TAPERED BLOCK COPOLYMERS OF CONJUGATED DIENES AND MONOVINYLARENES

摘要

A method for preparing tapered block copolymers in a polymerization process by sequentially charging: (1) an initiator and monovinylaromatic monomers in the presence of a randomizer; (2) an initiator and a mixture of monovinylaromatic and conjugated diene monomers; (3) an initiator and a mixture of monovinylaromatic and conjugated diene monomers; and (4) a coupling agent to produce a polymodal tapered block copolymer. The copolymers are particularly useful for packaging applications which require good environmental stress crack resistance.