Abstract

EFFECT OF PACKING DENSITY AND TEMPERATURE ON DIELECTRIC PARAMETERS OF LAC IN MICROWAVE REGION

Govind A. Karhale*

Abstract

To obtain useful information on biophysical properties of various kinds of natural products, the study of dielectric behaviour from microwave absorption is of great value. The dielectric parameters are generally dependent on frequency, temperature, packing density and other factors such as material structure and composition. The behaviour of dielectric substance is changed by the application of external electric field. The important concept in dielectric theory is that of an electric dipole moment which is measure of electrostatic effect of a pair of opposite charges separated by a finite distance. The present paper examines the effect of packing density and temperature on dielectric parameters of natural Lac from Samanea saman tree (Rain tree). The wave guide cell was designed for holding Lac sample in the form of powder. The reflectometric technique was used for the measurement of dielectric constant and loss factor. Measurement of Lac powders of different packing fractions at 9.85 GHz microwave frequency are reported. The results indicate that, the values of dielectric constant (p), dielectric loss (p), relaxation time (ηp) and conductivity (ζp), increases with the increase of relative packing fraction (δr) 0.9501, 0.9685, 1.000, and decreases with the increase in temperature 00c, 100c, 200c and 300c. The experimental values have been used to obtain transformation to 100% solid bulk, using co-relation formulae of Landu-Lifshitz, Looyanga and Bottcher. The results show that there is a fair agreement between the experimental and theoretical values of dielectric constant and dielectric loss.

Keywords: Lac, Dielectric constant, Relaxation time, Conductivity, Packing density.