Morphological changes in segmented polyurethane elastomers by varying the NCO/OH ratio

Spathis, G; Niaounakis, M; Kontou, E; Apekis, L; Pissis, P; Christodoulides, C

dc.contributor.author	Spathis, G	en
dc.contributor.author	Niaounakis, M	en
dc.contributor.author	Kontou, E	en
dc.contributor.author	Apekis, L	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Christodoulides, C	en
dc.date.accessioned	2014-03-01T01:09:59Z
dc.date.available	2014-03-01T01:09:59Z
dc.date.issued	1994	en
dc.identifier.issn	0021-8995	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/11279
dc.subject.classification	Polymer Science	en
dc.subject.other	Calorimetry	en
dc.subject.other	Crosslinking	en
dc.subject.other	Molecular weight	en
dc.subject.other	Morphology	en
dc.subject.other	Polarization	en
dc.subject.other	Polymerization	en
dc.subject.other	Polyurethanes	en
dc.subject.other	Separation	en
dc.subject.other	Spectroscopy	en
dc.subject.other	Differential scanning calorimetry	en
dc.subject.other	Fourier transform infrared spectroscopy	en
dc.subject.other	Hydrogen bonding	en
dc.subject.other	Phase separation	en
dc.subject.other	Relaxation mechanism	en
dc.subject.other	Segmented polyurethane elastomers	en
dc.subject.other	Thermally stimulated depolarization current	en
dc.subject.other	Thermoplastic polyurethane	en
dc.subject.other	Elastomers	en
dc.title	Morphological changes in segmented polyurethane elastomers by varying the NCO/OH ratio	en
heal.type	journalArticle	en
heal.identifier.primary	10.1002/app.1994.070540701	en
heal.identifier.secondary	http://dx.doi.org/10.1002/app.1994.070540701	en
heal.language	English	en
heal.publicationDate	1994	en
heal.abstract	The morphological changes induced to segmented polyurethane elastomers by varying the NCO/OH ratio during the second step of polymerization, while keeping constant the total hard-segment content (similar to 30%), were studied by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and the thermally stimulated depolarization current method (TSDC). The DSC results gave evidence for the existence of phase separation in thermoplastic polyurethanes, whereas the elastomeric ones appeared to form a more homogeneous network. The FTIR results gave additional evidence regarding phase separation by detecting the strength of the hydrogen bonds. Moreover, an attempt was made to assess the relative contribution made to the hydrogen bonding in such systems by the two potential accepters: ester and urethane carbonyls. The TSDC results gave a relaxation mechanism that is due to interfacial (Maxwell-Wagner-Sillars) polarization, providing evidence of the existence of an interfacial phase. The introduced secondary chemical cross-links was found to affect mainly the irregularly packed hard domains and to form a more homogeneous network at higher values of the NCO/OH ratio. (C) 1994 John Wiley and Sons, Inc.	en
heal.publisher	John Wiley & Sons Inc, New York, NY, United States	en
heal.journalName	Journal of Applied Polymer Science	en
dc.identifier.doi	10.1002/app.1994.070540701	en
dc.identifier.isi	ISI:A1994PM24800001	en
dc.identifier.volume	54	en
dc.identifier.issue	7	en
dc.identifier.spage	831	en
dc.identifier.epage	842	en