Development of Conductive Network of Multiwalled Carbon Nanotubes in Polycarbonate Melt

The effect of applied thermal history on the rheological properties in a molten state and the electric properties in a solid state is evaluated using mechanically blended samples composed of polycarbonate and multiwalled carbon nanotubes (MWNTs). It is found that MWNTs orient perpendicular to the applied compression direction owing to the squeeze flow at compression molding, which is prominent for the sample compressed at low temperature. The orientation of MWNTs reduces the interparticle contacts between MWNTs and thus decreases the electrical conductivity. Postprocessing annealing procedure at high temperature, however, leads to random orientation due to Brownian motion and then improves the electrical conductivity. The transition from an electrical insulator to a conductor by the redistribution process, which is called dynamic percolation, is well detected by the rheological measurements. POLYM. COMPOS., 32:97-102, 2011. (C) 2010 Society of Plastics Engineers