Dielectric studies of chain dynamics in homogeneous semi-interpenetrating polymer networks

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dc.contributor.author Georgoussis, G en
dc.contributor.author Kyritsis, A en
dc.contributor.author Bershtein, VA en
dc.contributor.author Fainleib, AM en
dc.contributor.author Pissis, P en
dc.date.accessioned 2014-03-01T01:15:33Z
dc.date.available 2014-03-01T01:15:33Z
dc.date.issued 2000 en
dc.identifier.issn 0887-6266 en
dc.identifier.uri https://dspace.lib.ntua.gr/xmlui/handle/123456789/13581
dc.subject semi-interpenetrating polymer networks en
dc.subject dynamic heterogeneities en
dc.subject dielectric relaxation en
dc.subject glass transition en
dc.subject fragility en
dc.subject microphase separation en
dc.subject.classification Polymer Science en
dc.subject.other GLASS-TRANSITION en
dc.subject.other MISCIBLE BLENDS en
dc.subject.other LINEAR POLYURETHANE en
dc.subject.other POLY(VINYL METHYL-ETHER) en
dc.subject.other SEGMENTAL RELAXATION en
dc.subject.other MOLECULAR MOBILITY en
dc.subject.other POLYSTYRENE en
dc.subject.other SPECTROSCOPY en
dc.subject.other MOTION en
dc.title Dielectric studies of chain dynamics in homogeneous semi-interpenetrating polymer networks en
heal.type journalArticle en
heal.identifier.primary 10.1002/1099-0488(20001201)38:23<3070::AID-POLB90>3.0.CO;2-M en
heal.identifier.secondary http://dx.doi.org/10.1002/1099-0488(20001201)38:23<3070::AID-POLB90>3.0.CO;2-M en
heal.language English en
heal.publicationDate 2000 en
heal.abstract Semi-interpenetrating polymer networks (semi-PPNs) were prepared from linear polyurethane (PUR) and polycyanurate (PCN) networks. Wide-angle X-ray scattering measurements showed that the IPNs were amorphous, and differential scanning calorimetry and small-angle X-ray scattering measurements suggested that they were macroscopically homogeneous. Here we report the results of detailed studies of the molecular mobility in IPNs with PUR contents greater than or equal to 50% via broadband dielectric relaxation spectroscopy (10(-2)-10(9) Hz, 210-420 K) and thermally stimulated depolarization current techniques (77-320 K). Both techniques gave a single alpha relaxation in the IPNs, shifting to higher temperatures in isochronal plots with increasing PCN content, and provided measures for the glass-transition temperature (T-g) close to and following the calorimetric T-g. The dielectric response in the IPNs was dominated by PUR. The segmental alpha relaxation, associated with the glass transition and, to a lesser extent, the local secondary beta and gamma relaxations were analyzed in detail with respect to the timescale, the shape of the response, and the relaxation strength. The alpha relaxation became broader with increasing PCN content, the broadening being attributed to concentration fluctuations. Fragility decreased in the IPNs in comparison with PUR, the kinetic free volume at T-g increased, and the relaxation strength of the alpha relaxation, normalized to the same PUR content, increased. The results are discussed in terms of the formation of chemical bonds between the components, as confirmed by IR, and the reduced packing density of PUR chains in the IPNs. (C) 2000 John Wiley & Sons, Inc. en
heal.publisher JOHN WILEY & SONS INC en
dc.identifier.doi 10.1002/1099-0488(20001201)38:23<3070::AID-POLB90>3.0.CO;2-M en
dc.identifier.isi ISI:000165258000009 en
dc.identifier.volume 38 en
dc.identifier.issue 23 en
dc.identifier.spage 3070 en
dc.identifier.epage 3087 en

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