Dielectric properties of thermoplastic elastomer/zinc oxide (ZnO) nanocomposites with controlled nanoparticles dispersion

In this study, the rheological and dielectric properties of two sets of nanocomposites prepared respectively from Styrene-Ethylene-Butylene-Styrene (SEBS) and SEBS grafted maleic anhydride (SEBS-g-MA) block copolymer matrices and surface functionalized zinc oxide nanoparticles have been investigated. The interaction at the polymer-nanoparticle interface was tuned through the MA graft in order to tailor the nanoparticles dispersion in the block copolymer nanostructure and to highlight its effect on the dielectric performance. Small Amplitude Oscillatory Shear (SAOS) measurements revealed highly improved solid-like behavior and a low frequency independent storage modulus in SEBS-g-MA based nanocomposite which indicates good dispersion and formation of a network between the nanoparticles and the polymer chains. This result was supported by a reduction in the adsorbed carbonyl peak in Fourier Transformed Infrared (FTIR) spectra attributed to an interaction between MA graft and the functional groups on the surface of ZnO nanoparticles. The dielectric spectroscopy revealed a limited increase of both real and imaginary parts of the dielectric permittivity and absence of interfacial relaxation peak, in the case of SEBS-MAZnO nanocomposite. Besides, the AC short term breakdown strength was slightly improved in the SEBS-MA-ZnO nanocomposite compared to the pure matrix while it decreased by 18% in SEBS-ZnO nanocomposite due to the presence of agglomerations.