Enhancing Mechanical and Antibacterial Performance of Tire Waste/Epoxidized Natural Rubber Blends Using Modified Zinc...

This study investigates the synergistic effects of incorporating modified zinc oxide-silica (ZnO-SiO₂) into tire waste (TW) and epoxidized natural rubber (ENR) blends, with a focus on crosslinking dynamics, mechanical reinforcement, and antibacterial activity. The addition of ZnO-SiO₂ significantly enhanced crosslink density, as evidenced by increased torque and accelerated cure rates. An optimal concentration of 10 phr was found to yield the highest performance. This optimal balance between chemical activation and mechanical reinforcement resulted in exceptional tensile properties, including notable improvements in Young's modulus, tensile strength, and strain-induced crystallization (SIC). These enhancements were attributed to the strong interactions between ENR molecular chains and SiO₂ surfaces. However, excessive ZnO-SiO₂ concentrations caused filler agglomeration, which reduced both mechanical and antibacterial performances. An antibacterial analysis revealed a remarkable 99.9% bacterial reduction at 10 phr ZnO-SiO₂, attributed to the Zn²⁺ ion release and reactive oxygen species (ROS) generation, with sustained activity even after thermal aging. This durability underscores the composites' potential for long-term applications. The findings establish ZnO-SiO₂ as a dual-functional filler that optimizes crosslinking, enhances mechanical properties, and provides durable antibacterial efficiency. These results highlight the potential of TW/ENR blends while offering critical insights into mitigating filler agglomeration to improve overall material performance.