Structural, electrical and dielectric studies of nano-composite polymer blend electrolyte films based on (70-x) PVA-x PVP-NaI-SiO2

Nano-composite polymer electrolytes (NCPEs) films based on PVA-PVP-NaI-SiO2 have been prepared using solution casting technique. Investigation of prepared films have been made using various experimental techniques like x-ray diffraction (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), differential scanning calorimetric (DSC) and ac impedance spectroscopy. XRD determines the structural properties and shows the significant variation in the characteristic peaks related to semi-crystalline/amorphous phase of different PVA-PVP polymer blend ratio for fixed loading of NaI and SiO2. Complexation of PVA-PVP polymer blend with NaI and SiO2 has been confirmed by ATR-FTIR analysis. Variation in glass transition temperature (T-g) and melting temperature (T-m) of PVA-PVP-NaI-SiO2 NCPE system having various concentration of PVP were observed by DSC analysis. It has been observed that ac conductivity spectra strongly obeys the Jonscher's universal power law [sigma = sigma(dc) + Af(n)] with power exponent, n < 1. The dielectric permittivity (epsilon'&epsilon '') and electric modulus (M'& M '') measurements were performed in a wide frequency range (10 mHz-10 MHz). Variation of conductivity with temperature shows that the ion conduction and polymer segmental motions are closely related and are governed by Arrhenius mechanism. A couple of peaks observed in loss tangent (tan delta) shows two types of relaxation processes interpreted in terms of dipole segmental motion (alpha-relaxation) and side chain dipole group motion (beta-relaxation).