DIELECTRIC-RELAXATION SPECTROSCOPY IN POLY(HYDROXYETHYL ACRYLATES)/WATER HYDROGELS

KYRITSIS, A; PISSIS, P; GRAMMATIKAKIS, J

dc.contributor.author	KYRITSIS, A	en
dc.contributor.author	PISSIS, P	en
dc.contributor.author	GRAMMATIKAKIS, J	en
dc.date.accessioned	2014-03-01T01:10:55Z
dc.date.available	2014-03-01T01:10:55Z
dc.date.issued	1995	en
dc.identifier.issn	0887-6266	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/11496
dc.subject	POLY(HYDROXYETHYL ACRYLATE) HYDROGELS	en
dc.subject	DIELECTRIC RELAXATION	en
dc.subject	CONDUCTIVITY, COMPLEX IMPEDANCE AND ELECTRIC MODULUS	en
dc.subject	ELECTRODE POLARIZATION	en
dc.subject	FRAGILITY	en
dc.subject.classification	Polymer Science	en
dc.subject.other	VITREOUS IONIC CONDUCTORS	en
dc.subject.other	POLY(2-HYDROXYETHYL METHACRYLATE)	en
dc.subject.other	CONDUCTIVITY RELAXATIONS	en
dc.subject.other	ELECTRICAL RELAXATION	en
dc.subject.other	LIQUIDS	en
dc.subject.other	WATER	en
dc.subject.other	POLYMERS	en
dc.subject.other	SOLIDS	en
dc.subject.other	TRANSITION	en
dc.subject.other	DEPENDENCE	en
dc.title	DIELECTRIC-RELAXATION SPECTROSCOPY IN POLY(HYDROXYETHYL ACRYLATES)/WATER HYDROGELS	en
heal.type	journalArticle	en
heal.identifier.primary	10.1002/polb.1995.090331205	en
heal.identifier.secondary	http://dx.doi.org/10.1002/polb.1995.090331205	en
heal.language	English	en
heal.publicationDate	1995	en
heal.abstract	The electrical and dielectric properties of poly(hydroxyethyl acrylate), PHEA, hydrogels were studied by means of dielectric relaxation spectroscopy in wide ranges of frequencies (5-2 X 10(9) Hz), temperatures (173-363 K) and water contents (0.065-0.46, g of water per gram of dry material). The secondary dipolar mechanisms (gamma and beta(sw)) and the dc conductivity mechanism were studied in detail by analyzing the dielectric susceptibility data within the complex permittivity formalism, the modulus formalism, and the complex impedance formalism. For both mechanisms molecular mobility was found to increase with increasing temperature or increasing water content (T-f-h superposition principle). The energy parameters and the shape parameters of the response were determined for both mechanisms at several water contents and temperatures. The temperature dependence of de conductivity was found to change from Vogel-Tamman-Fulcher (VTF) type to Arrhenius type at water contents of ca. 0.30. At water contents lower than about 0.30 the hydrogels are homogeneous whereas at higher water contents a separate water phase appears. In terms of the strong/fragile classification scheme our results suggest that the PHEA hydrogels are fragile systems. (C) 1995 John Wiley and Sons, Inc.	en
heal.publisher	JOHN WILEY & SONS INC	en
heal.journalName	JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS	en
dc.identifier.doi	10.1002/polb.1995.090331205	en
dc.identifier.isi	ISI:A1995RP02600005	en
dc.identifier.volume	33	en
dc.identifier.issue	12	en
dc.identifier.spage	1737	en
dc.identifier.epage	1750	en