A solvent dispersion method for the preparation of silicone composites filled with carbon nanotubes
aCentre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Nad Ovčírnou 3685, 760 01 Zlín, bPolymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T. G. Masaryka 275, 762 72 Zlin
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.
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