Dielectric and piezoelectric properties of polyetherimide/BaTiO3 nanocomposites

Polyetherimide/barium titanate (PEI/BaTiO3) nanocomposite films were prepared by mixing the fine BaTiO3 particles into poly(amic acid) solution under ultrasonication, followed by film casting and thermal imidisation. The nanocomposite structure and properties were characterised by FT-IR, XRD and SEM and the dielectric properties including frequency, ceramic concentration and temperature were analysed. In comparison with pure polyetherimide, the dielectric constant of the nanocomposite (50 vol% BaTiO3) was significantly improved by twelve times while the loss tangent increased only five times. The nanocomposites showed good dielectric stability over a wide range of temperature and frequency. Different theoretical approaches have been used to predict the effective dielectric constant of the nanocomposite systems and the estimated results were compared with the experimental data.