Rubber composition ready for crosslinking

A ready-to-crosslink rubber-based composition, in the form of an extruded strip, said composition comprising:

• a) a total quantity of rubber of between 30% and 90% by weight or between 30% and 99% by weight;
• b) a rubber activating agent in an amount of between 0.1% and 10% by weight;
• c) a vulcanising agent which comprises sulphur, in an amount of between 0.5% and 5% by weight;
• characterised in that said ready-to-crosslink composition comprises a total amount of bound sulphur selected from one of at least 0.25% by weight, between 0.25% and 10% by weight, or between 0.25% and 5% by weight, and an amount of free sulphur of between 0.1% and 5% by weight, each aforementioned % by weight being expressed relative to the total weight of the composition.

A method for manufacturing a ready-to-crosslink rubber-based composition, to form an extruded strip, said method comprising the following steps:

• a) selecting a first fraction comprising at least 50% by weight of a vulcanised elastomer waste selected from the group consisting of ethylene-propylene-diene monomer (EPDM);
• styrene-butadiene (SBR), natural rubber (NR), synthetic isoprene (IR) and mixtures thereof, and wherein said vulcanised elastomer waste has a quantity of bound sulphur selected from one of at least 0.25% by weight, between 0.25% and 10% by weight, or between 0.25% and 5% by weight;
• b) devulcanisation by (thermo)chemical or (thermo)mechanical means of said first fraction to obtain a devulcanised material;
• c) optionally, selecting a second fraction comprising at least 30% by weight of a virgin elastomer selected from the group consisting of ethylene-propylene-diene monomer (EPDM), styrene-butadiene (SBR), natural rubber (NR), synthetic isoprene (IR) and mixtures thereof,
• d) optionally, adding said devulcanised material to said second fraction;
• e) mixing the material obtained in step b or step d, with at least one rubber activating agent and a vulcanising agent which comprises sulphur with formation of a devulcanised mixture corresponding to said ready-to-crosslink rubber-based composition;
• characterised in that said ready-to-crosslink rubber-based composition obtained during the mixing of step (e) comprises one of 0.25% by weight, between 0.25% and 10% by weight, or between 0.25% and 5% by weight of bound sulphur, and between 0.25 and 2% by weight of free sulphur, relative to the total weight of the composition.