A solvent dispersion method for the preparation of silicone composites filled with carbon nanotubes

Abstract

This work deals with preparation of CNT based silicone composites with a view to control the value of percolation threshold. To this end, the effect of organic solvent N-methyl-2-pyrrolidone (NMP) on dispersion of CNT in silicone (resulting in electrically conductive composites) was studied. Nanocomposites preparation comprised several steps: (1) dispersing CNTs in aqueous solution of NMP; (2) mixing them into a low viscosity silicone matrix using sonication; (3) curing of homogeneously distributed CNTbased composition by curing agent. As a result, three types of composites differing in preparation method and with different CNT content (0-7 vol.%) were prepared. DC and AC conductivities as well as dielectric properties of nanocomposites were studied. The results obtained show that modification of CNT caused the increase of percolation threshold from 2 (for unmodified CNT) to 4 vol.%. Such a shift can be explained by the insulation/ separation of individual CNTs. The separation of CNTs decreases the probability of percolation cluster formation, but increases the area of CNT-polymer matrix interface leading to the decrease of charge transport.