Abstract: The present invention provides a coupled polymer, which is prepared by reacting a living alkali metal-terminated polymer with a particular coupling agent. The coupling agent has the formula ##STR1## where R1, R3 are independently selected from the group consisting of aliphatic alkyl and alkenyl, and hydrogen, and R.sub.2 is alkylene, alkenylene, divalent cycloalkylene, divalent arenyl, or a C.sub.1-17 divalent hydrocarbyl containing ether or ketone group. By means of the particular coupling agent, the coupling efficiency is relatively high, and no harmful materials will be generated to corrode the pipes. The coupled polymer obtained has a coupling number of less than 3, and good rubbery physical properties, transparency, and wear resistance.

Abstract: The rubber for high-performance tire tread of the invention basically includes: (a) about 10%.about.50% weight percentage low molecular weight coupled copolymer of aromatic vinyl compound and conjugated diene or conjugated diene monopolymer, having a molecular weight of 5.times.10.sup.4 .about.35.times.10.sup.4, (b) about 10%.about.60% weight percentage middle molecular weight uncoupled copolymer of aromatic vinyl compound and conjugated diene, having a molecular weight of 10.times.10.sup.4 .about.80.times.10.sup.4, and (c) 5.about.60% weight percentage high molecular weight coupled copolymer of aromatic vinyl compound and conjugated diene, having a molecular weight of 45.times.10.sup.4 .about.200.times.10.sup.4.

Abstract: A process of preparing an elastomeric copolymer composition of mono-vinyl aromatic hydrocarbon and conjugated diene is disclosed. The composition produced by this process has preferred properties, i.e. the product possesses the characteristics of enhancing ultimate elongation up to 900%, keeping tensile strength in a suitable range and enhancing transparency.

Abstract: The present invention provides a process for selective hydrogenation of a conjugated diene polymer. The process includes bringing the conjugated diene polymer in an inert organic solvent into contact with hydrogen in the presence of a specific hydrogenation catalyst combination including (A) a substituted or unsubstituted bis(cyclopentadienyl) Group VIII transition metal compound and (B) an organic lithium compound. The hydrogenation can be carried out in the presence of a small amount of the hydrogenation catalyst combination under mild conditions, and both the hydrogenation conversion and selectivity to conjugated diene units are high.