Devulcanization of rubber and other elastomers
A process for forming a vulcanized elastomer composition. An alternating electric field is applied to a first composition comprising vulcanized crosslinked elastomer particles while the composition is compressed to thereby devulcanize the crosslinked elastomer particles and form a second composition comprising devulcanized elastomer particles A crosslinking agent is added to the second composition comprising the devulcanized elastomer particles. The second composition having the crosslinking agent is then vulcanized to form the vulcanized elastomer composition.
1. A process for forming a vulcanized elastomer composition, comprising:
applying an alternating electric field to a first composition comprising vulcanized crosslinked elastomer particles while said composition is compressed, said alternating electric field having a frequency and a voltage sufficient to devulcanize said crosslinked elastomer particles to form a second composition comprising devulcanized elastomer particles having substantially the same surface and interior properties;
adding a crosslinking agent to said second composition comprising said devulcanized elastomer particles; and
vulcanizing said second composition having said crosslinking agent to form said vulcanized elastomer composition.
2. The process of claim 1 wherein said frequency of said alternating electric field is about 1 MHz to 100 MHz, and wherein said voltage of said alternating electric field is about 1000 V to 10,000 V.
3. The process of claim 1 wherein said first composition comprises a vulcanized rubber.
4. The process of claim 3 wherein said vulcanized rubber has a particle size of 6 to 400 mesh.
5. The process of claim 1 wherein said first composition comprises vulcanized rubber particles and fresh unvulcanized rubber.
6. The process of claim 5 wherein said fresh unvulcanized rubber comprises at least 10 wt % of said first composition.
7. The process of claim 1 further comprising the step of adding fresh unvulcanized rubber to said second composition prior to said vulcanizing step.
8. The process of claim 7 wherein said fresh unvulcanized rubber comprises at least 10 wt % of said second composition.
9. The process of claim 1 further comprising the step of adding a filler to said second composition prior to said vulcanizing step.
10. The process of claim 1 wherein said crosslinking agent is sulfur or a sulfur donor.
11. The process of claim 1 further comprising the step of adding a vulcanization accelerator to said second composition prior to said vulcanizing step.
12. The process of claim 1 wherein said vulcanizing step comprises heating said second composition comprising said crosslinking agent and said devulcanized elastomer particles.
13. The process of claim 1 wherein said vulcanizing step comprising applying an alternating electric field to said second composition comprising said crosslinking agent and said devulcanized elastomer particles at a voltage and a frequency sufficient to vulcanize said devulcanized elastomer particles with said crosslinking agent.