BLOCK COPOLYMERS FOR RUBBER COMPOSITIONS FOR USE IN TYRES

摘要

The invention concerns block copolymers for forming an elastomer matrix of a crosslinkable rubber composition with reduced hysteresis, said rubber composition which is useable in crosslinked state in a tyre running tread, said running tread and the tyre comprising it exhibits reduced running resistance. The inventive copolymer with n blocks (n = 2 or 3), each of the blocks comprising a diene elastomer whereof the mol ratio of units derived from conjugated dienes is higher than 15 %, and one of said blocks forming a chain end of said copolymer consisting of a polyisoprene, respectively for n = 2 or n = 3, is such that: the mean mole weight Mn1 of said or each end polyisoprene block substantially ranges between 2500 and 20000 g/mol and the mean mole weight Mn2 of said copolymer block which is different from said or each end polyisoprene block ranges substantially between 80000 g/mol and 350000 g/mol.