Mechanochemical devulcanization of <scp>EPDM</scp> rubber waste. Correlation of process parameters with sol–gel analyses and revulcanization properties

Ethylene–propylene–diene rubber (EPDM) scrap was devulcanized in an internal mixer with varying amounts of dibenzamido diphenyl disulfide (DBD) at temperatures below 200°C. The devulcanization effect and sol–gel analyses the devulcanizates, mechanical properties sulfur-cured revulcanizates were studied. Residual DBD still present sol 160°C degraded affects curing leading to poor properties. So, temperature must be adjusted according concentration obtain a superior recyclate for sealing systems. At 0.4 wt% DBD, degradation reaction already complete 120°C, but only 52% 61% tensile strength σ strain break ε virgin material achieved. 2 wt%, complete, on small; 65% 86% recovered, respectively. To prevent property degradation, 200°C required 3.9 resulting 97% 95% ε, 70% hardness.