Investigation of filler network percolation in carbon black (CB) filled hydrogenated butadiene-acrylonitrile rubber (HNBR)

Abstract

The filler network is one of the most important concepts in filled rubber nanocomposites. It ensures the rubber matrix some properties, such as electrical conductivity, heat conductivity, reinforcement property, and so on. The more or the less the filler content, the worse the combination properties. Therefore, the filler network percolation threshold is very significant to be controlled. In this work, the filler network percolation in CB filled HNBR was investigated, combining dielectric with dynamic and quasi-static mechanical measurement. The results showed there are two sudden increases in the platform value of the conductivity by 1–3 orders of magnitude by means of dielectric measurement. They are defined as the (α) process and the (α′) process, respectively. The (α) process that the CB content is between 25 vol.% and 26.5 vol.% is classified to the electric percolation threshold, according to the percolation theory prediction. Meanwhile, the (α′) process that the CB content is between 21.7 vol.% and 23.4 vol.% corresponds to the mechanical percolation threshold, according to the result of mechanical measurement.