Abstract: The present invention relates to a cross-linkable or cross-linked rubber composition having improved hysteresis properties in the cross-linked state which is useful for constituting a tire tread, to a process for preparation of such a cross-linkable composition, to a tread of this type and to a tire having reduced rolling resistance. The rubber composition according to the invention is based on: an elastomeric matrix comprising at least one diene elastomer which comprises a carboxylic acid function at one or at each of its two chain ends, and a reinforcing filler comprising a reinforcing inorganic filler, wherein said diene elastomer has a molecular weight which is greater than 80,000 g/mol, and it is present in a majority quantity in said elastomeric matrix.

Abstract: The present invention relates to a process for the preparation of a dilithiated initiator usable in anionic polymerization, a process for the preparation by anionic polymerization of a living diene elastomer which is provided with a carbon-lithium group at each of its chain ends, and a process for the preparation of a copolymer having three blocks starting from said living diene elastomer. The process for the preparation of a dilithiated initiator according to the invention involves of reacting a first reagent, a dialkenyl benzene, and a second reagent, secondary butyllithium, in the presence of a diamine, in an aliphatic or alicyclic hydrocarbon solvent, such that the ratio of the number of moles of first reagent to the number of moles of second reagent is substantially equal to 0.5, so that the initiator obtained is essentially a bi-adduct resulting from the addition of a molecule of secondary butyllithium to each of the two double bonds in the dialkenyl benzene.

Abstract: The present invention relates to a cross-linkable or cross-linked rubber composition having improved hysteresis properties in the cross-linked state which is useful for constituting a tire tread, to a process for preparation of such a cross-linkable composition, to a tread of this type and to a tire having reduced rolling resistance.

Abstract: The present invention relates to a process for carbonation of a living diene polymer obtained anionically. The carbonation process according to the invention is of the type consisting in spraying a solution of said polymer through at least one nozzle (5) into a chamber (2), in the form of droplets and in contact with carbon dioxide, into a bath which is substantially at rest filling said chamber (2) and formed of said carbon dioxide, such that said sprayed solution and said bath interact for said carbonation. This process is such that it consists in spraying said solution merely by the difference in hydrostatic pressure between the inlet to said or each nozzle (5) and the interior of said chamber (2).