Comparative Evaluation of Recovered Carbon Blacks From Tire and Plastic Wastes in <scp>EPDM</scp> Formulations for Automotive Sealing Applications

ABSTRACT Ethylene–propylene–diene (EPDM) rubber compounds are widely employed with carbon black (CB) as the primary reinforcing filler. However, the environmental burden associated with conventional furnace carbon black has encouraged the search for more sustainable alternatives. Recovered carbon black (rCB), produced through the pyrolysis of polymeric wastes, represents a potential substitute, although its physicochemical characteristics are strongly influenced by the feedstock origin—a relationship that remains insufficiently understood in the context of automotive sealing applications. In this work, rCBs derived from two different waste streams—end‐of‐life tires (ELT) and plastic waste (PW)—were comparatively investigated as partial replacements (0%–40%) for commercial CB in EPDM formulations developed. The compounds were evaluated in terms of rheological behavior, curing characteristics, dynamic viscoelastic response, mechanical performance, thermal stability, and morphology. This work clarifies how feedstock origin governs filler characteristics and reinforcement efficiency related to compound performance. Results highlight distinct physicochemical profiles: ELT‐rCB provides higher surface activity (IAN: 113 vs. 37 mg I 2 /g) and moderate ash content (~20%), delivering reinforcement efficiency and cure behavior closer to commercial CB; PW‐rCB exhibits lower aggregate structure (OAN: 58 vs. 97 mL/100 g) and higher inorganic residue (~38%), acting as a less reinforcing filler and producing noticeable changes in viscoelastic response. Both rCB types provide satisfactory mechanical properties, processing behavior, and curing performance at replacement levels up to 20%, beyond which performance trade‐offs become significant. Overall, these findings demonstrate the feedstock‐specific performance profiles and practical incorporation limits, providing actionable guidelines for selecting rCB sources in sustainable EPDM based compound design according to targeted requirements.