Dynamic mechanical and dielectric relaxation studies of chlorobutyl elastomer nanocomposites

Abstract

Primary and secondary relaxation behavior of chlorobutyl elastomer nanocomposites have been studied as a function of variation in nanographite loading in the temperature range from −100°C to +100°C and in the frequency range of 100–106 Hz respectively. The effect of nanographite loadings on glass transition temperature was marginal for all the composites in the narrow range of −10°C to 10°C. The nonlinearity in tan δ and storage modulus has been explained on the concept of filler–polymer interaction and aggregation of nanographites. The effect of variation in nanographite loadings on the dielectric relaxation such as complex and real parts of impedance was distinctly visible. The electric modulus formalism has been utilized to further investigate the conductivity and relaxation phenomenon. The frequency dependence of electrical conductivity has been investigated using percolation theory. The phenomenon of percolation in the composites has been discussed based on the measured changes in electrical conductivity. The percolation threshold as studied by electrical conductivity occurred in the vicinity of 4–6 phr of nanographite loading. Cole–Cole, Nyquist plots, and Argand diagram confirm the existence of non-Debye/nonlinear relationship. Scanning electron microscopic images show agglomeration of the nanographite and formation of a continuous network structure.