Patent ID: 8304459

Claim:
A method for breaking chemical cross links in vulcanised rubber materials to create de-vulcanised rubber, the method comprising: treating a vulcanised rubber material with a supercritical fluid maintained at supercritical pressure and temperature to cause swelling of the said vulcanized rubber material, and subsequently rapidly reducing the supercritical fluid pressure to a controlled pressure level to cause vaporization of said supercritical fluid, thereby rapidly expanding the vulcanised rubber material beyond the restraining capability of the chemical cross links, but within the extendable limits of the long chained molecular backbone of the rubber, thereby causing preferential breakage of the chemical cross links while maintaining the integrity and molecular weight of the rubber molecules, wherein the rapid reduction of the supercritical pressure takes place over a timescale of greater than 0.5 seconds and less than 60 seconds, and wherein the rate and extent of the rapid reduction of the supercritical fluid pressure are controlled to obtain breaking of sulphur-containing linkages in the vulcanized rubber material without explosive decompression thereof.