Interface Polarization Effect on Dielectric and Electrical Properties of Polyurethane (PU)/Polyaniline (PANI) Polymer Composites

In this study conductive polymer composites of polyurethane (PU)/polyaniline (PANI) below the percolation threshold were prepared by using solution casting. The dispersion of the conductive PANI fillers within the PU matrix was investigated by scanning electron microscopy (SEM). The SEM results showed a relatively homogeneous dispersion of the PANI fillers within the polymeric matrix. The effects of filler concentration on the dielectric and electrical conductivity depend upon the interface between conductive filler and matrix. Dielectric properties and ac conductivity of polymer composites have been investigated at different frequencies (10 2 - 10 5 Hz). The results show that the dielectric constant, dielectric loss and the electrical conductivity are strongly dependent on the frequency. The dielectric constant and dielectric loss decreased, whereas electrical conductivity increased with increasing frequency. In addition, the dielectric constant and conductivity increase when concentration of PANI increased. Differential scanning calorimetry (DSC) presented an enhanced the glass transition temperature (Tg) of the polymer composite with increasing PANI fillers. A correlation of Tg and the interface polarization between the PANI fillers and PU matrix on dielectric properties was proposed.