Piezoresistive Natural Rubber Composites: A Comparison Between Low‐Temperature Glutaraldehyde Curing Agents and Conventional Sulfur Curing Systems

This study examines the piezoresistive behavior of natural rubber (NR) composites cured with sulfur (S) and glutaraldehyde (GA) and reinforced with a hybrid conductive system of conductive carbon black (CCB) and carbon nanotubes (CNT). GA‐cured NR composites demonstrated superior mechano‐electrical performance, achieving a tensile modulus of 2.05 MPa at 100% strain, tensile strength of 9.6 MPa, electrical conductivity of 10.2 μS/cm, and a gauge factor of 226 at 300%–500% strain. The improvement in modulus and piezoresistive response is attributed to the homogeneous distribution of crosslink points in the GA‐cured NR network. Notably, the secondary electrical signal peak observed in S‐cured NR sensors was eliminated with GA curing. Furthermore, GA‐cured composites exhibited reduced signal drift (dynamic cycling) and relaxation (quasi‐static cycling) compared to S‐cured composites. Long‐term soft tendon actuator tests confirmed the enhanced stability of GA‐cured systems. These findings indicate that GA‐cured NR composites with hybrid CCB/CNT fillers combine high stretchability, stability, and sensitivity, making them promising candidates for high‐performance piezoresistive sensors. Leveraging renewable NR, this approach supports sustainable development while enabling applications in wearable electronics, soft robotics, and health monitoring systems.