Improvement of the electrical conductivity in multiphase epoxy-based MWCNT nanocomposites by means of an optimized clay content

The improvement of the DC conductivity of nanocomposite based on an epoxy matrix filled with multi wall carbon nanotubes (MWs) by using an optimized Hydrotalcite clay (HT) content is discussed. Multiphase nanocomposites with fillers content less than 1 wt% are considered in order to exploit the dispersion mechanism introduced by the clay. A Design of Experiment (DoE) procedure with a coarse parameter space sampling is adopted in order to explore and optimize the electrical properties of the nanocomposite without altering sensibly the mechanical ones. The implemented technique puts in evidence a non-linear dependence of the composite electrical conductivity from the clay content. Furthermore an optimized 0.6 wt% of HT with 1 wt% MW multiphase composite is found leading to the higher electrical conductivity in the considered parameters space. The optimized design and the non-linear effect are experimentally validated. Some possible mechanisms responsible for the obtained results are discussed.