Enhancing mechanical and physical properties of natural rubber nanocomposites with classical and nanofillers: experimental and numerical modeling approach

This study investigated the effects of varying contents of carbon black, Iraqi kaolin, and graphene nanofillers on the cure characteristics, mechanical properties, abrasion resistance, tear behavior, and fatigue performance of the natural rubber (NR) composites. It was found that the addition of nanofillers to the rubber matrix improved the tensile strength, fracture strain, tensile modulus, and fatigue behavior. In comparison with virgin NR, the addition of carbon black (CB) at 30, 45, 60, and 75 phr, as well as equivalent amounts of Iraqi kaolin filler with similar compound formulations, resulted in varying tensile strength. The maximum tensile strength observed was 16.73 MPa for 75 phr CB, 7.917 MPa for 45 phr Iraqi kaolin, and 8.633 MPa for graphene. Furthermore, the hardness of NR reinforced by CB, graphene, and Iraqi kaolin fillers was obtained as 70 for 75 phr CB, 38 for 2 phr graphene, and 33 for 75 phr Iraqi Kaolin, respectively. It was found that hardness increases steadily with CB loading, up to + 126% at 60 phr, while elongation at break decreases consistently, up to − 39%. Modulus also shows a significant increase, highest of + 611% at 60 phr. In comparison, tensile strength not only improves significantly but also shows the highest gain (+ 120%) at 60 phr. Among the models evaluated, the neo-Hookean model provides a simple and efficient fit for experimental data up to 30% strain, requiring minimal computational effort. For moderate strain levels, models such as Mooney-Rivlin and reduced polynomial formulations are suitable, accurately accommodating strains up to 100%. Better dispersion of graphene improves the composite’s mechanical strength and functional performance, making it useful in high-performance seals, vibration-damping components, and flexible electronic devices.