Sensitivity and dynamic electrical response of CNT-reinforced nanocomposites

A series of dynamic compressive experiments were performed to experimentally investigate the electrical response of multi-wall carbon nanotube (CNT)-reinforced epoxy nanocomposites subjected to split Hopkinson pressure bar (SHPB) loading. Low-resistance CNT/epoxy specimens were fabricated using a combination of shear mixing and ultrasonication. Utilizing the CNT network within, the electrical resistance of the nanocomposite was monitored using a high-resolution four-point probe method during each compressive loading event. In addition, real-time deformation images were captured using high-speed photography. The percent change in resistance was correlated to both strain and real-time damage. The results were then compared to previous work conducted by the authors (quasi-static and drop weight impact) in order to elucidate the strain rate sensitivity on the electrical behavior of the material. Furthermore, the percent change in conductivity was determined using a Taylor expansion model to investigate the electrical response based on both dimensional change as well as resistivity change during mechanical loading within the elastic regime. Experimental findings indicate that the electrical resistance is a function of both the strain and deformation mechanisms induced by the loading. The bulk electrical resistance of the nanocomposites exhibited an overall decrease of 40–65% and 115–120% during quasi-static/drop weight and SHPB experiments, respectively.