Eco‐Engineered ZnO /Ceramic Waste Nanocomposites as Dual‐Function Activators and Microwave Absorbers in Nitrile Rubber Vulcanization

In recent years, the growing concern over electromagnetic pollution has increased for effective control strategies to reduce excessive radiation effects on the human body. Consequently, microwave absorption materials have attracted considerable research interests. In this study, ZnO/ceramic waste nanocomposites (ZnO/CW) were synthesized by depositing ZnO nanoparticles onto nanosized ceramic waste with two ratios (e.g., 20% and 40%). The nanocomposites were completely characterized to confirm successful formation and structural integrity. ZnO/CW nanocomposites were incorporated into butadiene‐acrylonitrile rubber (NBR) formulations at loadings of 1–5 phr to evaluate their efficiency as activators and microwave absorbers. The impact of ZnO/CW nanocomposites on mechanical properties, curing behavior, and microwave absorption of NBR sheets was examined. The results proved that the ZnO/CW nanocomposites enhanced vulcanization efficiency, allowing reduced ZnO content, and showed uniform dispersion in the NBR matrix. Notably, the (40% ZnO/CW)/NBR sheets displayed a 94.8% increase in tensile strength and 21.6% in elongation at break compared to those containing commercial ZnO. The (40% ZnO/CW)/NBR sheets exhibited outstanding microwave absorption (> 90% in the 8–12 GHz range), arising from optimized impedance matching and strong attenuation as evidenced by S‐parameter analysis. Cole–Cole plots revealed multiple overlapping dielectric relaxation processes, which underpin the observed broadband absorption behavior. Consequently, (ZnO/CW)/NBR sheets represent lightweight, flexible, and cost‐effective microwave absorbers that enable ZnO reduction and support sustainable rubber manufacture.