Embodiments of the present disclosure are directed to functionalized copolymers produced by copolymerization of at least one conjugated diolefin monomer and at least one vinyl monomer, the functionalized copolymer comprising at least one functional group having silica reactive moieties, wherein the functionalized copolymer has a degree of hydrogenation of 75% to 98 mol % as measured using proton nuclear magnetic resonance spectroscopy (.sup.1H NMR).

A hydrogenated conjugated diene-based polymer of the present invention has a branch number (Bn) measured by viscosity detector-equipped GPC-light scattering measurement of 2.5 or more, and a hydrogenation rate of a structural unit derived from a conjugated diene compound of 30% or more and less than 99%.

The present invention aims to provide tire rubber composition with significantly improved overall performance in terms of wet grip performance and fuel economy, and pneumatic tires including the rubber compositions. The tire rubber compositions of the present invention have a tan δ versus temperature curve whose peak tan δ and half width satisfy the following relationship (1): Peak tan δ/Half width ≥ 0.025 (1).

There is disclosed a modified conjugated diene polymer including a structural unit derived from a compound represented by formula (1), and a structural unit derived from a conjugated diene.

##STR00001##

When n is 0, at least two of R.sup.11, R.sup.12, R.sup.13, R.sup.16, R.sup.17 and R.sup.18 are substituted amino groups, and at least one is a hydroxy group or hydrocarbyloxy group.

There is disclosed a modified conjugated diene polymer including a structural unit derived from a compound represented by formula (1), and a structural unit derived from a conjugated diene.

##STR00001##

When n is 0, at least two of R.sup.11, R.sup.12, R.sup.13, R.sup.16, R.sup.17 and R.sup.18 are substituted amino groups, and at least one is a hydroxy group or hydrocarbyloxy group.

A method for preparing a functionalized polymer, the method comprising the steps of: (i) polymerizing monomer to form a reactive polymer, and (ii) reacting the reactive polymer with an imine compound containing a heterocyclic group and a hydrocarbyloxy-substituted or silyloxy-substituted aryl group.

A method for preparing a functionalized polymer, the method comprising the steps of: (i) polymerizing monomer to form a reactive polymer, and (ii) reacting the reactive polymer with an imine compound containing a heterocyclic group and a hydrocarbyloxy-substituted or silyloxy-substituted aryl group.

A rubber composition according to an embodiment contains a diene rubber and silica. A change rate of a distance between aggregates represented by V50/V0 calculated by an inertia radius V50 of a silica aggregate and an inertia radius V0 of the silica aggregate is 1.30 or more. The inertia radius V50 is obtained by performing a small-angle X-ray scattering measurement in a state where a vulcanized rubber obtained by vulcanizing the rubber composition is elongated by 50%, and the inertia radius V0 is obtained by performing a small-angle X-ray scattering measurement in a state where the vulcanized rubber is not elongated.

A resin-extended elastomer comprises an elastomer which is a synthetic diene elastomer with a number-average molar mass of greater than or equal to 200,000 g/mol and a resin which is a plasticizing hydrocarbon-based resin. A process for obtaining such a resin-extended elastomer and compositions, semi-finished products for tires and tires containing same are also disclosed.

A resin-extended elastomer comprises an elastomer which is a synthetic diene elastomer with a number-average molar mass of greater than or equal to 200,000 g/mol and a resin which is a plasticizing hydrocarbon-based resin. A process for obtaining such a resin-extended elastomer and compositions, semi-finished products for tires and tires containing same are also disclosed.