Dielectric behaviour of cellulose acetate-based polymer electrolytes

Abstract

The present work deals with the findings on the dielectric behaviour of cellulose acetate (CA) and its complexes consisting of ammonium tetrafluoroborate (NH₄BF₄) and polyethylene glycol with a molecular weight of 600 g/mol (PEG₆₀₀) that were prepared using the solution casting method. The highest σ obtained for CA-NH₄BF₄ film was 2.18 × 10⁻⁷ S cm⁻¹ and enhanced to 1.41 × 10⁻⁵ S cm⁻¹ with the addition of 30 wt.% PEG₆₀₀. The dielectric behaviours of the selected samples were analyzed using complex impedance Z*, complex admittance A*, complex permittivity ɛ*, and complex electric modulus M*-based frequency and temperature dependence in the range of 10 Hz–1 MHz and 303–363 K, respectively. The variation in dielectric permittivity (ε _r and ε _i) as a function of frequency at different temperatures exhibits a dispersive behaviour at low frequencies and decays at higher frequencies. The variation in dielectric permittivity as a function of temperature at different frequencies is typical of polar dielectrics in which the orientation of dipoles is facilitated with the rising temperature, and thereby the permittivity is increased. Modulus analysis was also performed to understand the mechanism of electrical transport process, whereas relaxation time was determined from the variation in loss tangent with temperature at different frequencies.