Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethyl cellulose

Dielectric capacities and losses were measured, in the temperature (50-170 degrees C) and frequency (01-100 kHz range), for undoped and acrylic acid ( AA) doped ethyl cellulose (EC) films (thickness about 20 mu m) with progres sive increase in the concentration of dopant in the polymer matrix. The var iation of capacity with temperature is attributed to thermal expansion in t he lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature (T-g) and random thermal moti on of molecules above T-g. The dielectric losses exhibit a broad peak. Dopi ng with AA is found to affect the magnitude and position of the peak. AA is found to have a two-fold action. Firstly, it enhances the chain mobility a nd secondly, it increases the dielectric loss by forming charge transfer co mplexes.