Dielectric relaxation in hydroxyethyl cellulose

This paper presents the results of the dielectric analysis of hydroxyethyl cellulose (HEC) in the temperature range 100-350 K and in the frequency range 20 Hz-l MHz. The results show a distinct broad relaxation process in the temperature range 150-250 K with activation energy of about 33.4 MJ/kmol. The strength of the relaxation, epsilon(s) - epsilon infinity, increases only slightly with temperature and the apparent increase of the height of the relaxation maximum is attributed to an increase of the co-operativity parameter alpha. This increase of alpha is interpreted as decrease of the co-operativity of dipole motions with increasing temperature. The origin of the relaxation is ascribed to the reorientation of double ethylene oxide groups or part of these. (C) 2000 Elsevier Science Ltd. All rights reserved.