Effect of temperature on dielectric properties of polyvinylpyrrolidone/ polyacrylamide blend films at microwave frequency

Abstract

In this paper, dielectric constant (ε_r), dielectric loss (ε_i), loss tangent (tanδ), relaxation time (τ), ac conductivity (σ_ac), extinction coefficient (K) and refractive index (η) of polyvinylpyrrolidone (PVP), polyacrylamide (PAM) and their blend films have been studied in the temperature range 293-393 K at 9.01 GHz microwave frequency. The temperature and frequency dependent σ_ac of film samples is calculated using the dielectric parameters. The variation of ε_i, tanδ, K, σ_ac, η and τ showed a decreasing trend with increasing temperature. It is also observed that the temperature dependency of ε_r is insignificant at this frequency but its value for the film samples increases with the increasing concentration of PVP in the blend. The DSC measurements show miscible behaviour of PVP/PAM blends.