High Strain Rate Behavior and Energy Absorption of Nano-Silica Reinforced NR/NBR Blends: Temperature-Dependent SHPB Investigation

This study investigates the dynamic compressive behavior of natural rubber (NR)/acrylonitrile butadiene rubber (NBR) blends containing 20 phr carbon black and reinforced with 3 phr nano-silica under high strain-rate loading using a Split Hopkinson Pressure Bar (SHPB). The effects of temperature (−50 °C, 25 °C, and 100 °C) and blend composition on viscoelastic properties, densification, and energy absorption were evaluated. Dynamic mechanical analysis (DMA) showed that nano-silica increased the storage modulus (E′) and reduced the tan δ peak, indicating enhanced stiffness and stronger filler–matrix interactions. SHPB tests revealed a pronounced temperature dependence, with elastoplastic behavior at −50 °C and softening at 100 °C due to increased molecular mobility. The stress–strain response exhibited three characteristic stages: linear elasticity, plateau, and densification, with the highest densification strain observed at room temperature. Nano-silica significantly improved energy absorption at 10% and 30% strain, whereas unfilled blends showed greater damping with increasing NBR content at low temperatures. These findings demonstrate the combined influence of nano-silica, temperature, and blend composition on the impact resistance of NR/NBR composites.