Computational micromechanics modeling of inherent piezoresistivity in carbon nanotube–polymer nanocomposites

It has been observed that carbon nanotubes have a measurable inherent piezoresistive effect, that is to say that changes in carbon nanotube strain can induce changes in carbon nanotube resistivity, which may lead to observable macroscale piezoresistive response of carbon nanotube–polymer nanocomposites. In this article, the focus is on modeling the effect of inherent piezoresistivity of carbon nanotubes on the nanocomposite’s piezoresistive behavior using computational micromechanics techniques based on finite element analysis. Both in-plane and axial piezoresistive responses are being considered in an electromechanically coupled code. The computational results are used to estimate the magnitude of the piezoresistive coefficients of carbon nanotube needed for the piezoresistive response of macroscale nanocomposites to be comparable with experimental data in the literature. It is found that the current values for inherent piezoresistivity of the carbon nanotube are not sufficiently large enough to explain the observed macroscale piezoresistive response if inherent piezoresistive effect of carbon nanotubes is the only driving force for the piezoresistive response of the macroscale nanocomposites, and hence, additional mechanisms such as electron hopping and nanotube–nanotube contact may play important roles either individually or in a coupled fashion with inherent piezoresistivity of the carbon nanotube.