Abstract: A process for preparing a functionalized polybutadiene is provided. The process comprises the following steps: a) homopolymerising butadiene with a catalytic system based on at least one preforming conjugated diene, a salt of one or more rare earth metals of an organic phosphoric acid, an aluminium-containing alkylating agent, an alkylaluminium halide; b) adding a polyfunctional compound to the pseudo-living elastomer formed in step (a); and c) adding a functionalizing agent to the mixture formed in step (b). The total molar amount of aluminium in the polymerization medium is such that the (aluminium/rare earth salt) molar ratio has a value between 1 and 5 and the polymerization is carried out at a temperature between 40° C. and 90° C. A functionalized polybutadiene that can be obtained by the process, and a rubber composition containing the functionalized polybutadiene is also provided.

Abstract: A process for preparing a functionalized polybutadiene is provided. The process comprises the following steps: a) homopolymerising butadiene with a catalytic system based on at least one preforming conjugated diene, a salt of one or more rare earth metals of an organic phosphoric acid, an aluminium-containing alkylating agent, an alkylaluminium halide; b) adding a polyfunctional compound to the pseudo-living elastomer formed in step (a); and c) adding a functionalizing agent to the mixture formed in step (b). The total molar amount of aluminium in the polymerization medium is such that the (aluminium/rare earth salt) molar ratio has a value between 1 and 5 and the polymerization is carried out at a temperature between 40° C. and 90° C. A functionalized polybutadiene that can be obtained by the process, and a rubber composition containing the functionalized polybutadiene is also provided.

Abstract: A modified diene elastomer having a good flow resistance, and imparting to a rubber composition containing the same a good compromise of hysteresis and abrasion properties and a satisfactory processing with a view to a tire application is provided. This modified elastomer comprises: a) at least 70% by weight of a linear diene elastomer predominantly functionalized in the middle of the chain by an alkoxysilane group, optionally partly or completely hydrolyzed to silanol, the alkoxysilane group optionally bearing another function capable of interacting with a reinforcing filler, the silicon atom of the alkoxysilane group lying in the main chain of the diene elastomer; b) more than 0 and up to 30% by weight of a star-branched diene elastomer, the Mooney viscosity of said modified diene elastomer varying from 50 to 80 and the glass transition temperature (Tg) thereof varying from ?100° C. to ?80° C.

Abstract: A modified diene elastomer having a good flow resistance, and imparting to a rubber composition containing the same a good compromise of hysteresis and abrasion properties and a satisfactory processing with a view to a tire application is provided. This modified elastomer comprises: a) at least 70% by weight of a linear diene elastomer predominantly functionalized in the middle of the chain by an alkoxysilane group, optionally partly or completely hydrolyzed to silanol, the alkoxysilane group optionally bearing another function capable of interacting with a reinforcing filler, the silicon atom of the alkoxysilane group lying in the main chain of the diene elastomer; b) more than 0 and up to 30% by weight of a star-branched diene elastomer, the Mooney viscosity of said modified diene elastomer varying from 50 to 80 and the glass transition temperature (Tg) thereof varying from ?100° C. to ?80° C.

Abstract: A multicomponent preformed catalytic system based at least: on isoprene; on a rare earth metal salt of an organic phosphoric acid or of a carboxylic acid; on a saturated or unsaturated inert hydrocarbon solvent, the boiling point of which is below 40° C. at atmospheric pressure; on an alkylating agent consisting of a specific trialkylaluminium; and on a halogen donor consisting of an alkylaluminium halide. This catalytic system comprises the rare earth metal in a concentration greater than or equal to 0.005 mol/l. The catalytic system makes possible polymerizing isoprene, with a good catalytic activity, in solution in a volatile hydrocarbon solvent while benefiting from the economic advantage linked to a volatile solvent process, which is also a subject of the invention. The diene elastomers obtained have a high content of cis-1,4 linkages.

Abstract: A multicomponent preformed catalytic system based at least: on isoprene, on a rare earth metal salt of an organic phosphoric acid or of a carboxylic acid; on a saturated or unsaturated inert hydrocarbon solvent, the boiling point of which is below 40° C. at atmospheric pressure; on an alkylating agent consisting of a specific trialkylaluminium; and on a halogen donor consisting of an alkylaluminium halide; this catalytic system comprising the rare earth metal in a concentration greater than or equal to 0.005 mol/l. The catalytic system makes possible polymerizing isoprene, with a good catalytic activity, in solution in a volatile hydrocarbon solvent while benefiting from the economic advantage linked to a volatile solvent process, which is also a subject of the invention. The diene elastomers obtained have a high content of cis-1,4 linkages.