Frequency and temperature dependent dielectric properties of polyvinyl alcohol/polystyrene sulfonic acid/cobalt oxide nanocomposite films

Abstract

ABSTRACT Polyvinyl alcohol (PVA), polystyrene sulfonic acid (PSSA), and cobalt oxide (Co3O4) nanoparticles are used in the ease and low-cost solution casting method to prepare flexible nanocomposite films. Structural and morphological studies were carried out for the nanocomposites. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies revealed an excellent interaction between the host polymer and Co3O4 nanoparticles. Scanning electron microscopy (SEM) was employed to study the surface morphology of the PVA/PSSA/Co3O4 nanocomposite films, which exhibited homogeneous dispersion of nanoparticles within the host matrix. Stress–strain curves were obtained to evaluate the mechanical properties of PVA/PSSA/Co3O4 nanocomposite films. The dielectric behavior of PVA/PSSA/Co3O4 nanocomposite films was examined by varying the content of Co3O4 nanoparticles in the frequency and temperature range of 100 Hz–1 MHz and 30–150°C, respectively. The 15 wt% of Co3O4 nanoparticles in the PVA/PSSA/Co3O4 nanocomposite films have a high dielectric constant (ɛ) of 511.66 and a relatively high dielectric loss (tan δ) of 1440.25 at low frequency and at 60°C, respectively. In addition, the high AC conductivity (σac) obtained for the 15 wt% of Co3O4 nanoparticles was found to be 1.66 × 10−5 Scm−1. The improvement in the dielectric performance of PVA/PSSA/Co3O4 nanocomposite films evidenced that they could be promising materials for microwave absorption applications.