Dielectric properties of polyacrylamide and its utilization as a hydrogel

Some of the dielectric properties of polyacrylamide are given such as the v ariation of the dielectric constant, epsilon', and the dielectric loss, eps ilon ", and the power factor tan delta with the applied frequency from 10(5 ) to 10(7) Hz within the temperature range 20-50 degrees C. The dielectric dispersion and absorption bands appear within these ranges of frequencies a nd temperatures. The relaxation process is explained and discussed, also th e relaxation limes are calculated and the activation energy and entropy cha nge of dielectric relaxation are calculated from the usual rate equation an d discussed. The process of polymerization of polyacrylamide is explained t hrough comparing the dielectric properties of the monomer (acrylamide) and the polymer. Out of two approaches to obtain a hydrogel from polyacrylamide , the physical approach is thoroughly investigated and discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.