Percolation-based model for tunneling conductivity in systems of partially aligned cylinders

摘要

A model is developed for anisotropies in the conductivity in monodisperse systems of uniaxially aligned cylindrical fibers. Concepts from percolation theory (specifically, a lattice approach toward describing percolation by rods with large aspect ratios) are unified with a simple picture based upon resistors combined in series and parallel to calculate the conductivities in fiber-based nanocomposites in directions that are longitudinal and transverse with respect to the axis of particle alignment. Results obtained for three different orientational distribution functions (ODFs) reveal a peak in the dependence of the longitudinal conductivity upon mean orientational order parameter (), qualitatively similar to findings that have been reported from computer simulations. In contrast, the transverse conductivity decreases monotonically with increasing values of for each of the ODFs investigated.