| abstract |
There are disclosed novel, solid, elastomeric block copolymers with improved resistance to cold flow wherein either 1) the terminal blocks are polymers of at least one conjugated diene I, e.g., isoprene, which contains at least five carbon atoms with at least one of each pair of double-bonded carbon atoms in the polymerized diene I units being additionally single-bonded to two carbon atoms, at least one middle or interior block is a polymer of butadiene, and at least one middle or interior block is a polymer of at least one aryl-substituted olefin, e.g., styrene; or 2) the terminal blocks are random copolymers of at least one diene I as previously defined and butadiene, and at least one middle or interior block is a polymer of at least one aryl-substituted olefin. n The invention also encompasses the selective hydrogenation of the foregoing polymers such that substantially all of the residual double bonds of the polymerized butadiene units are hydrogenated while a sufficient number of polymerized I units remain unsaturated to provide a basis for subsequent vulcanization or cross-linking. |