In this work, an extrusion process has been developed for the devulcanization of rubber crumb from recycled tires employing supercritical CO2. For that purpose supercritical CO2 has been injected in a twin screw extruder to swell the rubber crumb and to facilitate the otherwise impossible rubber extrusion process. As a consequence, waste rubber can be processed under mechanical shear and extensional forces at various operating conditions that may lead to different degrees of devulcanization. The feeding flow rate of rubber powder to the extruder was found to affect the extent of devulcanization, and have an impact on the product viscosity and processability. Although CO2 concentration was a very important factor for the flow ability and extrusion, it was found to have little influence on the degree of devulcanization. In addition, the type of screw configuration employed affected significantly the rheological properties of the devulcanized rubber due to the varying amount of deformation that it imparts on the rubber crumb. Finally, the screw speed and the processing temperature also affected the viscosity behavior of the devulcanized rubber powder. Soxhlet extraction was used to evaluate the degree of devulcanization under various conditions and FTIR analysis indicated that significant changes occurred on the chemical structure of recycled rubber crumb due to the formation of new double bonds and scission of carbon-carbon bonds and carbon-sulfur bonds.
Devulcanization of recycled tire rubber using supercritical carbon dioxide
Entvulkanisierung von wiederaufbereitetem Fahrzeugreifengummi mit Hilfe von überkritischem Kohlendioxid
2004
5 Seiten, 5 Bilder, 14 Quellen
Conference paper
English
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