Dielectric relaxation behavior of conducting carbon black reinforced ethylene acrylic elastomer vulcanizates
Abstract
The dielectric relaxation characteristics of conductive carbon black (CCB) reinforced ethylene acrylic elastomer (AEM) vulcanizates have been studied as a function of frequency (101–106 Hz) at different filler loading over a wide range of temperatures (30–120°C). The effect of filler loadings on the dielectric permittivity (ε′), loss tangent (tan δ), complex impedance (Z*), and electrical conductivity (σac) were studied. The variation of ε′ with filler loading has been explained based on the interfacial polarization of the fillers within a heterogeneous system. The effect of filler loading on the imaginary (Z″) and real (Z′) part of Z* were distinctly visible, which may be due to the relaxation dynamics of polymer chains at the polymer–filler interface. The frequency dependency of σac has been investigated using percolation theory. The phenomenon of percolation in the composites has been discussed in terms of σac. The percolation threshold (ϕcrit) occurred in the range of 20–30 phr (parts per hundred) of filler loading. The effect of temperature on tan δ, ε′, σac, and Nyquist plots of CCB-based AEM vulcanizates has been investigated. The CCB was uniformly dispersed within the AEM matrix as studied from the transmission electron microscope (TEM) photomicrographs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
