Dielectric dispersion studies of poly(vinyl alcohol) in aqueous solutions

The dielectric constant epsilon' and loss factor epsilon " of deionized wat er and poly(vinyl alcohol) in aqueous solutions are measured in the frequen cy region 200 MHz to 20 GHz at four different temperatures (25, 35, 45 and 55 degreesC). Complex plane plots (ie epsilon " vs epsilon') are drawn to o btain the static dielectric constant epsilon (0), high frequency dielectric constant epsilon (infinity), distribution parameter alpha and average rela xation time tau (0). The variations of dielectric constants with increasing solvent concentration and temperature are discussed in terms of solute-sol vent and solute-solute interactions. The average relaxation time tau (0) of poly(vinyl alcohol) aqueous solutions is found to the very short. It is al so observed that the relaxation time is almost independent of the viscosity of the solution. The effect of water concentration on macromolecular size, shape and flexibility of the molecular chain are discussed using the obser ved values of dielectric relaxation times at different temperatures. The po ssibility of multiple dielectric dispersion is also discussed with concentr ation variation. (C) 2000 Society of Chemical Industry.