Dielectric and hydration properties of segmental polyurethanes

Raftopoulos, K; Zegkinoglou, L; Kanapitsas, A; Kripotou, S; Christakis, I; Vassilikou-Dova, A; Pissis, P; Savelyev, Y

dc.contributor.author	Raftopoulos, K	en
dc.contributor.author	Zegkinoglou, L	en
dc.contributor.author	Kanapitsas, A	en
dc.contributor.author	Kripotou, S	en
dc.contributor.author	Christakis, I	en
dc.contributor.author	Vassilikou-Dova, A	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Savelyev, Y	en
dc.date.accessioned	2014-03-01T01:53:57Z
dc.date.available	2014-03-01T01:53:57Z
dc.date.issued	2004	en
dc.identifier.issn	1618-7229	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/27145
dc.subject.classification	Polymer Science	en
dc.subject.other	CHAIN-END GROUPS	en
dc.subject.other	BLOCK-COPOLYMERS	en
dc.subject.other	MICROPHASE SEPARATION	en
dc.subject.other	POLY(METHYL METHACRYLATE)	en
dc.subject.other	MOLECULAR MOBILITY	en
dc.subject.other	GLASS-TRANSITION	en
dc.subject.other	BETA-RELAXATION	en
dc.subject.other	MORPHOLOGY	en
dc.subject.other	POLYMERS	en
dc.subject.other	EXTENDERS	en
dc.title	Dielectric and hydration properties of segmental polyurethanes	en
heal.type	journalArticle	en
heal.identifier.secondary	043	en
heal.language	English	en
heal.publicationDate	2004	en
heal.abstract	Novel polyurethanes (PUs), based on oligo(oxytetramethylene glycol), 4,4'-diphenylmethanediisocyanate and 1,1-dimethylhydrazine as chain extender, were prepared in a two-step process. The ratio prepolymer (PP) to chain extender (CE) was systematically varied in extreme ranges, from 1:1 to 10:1. Dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC) techniques were employed to investigate molecular dynamics and to conclude on microphase separation (MS). In that respect TSDC was proven to be very powerful, in particular as far as the investigation of the interfacial Maxwell-Wagner-Sillars polarization is concerned. Additional information on micromorphology is obtained from water sorption/diffusion measurements. A part of the results suggest that MS improves with increasing the PP:CE ratio. The whole body of results can be explained if, at the same time, it is assumed that a branched structure is developed for samples out of stoichiometry and branching increases with increasing the PP:CE ratio. Preliminary experiments with solutions of the PUs in organic solvents provide support for that assumption.	en
heal.publisher	EUROPEAN POLYMER FEDERATION	en
heal.journalName	E-POLYMERS	en
dc.identifier.isi	ISI:000222359100001	en