Thermodynamic Properties of Silicon Nitride and Boron Nitride/Natural Rubber Composites Co‐Modified by Tannic Acid and Silane Coupling Agent

ABSTRACT Using natural rubber as the polymer matrix, we systematically evaluate the impact of ternary filler systems (carbon black, boron nitride [BN], and silicon nitride [Si 3 N 4 ]) on composite properties. The filler is treated by a dual modification strategy combining non‐covalent modification of tannic acid (TA) and covalent modification of γ‐(2,3‐epoxypropoxy) propytrimethoxysilane (KH560). The influence of this modification method on the dispersion of fillers, the Payne effect, mechanical properties, thermal conductivity, and dynamic mechanical properties in the composite materials is mainly studied. The results show that the double modification optimizes filler dispersibility, enhances interfacial compatibility between the filler and rubber, and reduces interfacial thermal resistance. The BN‐Si 3 N 4 /NR composite demonstrates the best‐balanced comprehensive performance at a BN:Si 3 N 4 ratio of 13:7. Relative to N234/NR composites, the modified material exhibits a 17.2% enhancement in tensile strength accompanied by a 32.8% improvement in thermal conductivity; wear resistance increases by 40.3%, rolling resistance decreases by 19.7%, and anti‐wet slip performance is maintained. This research broadens the application potential of BN and Si 3 N 4 in rubber composites, providing new ideas for developing tire materials with high strength, high thermal conductivity, and low heat generation characteristics.