Enhanced Mechanical and Thermal Properties of Carbon Black–Reinforced Epoxidized Natural Rubber via Zinc Chloride Coordination Crosslinking

ABSTRACT This study investigates the enhanced properties of epoxidized natural rubber (ENR‐50) crosslinked through zinc chloride (ZnCl 2 ) coordination and reinforced with varying carbon black (CB) loadings. Comprehensive analyses, including Fourier transform infrared spectroscopy (FT‐IR), curing characteristics, mechanical testing, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM), were conducted to assess the effects of CB on the properties of ENR‐ZnCl 2 composites. The results confirm that CB reinforcement significantly improves tensile strength (from 1.18 MPa to 4.68 MPa), 100% modulus (from 0.66 MPa to 3.58 MPa), and hardness (from 39.60 to 71.47 Shore A), although it has an inverse effect on elongation at break. Additionally, CB influences the vulcanization process by partially adsorbing ZnCl 2 , which delays the crosslinking reaction, thereby extending cure times from 9.34 min (ENR‐ZnCl 2 ) to 37.90 min at a CB loading of 50 phr. Increasing CB content further enhances the delta torque, initial storage modulus, crosslink density, bound rubber content, Payne effect, and decomposition temperature, especially under oxidative conditions. This study provides insights into optimizing ENR composites for high‐performance applications, emphasizing the synergistic effects of ZnCl 2 coordination crosslinking and CB reinforcement at different loadings.