Rubber composition

A polymer blend, comprising:

• (a) 50 to 95 percent by weight of a first elastomeric polymer,
• (b) 5 to 50 percent by weight of a second elastomeric polymer;
• wherein the first elastomeric polymer is a random polymer and obtainable by (I) anionic polymerization of at least one conjugated diene monomer and one or more α-olefin monomer(s) in the presence of a polymerization initiator in an organic solvent and (II) optionally coupling of the polymer chains obtained in (I) by a coupling agent;
• wherein the second elastomeric polymer is obtainable by (i) anionic polymerization of at least one conjugated diene monomer and one or more α-olefin monomer(s) in the presence of a polymerization initiator in an organic solvent, and (ii) coupling the polymer chains obtained in (i) by a coupling agent;
• wherein the first elastomeric polymer (a) has a number average molecular weight (Mn) of 300,000 to 2,000,000 g/mol and a weight-average molecular weight (Mw) of 300,000 to 4,000,000 g/mol;
• wherein the second elastomeric polymer (b) has a number average molecular weight (Mn) of 1,000 to 80,000 g/mol, a weight-average molecular weight (Mw) in the range of 1,000-140,000 g/mol and a molecular weight at the maximum of the peak (Mp) in the range of 2,000 g/mol to 100,000 g/mol;
• and
• wherein the amounts of the components (a) and (b) are based on the total weight of the polymer blend.