Provided are a rubber composition having a good balance of improved fuel efficiency, abrasion resistance, and wet grip performance while providing good processability, and a pneumatic tire having a tread manufactured from the rubber composition. A rubber composition comprising: a copolymer synthesized by copolymerization of a conjugated diene monomer and an unsaturated acyclic monoester represented by the formula (1) below; and carbon black and/or silica, ##STR00001##
wherein R.sup.1 represents hydrogen or a C1-C30 hydrocarbon group, and R.sup.2 represents hydrogen or a C1-C30 hydrocarbon group.

Producing an isoprenoid compound by: 1) culturing an isoprenoid compound-forming microorganism in the presence of a growth promoting agent at a sufficient concentration to grow the isoprenoid compound-forming microorganism; 2) decreasing a concentration of the growth promoting agent to induce formation of the isoprenoid compound by the isoprenoid compound-forming microorganism; and 3) culturing the isoprenoid compound-forming microorganism to form the isoprenoid compound, is characterized in that the growth phase of the isoprenoid compound-forming microorganism is separated from the formation phase of the isoprenoid compound.

Producing an isoprenoid compound by: 1) culturing an isoprenoid compound-forming microorganism in the presence of a growth promoting agent at a sufficient concentration to grow the isoprenoid compound-forming microorganism; 2) decreasing a concentration of the growth promoting agent to induce formation of the isoprenoid compound by the isoprenoid compound-forming microorganism; and 3) culturing the isoprenoid compound-forming microorganism to form the isoprenoid compound, is characterized in that the growth phase of the isoprenoid compound-forming microorganism is separated from the formation phase of the isoprenoid compound.

A catalyst composition for selectively hydrogenating a conjugated diene polymer in a homogeneous system is provided, wherein the conjugated diene polymer comprises a conjugated diene monomer or a combination of a conjugated diene monomer and a vinyl aromatic monomer. The catalyst composition includes the catalyst components of (a) a titanium compound; (b) an organometallic compound; and (c) an oligomer containing a polyglycol segment. The hydrogenated polymer produced using the catalyst composition and the method thereof is also provided.

A catalyst composition for selectively hydrogenating a conjugated diene polymer in a homogeneous system is provided, wherein the conjugated diene polymer comprises a conjugated diene monomer or a combination of a conjugated diene monomer and a vinyl aromatic monomer. The catalyst composition includes the catalyst components of (a) a titanium compound; (b) an organometallic compound; and (c) an oligomer containing a polyglycol segment. The hydrogenated polymer produced using the catalyst composition and the method thereof is also provided.

The present invention is directed to a functionalized elastomer comprising the reaction product of a living anionic elastomeric polymer and a polymerization terminator comprising the reaction product of a polyol of formula I with an alkoxysilane of formula II ##STR00001##
where R.sup.1 and R.sup.2 are independently C1 to C10 alkyl; k is an integer from 2 to 4; n is an integer from 2 to 3, and n+m=4; with the proviso that when k=2 or 3, n=2 and when k=4, n=2 or 3.

A polymeric article comprises an elastomeric layer comprising cured synthetic polyisoprene particles that comprise a Ziegler-Natta catalyzed polyisoprene.

A polymeric article comprises an elastomeric layer comprising cured synthetic polyisoprene particles that comprise a Ziegler-Natta catalyzed polyisoprene.

A polymeric article comprises an elastomeric layer comprising cured synthetic polyisoprene particles that comprise a Ziegler-Natta catalyzed polyisoprene.

The present disclosure provides a polyisoprene wherein: a vinyl bond content of the polyisoprene is 30 mol % or higher; and a ratio of the weight-average absolute molecular weight (Mw′) determined by GPC-MALS with respect to the weight-average molecular weight (Mw) in terms of polystyrene determined by GPC, i.e., Mw′/Mw, is 0850 or less. A rubber composition containing the polyisoprene is excellent in the fuel-saving performance and grip performance on a wet road surface, as compared with a rubber composition containing the conventional polyisoprene.