Rubber composition for dynamic or static applications, process for preparing same and products incorporating same

A crosslinkable rubber composition based on at least one elastomer, the composition comprising other ingredients which include a crosslinking system and a thermoplastic polymeric phase which has at least one melting temperature Tm and which is dispersed in said at least one elastomer in the form of nodules, the crosslinkable composition comprising the product:

• a) of a melt reaction by thermomechanical working of a reaction mixture comprising said at least one elastomer and said other ingredients, with the exception of the crosslinking system, to obtain a precursor mixture of the crosslinkable composition, then
• b) of mechanical working of said precursor mixture with prior addition of the crosslinking system to obtain the crosslinkable composition,
• wherein:
• the nodules have a weight-average greatest transverse dimension of between 150 nm and 3 μm,
• said reaction comprises heating of the reaction mixture up to a maximum compounding temperature Ta which is greater than the highest of said at least one melting temperature Tm of the thermoplastic polymeric phase and which is maintained for a holding time,
• the crosslinking system comprises sulfur when said at least one elastomer is unsaturated and said thermoplastic polymeric phase comprises saturated polymer chains, and comprises a peroxide when said at least one elastomer is saturated,
• when the crosslinking system comprises sulfur, said elastomer(s) is(are) an EPDM (Ethylene-Propylene-Diene Terpolymer) or natural rubber, and said thermoplastic polymeric phase is a polypropylene;
• and
• when the crosslinking system comprises a peroxide, said elastomer(s) is(are) a PDMS (Polydimethylsiloxanes), and said thermoplastic polymeric phase is a saturated polymer chosen from phenyl silicone resins:
• the holding time of said maximum compounding temperature Ta is of between 1 minute and 5 minutes, and
• the crosslinkable rubber composition comprises, as a powdered filler dispersed in said at least one elastomer, from 0 to 10 phr of carbon black and from 0 to 60 phr of a non-reinforcing inorganic filler other than a silica (phr:
• parts by weight per 100 parts of elastomer(s)).