Dynamic percolation of carbon nanotubes in liquid medium

Abstract

In this article we have measured the electrical behaviour of carbon nanotubes (CNTs) suspended in electrically insulating liquid. The concentration dependence of conductivity shows a percolation behaviour similar to that observed in electrical composites with an insulating matrix. The value of the critical percolation concentration is strongly determined by the aspect ratio of the fillers forming the network through dynamic percolation. We characterized several single- and multi-wall carbon nanotube materials by the newly proposed method and received a good correlation with the results obtained by methods commonly used for CNT characterization (Raman spectroscopy, transmission electron microscopy and electrical conductivity of free standing papers). As a comparison, fine graphite material has also been evaluated. The electrical properties of the suspensions can be used as a method for CNT characterization. This method can yield important information for CNT producers and for the selection of electrically conducting structures for composites applications.