| 摘要 |
"BLOCK COPOLYMER AND PROCESS FOR PREPARING IT" A linear copolymer constituted by four alternating blocks: B1-A1-B2-A2 wherein: B1 and B2 are polydienic blocks, and preferably polybutadiene blocks, and A1 and A2 are polyvinylaromatic, and preferably polystyrene blocks; which polymer has a weight average molecular weight of from 30,000 to 250,000, and a global content of monomer dienic units of from 40 to 80% by weight, wherein the weight average molecular we;ght of B1 block is comprised within the range of from 0.1 to 0.5 times the weight average molecular weight of B2 block, and the weight average molecular weight of A1 block is comprised within the range of from 0.25 to 2.0 times the weight average molecular weight of A2 block, and which contains between B1 and A1 blocks a copolymeric moiety formed by randomly linked monomer dienic and vinylaromatic units; is endowed with a desired balance of mechanical characteristics, rheologic characteristics and characteristics of thermooxidative resistance. The process to prepare such a block copolymer is disclosed. |
