The purpose is to provide rubber compositions and pneumatic tires which have reduced changes in tan δ peak temperature over time. The present invention relates to rubber compositions containing at least one copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound, the rubber compositions having a heat aging resistance index defined by equation (1) of 0.45 or less.

A resin composition comprises a prepolymer of crosslinking agent and benzoxazine resin and a maleimide resin. The resin composition may be used to make various articles, such as a prepreg, a resin film, a resin-coated copper, a laminate or a printed circuit board, and achieves improvements in at least one, more or all of the properties including laminate reflow shrinkage, T288 thermal resistance, ten-layer board T300 thermal resistance, dissipation factor, copper foil peeling strength, and resin filling property in open area.

A resin composition comprises a prepolymer of crosslinking agent and benzoxazine resin and a maleimide resin. The resin composition may be used to make various articles, such as a prepreg, a resin film, a resin-coated copper, a laminate or a printed circuit board, and achieves improvements in at least one, more or all of the properties including laminate reflow shrinkage, T288 thermal resistance, ten-layer board T300 thermal resistance, dissipation factor, copper foil peeling strength, and resin filling property in open area.

A resin composition comprises a prepolymer of crosslinking agent and benzoxazine resin and a maleimide resin. The resin composition may be used to make various articles, such as a prepreg, a resin film, a resin-coated copper, a laminate or a printed circuit board, and achieves improvements in at least one, more or all of the properties including laminate reflow shrinkage, T288 thermal resistance, ten-layer board T300 thermal resistance, dissipation factor, copper foil peeling strength, and resin filling property in open area.

A conjugated diene-based polymer of the present invention has an absolute molecular weight measured by viscosity detector-equipped GPC-light scattering measurement, of 40×10.sup.4 or more and 5000×10.sup.4 or less, has a branching number (Bn) measured by the viscosity detector-equipped GPC-light scattering measurement, of 8 or more, and has a modification ratio of 60% by mass or more.

A conjugated diene-based polymer of the present invention has an absolute molecular weight measured by viscosity detector-equipped GPC-light scattering measurement, of 40×10.sup.4 or more and 5000×10.sup.4 or less, has a branching number (Bn) measured by the viscosity detector-equipped GPC-light scattering measurement, of 8 or more, and has a modification ratio of 60% by mass or more.

The present invention refers to a polymer composite that comprises sand preferably medium, at least a load, at least a resin selected from among dicyclopentadiene polyester resin (DCPD) and resin PET and at least a phase-compatibilizing additive and/or flexibilizing agent of the polymer structure. Further, the present invention refers to process of preparing said composite besides the use of said composite for preparing some articles including sleepers. This composite presents several advantages when compared to the materials used today for preparing sleepers as it is more versatile than steel, more available and as effective as wood, more durable than the concrete as it comprises an optimized composition that combines ideal physical-chemical properties to exercise the function for which it was intended.

The present invention refers to a polymer composite that comprises sand preferably medium, at least a load, at least a resin selected from among dicyclopentadiene polyester resin (DCPD) and resin PET and at least a phase-compatibilizing additive and/or flexibilizing agent of the polymer structure. Further, the present invention refers to process of preparing said composite besides the use of said composite for preparing some articles including sleepers. This composite presents several advantages when compared to the materials used today for preparing sleepers as it is more versatile than steel, more available and as effective as wood, more durable than the concrete as it comprises an optimized composition that combines ideal physical-chemical properties to exercise the function for which it was intended.

The present invention relates to a a cross-linkable rubber composition, the cross-linkable rubber composition comprising, based upon parts by weight per 100 parts by weight rubber (phr): ≥60 phr to ≤80 phr of a butadiene rubber, a syndiotactic 1,2-polybutadiene, coupling agent, a filler, and a resin, wherein the composition co?prises ≥10 phr to ≤20 phr of the sy?diotactic 1,2-polybutadiene, and wherein the composition comprises ≥1 phr to ≤20 phr of at least two coupling agents wherein one of the coupling agents is or comprises a mercapto based silane and wherein the ratio of the mercapto based silane to the second coupling agent is in the range of ≥2:1 to ≤:10:1.

The present invention relates to a a cross-linkable rubber composition, the cross-linkable rubber composition comprising, based upon parts by weight per 100 parts by weight rubber (phr): ≥60 phr to ≤80 phr of a butadiene rubber, a syndiotactic 1,2-polybutadiene, coupling agent, a filler, and a resin, wherein the composition co?prises ≥10 phr to ≤20 phr of the sy?diotactic 1,2-polybutadiene, and wherein the composition comprises ≥1 phr to ≤20 phr of at least two coupling agents wherein one of the coupling agents is or comprises a mercapto based silane and wherein the ratio of the mercapto based silane to the second coupling agent is in the range of ≥2:1 to ≤:10:1.