Dielectric and hydration properties of segmental polyurethanes

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

dc.contributor.author	Raftopoulos, K	en
dc.contributor.author	Zegkinoglou, I	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	2014-03-01T01:20:14Z
dc.date.available	2014-03-01T01:20:14Z
dc.date.issued	2004	en
dc.identifier.issn	1432-8917	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15863
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-18644371574&partnerID=40&md5=d11da1bdfbb6f19a4aaa58ba7bba2911	en
dc.subject	polyurethanes	en
dc.subject	microphase separation	en
dc.subject	dielectric techniques alpha-relaxation	en
dc.subject	interfacial polarization	en
dc.subject	hydration properties	en
dc.subject.classification	Materials Science, Multidisciplinary	en
dc.subject.other	Crystallization	en
dc.subject.other	Differential scanning calorimetry	en
dc.subject.other	Diffusion	en
dc.subject.other	Hydration	en
dc.subject.other	Molecular dynamics	en
dc.subject.other	Morphology	en
dc.subject.other	Organic solvents	en
dc.subject.other	Stoichiometry	en
dc.subject.other	Thermal effects	en
dc.subject.other	Chain extender (CE)	en
dc.subject.other	Microphase separation	en
dc.subject.other	Segmental polyurethanes	en
dc.subject.other	Thermal stimulation	en
dc.subject.other	Polyurethanes	en
dc.title	Dielectric and hydration properties of segmental polyurethanes	en
heal.type	journalArticle	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	MATRICE TECHNOLOGY LIMITED	en
heal.journalName	E-Polymers	en
dc.identifier.isi	ISI:000231696800004	en
dc.identifier.volume	8	en
dc.identifier.issue	3	en
dc.identifier.spage	134	en
dc.identifier.epage	135	en