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

Georgoussis, G; Kyritsis, A; Bershtein, VA; Fainleib, AM; Pissis, P

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	POLYURETHANE BLOCK-COPOLYMERS	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
heal.journalName	JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS	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