Improvement in dielectric properties of the three-phase GN–BaTiO3–PEK nanocomposites with and without silane coupling agent

Graphite nanoplatelets (GN)-barium titanate (BaTiO3)-polyetherketone (PEK) nanocomposites containing 3-aminopropyltriethoxy silane-treated and untreated BaTiO3 nanoparticles were successfully fabricated. A dielectric constant of ~ 13.9 was obtained for 50 wt%-treated BaTiO3–PEK nanocomposite. The nanocomposites showed a weak frequency-dependent dielectric constant with dissipation factor lower than 0.03. Fourier transform infrared spectroscopy confirmed the compatibility between the treated BaTiO3 nanoparticles and PEK. Interestingly, a similar value of dielectric constant was obtained for the nanocomposites containing 0.3 wt% GN and 30 wt% BaTiO3, thus decreasing the density of the materials without compromising dielectric properties. The nanocomposites exhibited thermal stability above 560 °C.