without sacrificing end product properties.

Abstract: The invention relates to a tire with a tread which is quantitatively reinforced with silica where the tread is composed of cis 1,4-polybutadiene rubber, a high vinyl polybutadiene rubber and, optionally a medium vinyl polybutadiene rubber. In one aspect, the tread rubber can also contain a minor amount of cis 1,4-polyisoprene natural rubber.

Abstract: The subject invention discloses an isoprene-butadiene diblock rubber which is particularly valuable for use in making treads for tires which have improved wear characteristics without compromising traction characteristics or rolling resistance. Said isoprene-butadiene diblock rubber is comprised of (1) a first block which is comprised of repeat units which are derived from 1,3-butadiene and (2) a second block which is comprised of repeat units which are derived from both 1,3-butadiene and isoprene, wherein the repeat units derived from isoprene and 1,3-butadiene in the second block are in an essentially random order, wherein the diblock rubber has a glass transition temperature which is within the range of about -100.degree. C. to about -70.degree. C., and wherein the diblock rubber has a Mooney viscosity which is within the range of about 50 to about 140.

Abstract: The subject invention relates to a technique for synthesizing rubbery copolymers of styrene and isoprene. These rubbery copolymers exhibit an excellent combination of properties for utilization in tire tread rubber compounds. By utilizing these styrene-isoprene rubbers in tire treads, tires having improved wet skid resistance can be built without sacrificing rolling resistance or tread wear characteristics.

Abstract: This invention reveals a high performance polybutadiene rubber blend comprised of (a) a first polybutadiene rubber, (b) a second polybutadiene rubber, and (c) a third polybutadiene rubber; wherein the first polybutadiene rubber, the second polybutadiene rubber, and the third polybutadiene rubber are selected from the group of consisting of super-high vinyl polybutadiene rubbers having a vinyl content which is within the range of 80 percent to 100 percent, high vinyl polybutadiene rubbers having a vinyl content which is within the range of 60 percent to 79 percent, medium vinyl polybutadiene rubbers having a vinyl content which is within the range of 35 percent to 59 percent, and low vinyl polybutadiene rubbers having a vinyl content which is within the range of 8 percent to 34 percent; wherein at least three members selected from the group consisting of super-high vinyl polybutadiene rubbers, high vinyl polybutadiene rubbers, medium vinyl polybutadiene rubbers, and low vinyl polybutadiene rubbers are included

Abstract: A rubber composition comprised of elastomer, silica, a silica coupler, sulfur and, optionally, carbon black, in which the silica, silica coupler and at least a portion of the sulfur are added in a non-productive mix stage.Pneumatic tires having treads comprised of such rubber composition are provided.

Abstract: A rubber composition comprised of elastomer, silica, a silica coupler, 2-mercaptobenzothiazole and, optionally, carbon black, in which the silica, silica coupler and at least a portion of the 2-mercaptobenzothiazole are added in a non-productive mix stage.Pneumatic tires having treads comprised of such rubber composition are provided.

Abstract: Pneumatic rubber tire with a tread composed of a rubber blend of a base of at least two synthetic elastomers composed of (i) specialized isoprene/butadiene copolymer elastomer having a low Tg in a range of about -70.degree. to about -100.degree. C. and (ii) a diene based elastomer having a Tg in a range of about -5.degree. to about -30.degree. C. together with a minor amount of natural cis 1,4-polyisoprene rubber. Selection of the base of the said two synthetic elastomers having spaced apart, or spatially defined, Tg's of at least 40.degree. C. is an important feature of the tread rubber blend. Representative examples of contemplated elastomers with Tg's in a range of about -5.degree. to about -30.degree. C. are 3,4-polyisoprene elastomer, styrene/isoprene copolymer elastomer and high vinyl polybutadiene elastomers.In one aspect, the tread rubber blend is reinforced with reinforcing filler composed of carbon black or a combination of carbon black and silica accompanied by a coupling agent.

Abstract: The subject invention relates to a technique for synthesizing rubbery copolymers of styrene and isoprene. These rubbery copolymers exhibit an excellent combination of properties for utilization in tire tread rubber compounds. By utilizing these styrene-isoprene rubbers in tire treads, tires having improved wet skid resistance can be built without sacrificing rolling resistance or tread wear characteristics.

Abstract: Metals from Groups I and II and organometallic compounds thereof can be used to catalyze the polymerization of diene monomers into polymers. The polymers formed in such polymerizations are terminated with the metal used to catalyze the polymerization and are sometimes referred to as living polymers. Very useful blends of such polymers can be made by utilizing the process of the present invention.