Abstract: Homopolymers of conjugated dienes and copolymers of conjugated dienes with vinyl aromatic compounds or with other conjugated dienes having improved properties and an elastomeric character are prepared by use of a catalytic composition which comprises (a) an organo-lithium initiator and (b) a tercatalyst system comprising (b.sub.1) a compound of barium or strontium or calcium, (b.sub.2) an organometallic compound of a metal of Group 2B or 3A of the Mendeleev periodic table of elements and (b.sub.3) an alkali metal alcoholate ether or amine.

Abstract: Homopolymers of conjugated dienes and copolymers of conjugated dienes with other conjugated dienes or with vinyl aromatic compounds having an elastomeric character are prepared by use of a catalytic system formed of the reaction product of (a) an organometallic compound of a metal of Group IIIA of the Mendeleev periodic table of elements with (b) at least one electron-donor compound containing at least one hetero-atom.

Abstract: Homopolymers of butadiene and copolymers of butadiene with vinyl aromatic compounds or with other conjugated dienes, which polymers have a high content of trans-1,4 linkages and a low content of 1,2 linkages, are prepared by use of a novel anionic catalytic composition which comprises (a) an organo-lithium initiator and (b) a cocatalyst system comprising a compound of barium or strontium and an organometallic compound of a metal of Group IIB or IIIA of the Mendeleev periodic table of elements.

Abstract: Process of homopolymerizing conjugated dienes or copolymerizing conjugated dienes either with each other or with vinyl aromatic compounds to form elastomeric products having simultaneously a high content of trans-1,4 linkages and a low content of 1,2 linkages.In accordance with the invention, the monomers are reacted in a reaction medium in the presence of an added catalytic composition comprising (a) an organo-lithium initiator and (b) a catalyst compound having one of the formulas:M.sup.2A [M.sup.3A R.sup.1 R.sup.2 R.sup.3 R.sup.4 ].sub.2 or M.sup.2A [M.sup.2B (R.sup.1).sub.4 ]in which M.sup.2A is a metal of Group 2A of the Mendeleev periodic table of elements; M.sup.3A is a metal of Group 3A of the Mendeleev periodic table of elements; M.sup.2B is a metal of Group 2B of the Mendeleev periodic table of elements; R.sup.1, R.sup.2 and R.sup.3 are alkyl or aralkyl radicals; and R.sup.4 is an alkyl radical or an aralkyl radical or the radical OR.sup.5 in which R.sup.5 is an alkyl radical or an aralkyl radical.

Abstract: A method for the anionic polymerization of unsaturated monomers involves effecting reaction in the presence of an organic derivative of a metal alumina hydride in an amount ranging from 0.01 to 5.0 mol percent based upon the amount of unsaturated monomer.

Abstract: A method of preparing copolymers of conjugated diene monomers and monovinylaromatic monomers having a random distribution of monomer units in the presence of a catalyst, metallic lithium in granules, and a modifying additive soluble in a reaction medium and consisting of reaction products of potassium or sodium carbonate, acetate or hydroxide with organoaluminum compound of the general formula:AlR'.sub.m R.sub.n, in which: R' -can be alkyl, aryl, aralkyl, group- OR'", -SR'" or -NR.sub.2 '"; R" - is alkoxy or aryloxy radicals; R'"- -can be hydrogen, alkyl, aryl, aralkyl; m and n - are integers from 0 to 3, inclusive, in case of the said carbonates and acetates, m - are integers from 0 to 2, inclusive, and n-are integers from 1 to 3, inclusive, in case of the said hydroxides. In the above mentioned product the ratio of g-atoms of aluminum per 1 g-atom of potassium or sodium can be from 2 to 20. Copolymerization is effected in solution in liquid hydrogen solvent over a temperature range from 0.degree. to 100.