Dielectric properties of graphene/nano-Fe2O3 filled poly (vinyl alcohol)/ Chitosan blends

Abstract

Novel nanocomposites based on Poly (vinyl alcohol) (PVA), Chitosan (CS), Graphene quantum dots (GQDs) and iron oxide (Fe2O3) nanoparticles (NPs) have been synthesized by solution casting method. The structural mod-ifications and morphological studies were carried out by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Scanning electron microscopy/Energy-dispersive X-ray (SEM/EDX) techniques. The results confirm the microscopic interactions and sphere-like morphology of the nanocomposites due to the presence of GQDs and Fe2O3 within the polymer blend. The thermal stability with almost 25% leftover residue for higher nanofillers loading in the nanocomposite was estimated by thermo-gravimetric analysis (TGA). Moreover, the frequency and temperature-dependent dielectric properties were investigated. The dielectric constant and loss tangent values are greatly influenced by reinforcement of GQDs/Fe2O3 and the obtained values were in the range of-104 and-101, respectively at 150 degrees C and 50 Hz. The rise in ac conductivity i.e., 9.8 x 10-4 (S/m) with increasing nanofiller loadings suggests the reduction in capacitive reactance and impedance. However, the semi-circular arcs are observed in the cole-cole plot where the fitted impedance data along with the equivalent circuit is also presented. The reduction of bulk resistance and impedance on increasing the nanofiller loadings with enhanced dielectric properties signifies the use of PVA/CS/GQDs/Fe2O3 nanocomposites as a potential material for energy storage applications.