BLOCK COPOLYMERS OF DIENE HAVING THEIR TERMINAL END BLOCKS OF A RANDOM COPOLYMER OF STYRENE OR ALKYLSTYRENE AND AN ALPHA-METHYLSTYRENE, AND THEIR PREPARATION

摘要

Block copolymers are prepared having end blocks with random copolymer of styrene and/or alkyl substituted derivatives and alpha-methylstyrene ranges from 1:0.5 to 1:2.5, a central block of a polydiene polymer joins the terminal blocks. The block copolymers contain from 10 to 90 weight percent of polydiene, the remaining portion being of random (alkyl) styrene-alpha-methylstyrene copolymer. The polymers range from medium impact polystyrene type polymer of low polydiene content to thermoplastic elastomers of high polydiene content.