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AssigneesMichelin Recherche et Technique S.A., Compahnie Generale des Establissements Michelin
InventorsJean-Marc Marechal, Philippe Chaboche, Jean-Michel Favrot
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The present invention relates to a monomodal coupled diene elastomer having a silanol functional group in the middle of the chain, to its process of preparation and to a rubber composition which can be used in particular in the manufacture of tire covers, having improved hysteresis and physical properties in the vulcanized state and an improved processing in the raw state, comprising a monomodal diene polymer having a silanol functional group in the middle of the chain and a reinforcing inorganic filler. The process for obtaining this elastomer having a silanol functional group in the middle of the chain comprises a reaction of the diene monomer(s) and of the polymerization initiator in the presence of a chelating polar agent, a reaction of the living diene polymer with a coupling agent and then, after hydrolysis, a recovery of the coupled diene polymer having a functional group in the middle of the chain. A rubber composition according to the invention comprises a reinforcing inorganic filler and this monomodal elastomer having a silanol functional group in the middle of the chain.
Coupled diene elastomer having a silanol functional group, wherein it comprises a silanol functional group in the middle of the chain, an overall level of Si functional group L (which is the ratio Ns/Np, in which Ns represents the number of moles of silicon bonded to the coupled polymer, determined by 1H nuclear magnetic resonance NMR and expressed in mmol/kg, and Np represents the number of mmoles of polymer before coupling per kilogram of polymer) ranging from 0.36 to 0.60, a level of silanol functional group (SiOH) in the middle of the chain L1, which is the ratio corresponding to the number of moles of SiOH functional groups to the number of moles of silicon (Si), determined by 2D 1H-29Si nuclear magnetic resonance NMR, ranging from 80 to 100% and a monomodal distribution of the number-average molecular weights of the coupled polymer chains.
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