Abstract: The present invention relates to a method for preferentially breaking cross-links in a vulcanized rubber, thereby de-vulcanizing the rubber, by the use of a supercritical fluid, such as carbon dioxide. The supercritical fluid maintained at an appropriate solubility parameter, swells the vulcanized rubber to a state of equilibrium swell. The cross links become fully extended and under strain to hold the internal pressures caused by the solvent swelling affect of the supercritical gas. When equilibrium swell has been achieved, the pressure within the processing vessel is rapidly dropped to a predetermined level causing a degassing and expansion of the supercritical fluid that has been absorbed within the vulcanized rubber. The resulting three dimensional separation of the rubber molecules will put a further rapid strain on the cross links, causing them to break, thereby giving the affect of de-vulcanization.

Abstract: The present invention relates to a method for preferentially breaking cross-links in a vulcanised rubber, thereby de-vulcanising the rubber, by the use of a supercritical fluid, such as carbon dioxide. The supercritical fluid maintained at an appropriate solubility parameter, swells the vulcanised rubber to a state of equilibrium swell. The cross links become fully extended and under strain to hold the internal pressures caused by the solvent swelling affect of the supercritical gas. When equilibrium swell has been achieved, the pressure within the processing vessel is rapidly dropped to a predetermined level causing a degassing and expansion of the supercritical fluid that has been absorbed within the vulcanised rubber. The resulting three dimensional separation of the rubber molecules will put a further rapid strain on the cross links, causing them to break, thereby giving the affect of de-vulcanisation.