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

In this paper, dielectric constant (εr), dielectric loss (εi), loss tangent (tanδ), relaxation time (τ), ac conductivity (σac), 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 σac of film samples is calculated using the dielectric parameters. The variation of εi, tanδ, K, σac, η and τ showed a decreasing trend with increasing temperature. It is also observed that the temperature dependency of εr 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