Eco-Functional Epoxy Composites from Recycled ZnO and Tire Rubber: A Study on Breakdown Voltage Enhancement

The increasing demand for sustainable materials in electrical engineering has encouraged the substitution of conventional fillers in epoxy insulation with recycled industrial by-products. This study investigates the potential use of waste tire rubber particles and zinc oxide recovered from electric arc furnace dust as eco-friendly fillers for epoxy resins in high-voltage insulation applications. Four material variants were fabricated: pure epoxy, epoxy with 10 wt% ZnO (0.7 mm thickness), epoxy with 10 wt% tire rubber (0.9 mm thickness), and epoxy with 20 wt% tire rubber (0.9 mm thickness). The breakdown voltage of each composite was measured under AC voltage. Results indicate that filler type and concentration influence breakdown behavior within each thickness group. The 10 wt% ZnO-filled epoxy exhibited a moderate enhancement in breakdown voltage compared with pure epoxy of the same thickness, consistent with interfacial modifications commonly observed in oxide-filled epoxy systems. Conversely, tire rubber fillers led to reduced breakdown performance, likely due to increased dielectric heterogeneity introduced by the elastomeric phase. No direct comparison between ZnO- and rubber-filled systems was performed due to differences in manufacturable sample thickness. The findings contribute to the evaluation of recycled fillers in dielectric composite systems within a circular-economy framework.