Effects of curvature and alignment of carbon nanotubes on the electrical conductivity of carbon nanotube-reinforced polymers investigated by mesoscopic simulations

Carbon nanotube-reinforced polymers belong to a class of composite materials, which have been largely investigated due to their special electrical, thermal and mechanical properties. In the case of electrical conductivity of carbon nanotube-reinforced polymer, a critical amount of carbon nanotubes as a filler material enables a sharp increase of electrical conductivity. At this certain volume fraction of carbon nanotubes, the material turns into a conductor because of the percolation effect. This effect occurs due to the formation of a closed pathway of filler material through the system. Mesoscopic simulation models of these materials were carried out to predict their electrical conductivity. In this paper, the effects of carbon nanotube curvature and their alignment parallel or perpendicular to the electrical flow direction inside a representative volume element were analysed and an optimized carbon nanotube distribution is presented. A network with a longest average path length per (rigid) carbon nanotube but also cross-linking (only nearly isotropic alignment) shows the best conductivity in the preferred direction.