Universal resistivity–strain dependence of carbon nanotube/polymer composites

The resistivity response upon stretching of a carbon nanotube/thermoplastic elastomer composite fabricated by a solution process with good nanotube dispersion and low percolation threshold $({p}_{c}\ensuremath{\sim}0.35\phantom{\rule{0.3em}{0ex}}\mathrm{wt}\phantom{\rule{0.2em}{0ex}}%)$ is reported. The relationship between resistivity and strain (deformation) shows an exponential relationship with universal, nanotube concentration-independent behavior. The temperature dependence of the resistivity is described by the fluctuation induced tunneling model. The experimental resistivity-strain dependence greater than 5% strain is interpreted in terms of this model by consideration of the gap-width modulation of tunnel junctions. Percolation theory applied to the conductive nanotube network indicates that for less than 5% strain, deformation of the conductive network is the controlling mechanism for changes in resistivity.