Polyaniline/Ethylene Vinyl Acetate Composites as Dielectric Sensor

The compressive stress (pressure) sensitivity of dielectric properties has been studied on ethylene vinyl acetate (EVA)/polyaniline (Pani) composites prepared through In-situ synthesis of polyaniline in the solution of insulating EVA matrix. It is observed that the dielectric constant and loss increase with the increase in applied pressure, that is some piezoelectric effect is observed for these composites. The dielectric properties are also found to increase with respect to time when subjected under constant pressure. It is seen that changes in dielectric constant and loss follow some exponential relationships with respect to applied pressure and time duration under constant stress, and the relaxation time for the composites can be calculated. The relaxation time decreases with the increase in concentration of Pani in a composite. However, a composite with lower Pani content exhibits relatively higher change in dielectric properties against applied pressure and time duration under compression compared to one with higher loading. Granular crew type morphology of Pani is observed through scanning electron microscopic (SEM) study. This study reveals that these EVA-Pani composites can be used as dielectric sensor. (C) 2013 Society of Plastics Engineers