Designing of cradle-to-cradle loops for elastomer products

Reuse of devulcanisates in virgin rubber compounds is the shortest loop in cradle-to-cradle cycles for elastomers. Due to the enormous complexity of these loops, the technology still stands in its infancy. Two elastomer types, EPDM (Ethylene–Propylene-Diene Terpolymer) and SBR (Styrene–Butadiene Rubber), are compared as to their ease of devulcanisation with an optimized devulcanisation aid. EPDM is relatively easy to devulcanise into a quality which allows for reuse of large amounts till 50% in virgin compounds for applications like roofing sheets and others. This is already being done on industrial scale. SBR is more difficult to devulcanise due to re-crosslinking under the influence of oxygen. Furthermore, tyre scrap is a mix of compounds and elastomers, which are impossible to segregate before devulcanisation. A lot more research and development is needed to bring this to a success.