Electrical and mechanical properties of aluminum-loaded NBR composites

Abstract

The present work aims at studying the effect of adding aluminum (Al) powder at different concentrations as white fillers on the electrical and mechanical properties of the acrylonitrile butadiene rubber (NBR) vulcanizates. Tensile strength and elongation at break decreased by the addition of Al up to 150 phr; the experimental stress–strain results showed a good fitting with the general form proposed by Menges and Schmachtenberg ( Kunststoffe 1983; 73: 543–546; Kunststoffe 1987; 77: 289–292), Michaeli et al. ( Kunststoffe 1989; 79: 692–700). For most of the NBR composites, the Poole–Frenkel conduction mechanism was dominant at room temperature. The dielectric characteristics revealed a percolation threshold at 50 phr. Using Tsangaris et al. ( Mater Sci Tech 1996; 12(7): 533) model for all Al volume fractions of Al/NBR composites resulted in a good agreement between the calculated and the experimental values of the dielectric constant. Finally, a simple equivalent circuit model was successfully used to describe frequency dependence of both the dielectric constant and the AC electrical conductivity of Al/NBR composites.