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DSC, dielectric and dynamic mechanical behavior of two- and three-component ordered polyurethanes

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dc.contributor.author Valentova, H en
dc.contributor.author Nedbal, J en
dc.contributor.author Ilavsky, M en
dc.contributor.author Pissis, P en
dc.date.accessioned 2014-03-01T01:22:12Z
dc.date.available 2014-03-01T01:22:12Z
dc.date.issued 2005 en
dc.identifier.issn 0032-3861 en
dc.identifier.uri https://dspace.lib.ntua.gr/xmlui/handle/123456789/16491
dc.subject Dielectric and mechanical spectroscopy en
dc.subject Liquid-crystalline polyurethanes en
dc.subject.classification Polymer Science en
dc.subject.other Differential scanning calorimetry en
dc.subject.other Glass transition en
dc.subject.other Heating en
dc.subject.other Hydroxylation en
dc.subject.other Liquid crystals en
dc.subject.other Mechanical properties en
dc.subject.other Permittivity en
dc.subject.other Polybutadienes en
dc.subject.other Stoichiometry en
dc.subject.other Diisocyanates (DI) en
dc.subject.other Dynamic mechanical behavior en
dc.subject.other Liquid crystalline (LC) polyurethanes en
dc.subject.other Stoichiometric ratios en
dc.subject.other Polyurethanes en
dc.subject.other polyurethane en
dc.title DSC, dielectric and dynamic mechanical behavior of two- and three-component ordered polyurethanes en
heal.type journalArticle en
heal.identifier.primary 10.1016/j.polymer.2005.02.055 en
heal.identifier.secondary http://dx.doi.org/10.1016/j.polymer.2005.02.055 en
heal.language English en
heal.publicationDate 2005 en
heal.abstract Liquid crystalline (LC) polyurethanes were made from two diisocyanates (flexible HMDI and stiff TDI) (DIs), mesogenic diol (D) and a polybutadiene-diol (B) with stoichiometric ratios of reactive hydroxy (OH) and isocyanate (NCO) groups ((NCO)(DI)/((OH)(D) + (OH)(B))= 1/1). Two- (B/DIs, D/DIs) and three-component ((D + B)/DIs, D/B = 1/1 by weight) polymers were prepared and their dielectric, dynamic mechanical and DSC behavior was investigated. For neat B, the glass transition temperature T-gB (∼ -46 ° C) was detected. Two-component B/HMDI and B/TDI polymers have exhibited a homogeneous structure with the glass transition temperatures T-gU ∼ - 9 and 2 ° C. On the other hand, for D/DI polymers on cooling from the melt and subsequent heating the glass transitions at T-gU∼ 41 ° C (D/HMDI) and 58 ° C (D/TDI) together with nematic and smectic mesophases were found. In three-component systems, additional glass transitions at T-gB ∼ -41 ° C (B/D/HMDI) and -31 ° C (B/D/TDI) were observed. This means that the polymers exhibit a distinct two-phase structure with soft polybutadiene (B) and hard polyurethane (D/DI) phases. In hard polyurethane phase, the glass transitions at T-gU and LC mesophases similar to those found in two-component D/DI polyurethanes were detected. Dielectric and dynamic mechanical results correlate well with DSC measurements. © 2005 Elsevier Ltd. All rights reserved. en
heal.publisher ELSEVIER SCI LTD en
heal.journalName Polymer en
dc.identifier.doi 10.1016/j.polymer.2005.02.055 en
dc.identifier.isi ISI:000229598400024 en
dc.identifier.volume 46 en
dc.identifier.issue 12 en
dc.identifier.spage 4175 en
dc.identifier.epage 4182 en


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