PROCESS FOR THE PREPARATION OF POLYMERS OF CONJUGATED DIENES OR OF COPOLYMERS OF CONJUGATED DIENES WITH EACH OTHER OR WITH A VINYLAROMATIC COMPOUND

摘要

A process of preparing a bimodal or multimodal homopolymer of a conjugated diene or a bimodal or multimodal copolymer of a conjugated diene with another conjugated diene or with a vinyl aromatic compound consists in polymerizing the monomer(s) in a reaction medium at a temperature of between 20 DEG C. and 200 DEG C. in the presence of a catalyst system comprising an organolithium initiator, a barium, strontium or calcium compound, and an organometallic compound of a metal of group 2B or 3A of the periodic classification of elements of the Mendeleev Table, and adding to the reaction medium during the course of the polymerization reaction a compound of a transition metal of groups 1B to 7B and 8 or a magnesium compound of the general formula Mg(A)2.