| abstract |
(57) Abstract: The present invention relates to a block copolymer for constituting an elastomer matrix of a crosslinkable rubber composition having reduced hysteresis, a rubber composition used in a crosslinked state in a tire tread, a titer tread and A tire comprising the tire tread exhibiting reduced rolling resistance. The copolymer of the invention having n blocks (n = 2 or 3) comprises a diene elastomer wherein each of said blocks has a molar content of units derived from conjugated dienes of greater than 15%, wherein n = 2 or n When = 3, at least one block forms a chain end of the copolymer composed of polyisoprene, and the number average molecular weight M n1 of each of the polyisoprene end blocks is substantially 2,500 to 20,000 g / mol. And the number average molecular weight M n2 of blocks of the copolymer other than the respective polyisoprene end blocks is substantially 80,000 to 350,000 g / mol. |