Effect of aging on electrical conductivity of two-dimensional composite with rod-like fillers

Two-dimensional composite with rod-like fillers has been simulated using a lattice approach. The fillers were assumed to be conductors, whilst the substrate (host matrix) was assumed to be an insulator. Rod-like fillers were considered as linear k-mers of two mutually perpendicular orientations (kx- and ky-mers) on a square lattice with periodic boundary conditions applied along both directions of the lattice. A random sequential adsorption was used to produce an initial homogeneous and isotropic distribution of fillers. By means of the Monte Carlo (MC) technique, translational diffusion of the fillers was simulated as a random walk, while rotational diffusion was ignored. At each given MC step, the system under consideration was transformed into a random resistor network (RRN); the Frank–Lobb algorithm was applied to calculate the electrical conductivity of such RRNs. Diffusional relaxation of the system leads to a kind of aging. For example, when concentration of fillers exceeds the percolation threshold, the aging leads to decreasing of the electrical conductivity and, in some cases, the inhibition of percolation was observed.