Comprehensive numerical characterization of the piezoresistivity of carbon nanotube polymer nanocomposites

Polymer nanocomposites reinforced with carbon nanotubes (CNTs) are promising materials for applications in flexible sensors and self-sensing structures due to their enhanced mechanical and electrical properties. This study investigates the piezoresistive behavior of CNT/polymer nanocomposites to establish structure-property relationships addressing the limitations in modeling of the piezoresistivity under varying mechanical strains. Monte Carlo simulations were employed to account for uncertainties in the microstructure of the nanocomposite by randomly dispersing CNTs within the representative volume element. The fiber reorientation model was used to simulate the mechanical deformation effects on CNT kinematics, while the Landauer-B & uuml;ttiker formula was used to calculate the tunneling resistance between CNTs. The developed model was validated against experimental data to ensure its reliability. The study systematically analyzed the impact of key parameters, including CNT aspect ratio, polymer energy barrier height, Poisson's ratio, CNT volume fraction, intrinsic CNT conductivity, and the number of CNT conduction channels, on the piezoresistive sensitivity under both tension and compression. One key finding is the contrasting effect of parameters like polymer energy barrier height and CNT intrinsic conductivity under tensile versus compression loadings. Piezoresistivity increases with higher values of energy barrier heights and CNT conductivity under tensile strain but decreases under compression. This comprehensive characterization enhances the design and optimization of CNT/polymer nanocomposites guiding future developments in smart materials and sensing technologies.