Effect of filler auto-assembly on percolation transition in carbon nanotube/polymer composites

A series of composites with various content of multi-walled carbon nanotubes dispersed in polymer was tested for electrical properties. During isothermal annealing in the melt, dynamic percolation transition induced a tremendous increase in conductivity. The unstable structure also experienced a more than one order of magnitude reduction in percolation threshold. The insulator to conductor transition concurrently became softer, as revealed by a monotonous increase in the critical exponent, gradually departing from the universal value. These large and concomitant changes in percolation transition with annealing time were ascribed to the self-organization of the filler that favors the completion of the conductive network.