Abstract: There is disclosed a process for the preparation of medium vinyl polybutadiene which comprises copolymerizing butadiene with small amounts of divinylbenzene in a hydrocarbon solvent system employing as a catalyst an alkyl lithium compound which has been modified by mixtures of polar compounds, at least one of which polar compound is selected from the group consisting of hexamethylphosphoric acid triamide (HMPA), N,N,N'N'-tetramethylethylene diamine (TMEDA), ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme) and tetraethylene glycol dimethyl ether (tetraglyme), and at least one of which polar compound is selected from the group consisting of tetrahydrofuran (THF), 1,4diazabicyclo [2.2.2] octane (DABCO), diethyl ether, triethylamine, tri-n-butylamine, tri-n-butylphosphine and p-dioxane, in which the temperature is maintained constant throughout the polymerization.

Abstract: A block polymer of an alkyl vinyl aromatic compound, conjugated diolefins and an alkyl-vinylpyridine with the central poly(diolefin) segment being branched by copolymerization with divinyl benzene to give a composition having improved 100 percent modulus, usually from 400 to 1400 pounds per square inch.

Abstract: A method of preparation and the composition of thermoplastic block polymers wherein divinylbenzene is added with the diolefin monomer to a polystyryllithium initiator to prepare a unique block polymer having good physical characteristics and low gel.