Electrical conductivities of composites with aligned carbon nanotubes

This paper reports an analysis of the effect of nanotube alignment on the electrical conductivity of carbon nanotube-based composites using a percolation model. Both straight and wavy nanotubes are considered. The thickness of an insulating matrix film between crossing nanotubes is randomly selected in the range of 0-1.8 nm and the resulting contact resistance is correspondingly determined based on the Simmon's formula. Results of Monte Carlo simulations indicate that the electrical conductivity of composites with aligned nanotubes is either lower or higher than that of composites with random nanotube orientation, depending on the degree of alignment and for wavy nanotubes the highest conductivity occurs when nanotube are slightly aligned. The anisotropy of conductivity is also found strongly affected by nanotube alignment especially when the nanotube contents are small. The findings reached in this study coincide with some experimental observations on carbon nanotube-based composites.