Evaluation of Electrical and Piezoresistive Properties of Carbon Black/Polyurethane Nanocomposite for Strain Sensing Applications

Nanocomposite sensors are gaining importance due to their cost-effectiveness and the ability to modify their properties for various applications. This study investigates the electrical and piezoresistive properties of polyurethane (PU)/carbon black (CB) nanocomposites for strain-sensing applications. Nanocomposite films were prepared by mixing varying weight percentages of CB (3-6 wt %) using a direct method, followed by sonication and screen printing. The characterization of carbon black (CB) particles and nanocomposite microstructure were examined using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), while their thermal stability and degradation behavior were assessed by Thermo-Gravimetric Analysis (TGA) under different temperature conditions. The strain-sensing performance was evaluated using a four-point probe system under tensile strain. The samples with 3 wt% carbon black showed the highest sensitivity, with a gauge factor of 51.64 at 20% strain, due to an optimal conductive network. The gauge factor decreases as the carbon black percentage increases for all strain levels. The results indicate that the piezoresistive behavior and strain-sensing performance of the nanocomposite significantly depend on the concentration and dispersion of carbon black (CB) particles. These findings suggest that PU/CB nanocomposites hold potential for flexible, wearable strain sensors with high sensitivity, making them suitable for structural health monitoring applications.