Structural Health Monitoring of Nanocomposite Bonded Energetic Materials Through Piezoresistive Response

The application of in situ structural health monitoring in polymer bonded explosive materials through the introduction of carbon nanotubes into the binder phase is investigated through piezoresistive response under quasi-static loading, to provide the basis for deformation and damage sensing for real-time self-diagnostic functionalities in energetic materials. The experimental effort herein is focused on inert energetics using 70 wt % ammonium perchlorate and mock energetics using 70 wt % sugar crystals embedded into epoxy binder, having concentrations of 0.1 and 0.5 wt % multiwalled carbon nanotubes relative to the entire hybrids. Electrical conductivity, dielectric properties, mechanical properties, and piezoresistive sensitivities of inert and mock energetics are quantitatively and qualitatively evaluated. Electrical conductivity and dielectric constant were improved ∼3 and ∼5, and ∼1 and ∼2, orders of magnitude for 0.1 and 0.5 wt % multiwalled carbon nanotube inert hybrid energetics and mock hybrid energetics from that of the baseline neat inert energetics and neat mock energetics, respectively. Incorporating multiwalled carbon nanotubes into local binder improved tensile modulus of ammonium perchlorate inert hybrid energetics and sugar mock hybrid energetics, ∼15 and ∼70%, respectively, and tensile strength of sugar mock hybrid energetics ∼40% compared with neat inert energetics and neat mock energetics. Significant piezoresistive response was obtained both for multiwalled carbon nanotube ammonium perchlorate inert hybrid energetics and multiwalled carbon nanotube sugar mock hybrid energetics, demonstrating the electromechanical characterization of inert and mock energetic materials, which provides proof of concept for strain and damage sensing under quasi-static loading for real-time structural health monitoring in energetics.