"The general problem of reclaiming of rubber is the fact that besides crosslinks also polymer chains are broken in this process, and this influences the properties and reduces the quality of the recycled material. An efficient devulcanization is needed in order to achieve a highquality recycled rubber. Within this study, the breakdown of sulfur-cured SBR (Styrene Butadiene Rubber) in a thermal de-vulcanization process is investigated under various conditions: The temperature range for the de-vulcanization is varied from 180 °C to 300 °C, and the treatments are done in air and in nitrogen under oxygen exclusion. Depending on the parameters used, the sol fraction increased as expected, crosslink density first decreased, but increased again above a temperature threshold of 220 °C. The reason for this increase in crosslink density is a complicated intramolecular rearrangement of chain fragments due to uncontrolled degradation and oxidation effects. Preventing oxidation during thermal treatment reduces the degree of rearrangement and results in significantly improved SBR devulcanizate properties."