Patent ID: 8067503

Claim:
A tire sidewall composition comprising a blend of syndiotactic 1,2-polybutadiene and an elastomeric terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer, wherein said blend is prepared by: a. providing a mixture of a rubber cement and 1,3-butadiene monomer, wherein the rubber cement comprises an elastomeric terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer; and b. polymerizing the 1,3-butadiene monomer into syndiotactic 1,2-polybutadiene within the rubber cement by using a catalyst composition that is formed by combining (a) a chromium-containing compound, (b) a hydrogen phosphite, and (c) an organomagnesium compound or (a) a molbydenum-containing compound or an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound; wherein the composition is incorporated in a tire sidewall; wherein the blend of syndiotactic 1,2-polybutadiene in said terpolymer comprises from about 3 percent to about 12 percent by weight of syndiotactic 1,2-polybutadiene, wherein a test sheet of the composition has a cut growth of 45 Dc/Dn (nm/cycle) and below at 50° C.