Anomalous electrical conductivity and percolation in carbon nanotube composites

Anomalous electrical behavior in carbon nanotube (CNT)-reinforced composites and suspensions with ultra-low loading of fillers has been examined by means of percolation theory. A simple model, based on the concept of renormalization, has also been proposed to estimate the electrical percolation threshold of CNTs in composites. CNT-reinforced composite exhibit an electrical percolation with addition of 0.1 vol.% or less fillers, at which electrical conductivity increases sharply and significantly. It has been established that the percolation threshold of CNTs is closely dependent on their geometric factor such ad volume fraction, size, and orientation, and the interaction between them. The percolation threshold of CNTs has been observed to be inversely proportional to their aspect ratios. Percolation threshold of expensive CNTs can be decreased by using long CNTs or by increasing the strength of interaction between them.