Improving the thermal and electrical properties of polymer composites by ordered distribution of carbon micro- and nanofillers

This article presents the study of electrical and thermal properties of segregated polymer composites based on ultra-high-molecular-weight polyethylene (UHMWPE) filled with carbon fillers (nanofiller graphene (Gr), microfiller anthracite (A) and hybrid filler Gr/A). It is shown that the formation of a segregated structure with an ordered distribution of the filler leads to a high local concentration in the intergrain boundaries, which causes a lower percolation threshold. Thus, in the composite UHMWPE + A, the percolation threshold is an order of magnitude lower than for a system with a random distribution of the filler. The segregated composite with nanofiller UHMWPE + Gr provides a 14-fold lower percolation threshold than the composite with microfiller UHMWPE + A. Composite with the hybrid filler Gr/A also exhibits a low percolation threshold close to the UHMWPE + Gr. The plot of the thermal conductivity versus filler content does not show the percolation behavior and obeys the equation of the Lichtenecker. The thermal conductivity parameter lambda(f) in the segregated system is 4.4 times higher than for the uniform distribution of the filler that indicates an increased thermal transport through the filler phase located at the boundaries in the segregated structure. (C) 2019 Published by Elsevier Ltd.