Electrical Percolation in Multicomponent Composites: Monte Carlo Simulation and Experiment*

A three-dimensional continuum percolation model has been developed based on Monte Carlo simulation to investigate the percolation behavior of an electrically insulating matrix reinforced with multiple conductive fillers of different dimensionalities. The model is able to predict the electrical percolation threshold in such multicomponent composites. The main finding is that a combination of multiple fillers with different dimensionalities can achieve a reduced working concentration below the percolation threshold of each single component, which has been confirmed by experimental results. Furthermore, impenetrable fillers of large aspect ratio preferentially align with each other to maximize the packing entropy rather than forming percolating cluster of randomly oriented fillers, and this entropy-driven transition from isotropic to nematic phase is found to affect the percolation threshold besides the concentrations of fillers. It suggests that the overall alignment of fillers characterized by a smaller nematic order parameter leads to a lower percolation threshold.