We present a three-dimensional simulation of electrical conductivity in isotropic, polydisperse rod networks from which we determine the percolation threshold (${\varphi }_c$). Existing analytical models that account for size dispersity are formulated in the slender-rod limit and are less accurate for predicting ${\varphi }_c$ in composites with rods of modest $L/D$. Using empirical approximations from our simulation data, we generalized the excluded volume percolation model to account for both finite $L/D$ and size dispersity, providing a solution for ${\varphi }_c$ of polydisperse rod networks that is quantitatively accurate across the entire $L/D$ range.

• Received 17 July 2012
• Corrected 3 January 2013

DOI:https://doi.org/10.1103/PhysRevB.86.214306