Polymer dynamics in rubbery epoxy networks/ polyhedral oligomeric silsesquioxanes nanocomposites

Kourkoutsaki, T; Logakis, E; Kroutilova, I; Matejka, L; Nedbal, J; Pissis, P

dc.contributor.author	Kourkoutsaki, T	en
dc.contributor.author	Logakis, E	en
dc.contributor.author	Kroutilova, I	en
dc.contributor.author	Matejka, L	en
dc.contributor.author	Nedbal, J	en
dc.contributor.author	Pissis, P	en
dc.date.accessioned	2014-03-01T01:31:40Z
dc.date.available	2014-03-01T01:31:40Z
dc.date.issued	2009	en
dc.identifier.issn	0021-8995	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19877
dc.subject	Dielectric properties	en
dc.subject	Nanocomposites	en
dc.subject	Polyhedral oligomeric silsesquioxanes (POSS)	en
dc.subject	Rubbery epoxy networks	en
dc.subject	Segmental dynamics	en
dc.subject.classification	Polymer Science	en
dc.subject.other	Broadband dielectric relaxation spectroscopy	en
dc.subject.other	Chain contours	en
dc.subject.other	Constant frequency	en
dc.subject.other	Covalently bound	en
dc.subject.other	Density Measurements	en
dc.subject.other	Dielectric techniques	en
dc.subject.other	Diglycidyl ether of bisphenol-A	en
dc.subject.other	Glassy state	en
dc.subject.other	Jeffamine	en
dc.subject.other	Molecular origins	en
dc.subject.other	Molecular packings	en
dc.subject.other	Normal modes	en
dc.subject.other	Poly(oxypropylene) diamine	en
dc.subject.other	Polyhedral oligomeric silsesquioxanes	en
dc.subject.other	Polyhedral oligomeric silsesquioxanes (POSS)	en
dc.subject.other	Polymer dynamics	en
dc.subject.other	Rubbery epoxy networks	en
dc.subject.other	Segmental dynamics	en
dc.subject.other	Thermally stimulated depolarization currents	en
dc.subject.other	Amines	en
dc.subject.other	Ceramic capacitors	en
dc.subject.other	Dielectric properties	en
dc.subject.other	Differential scanning calorimetry	en
dc.subject.other	Dynamics	en
dc.subject.other	Ethers	en
dc.subject.other	Free volume	en
dc.subject.other	Glass transition	en
dc.subject.other	Molecular dynamics	en
dc.subject.other	Nanocomposites	en
dc.subject.other	Phenols	en
dc.subject.other	Reconnaissance aircraft	en
dc.subject.other	Epoxy resins	en
dc.subject.other	dielectric property	en
dc.subject.other	epoxy resin	en
dc.subject.other	nanocomposite	en
dc.subject.other	oligomer	en
dc.subject.other	plasticizing agent	en
dc.subject.other	polymer	en
dc.subject.other	synthetic rubber	en
dc.title	Polymer dynamics in rubbery epoxy networks/ polyhedral oligomeric silsesquioxanes nanocomposites	en
heal.type	journalArticle	en
heal.identifier.primary	10.1002/app.30225	en
heal.identifier.secondary	http://dx.doi.org/10.1002/app.30225	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	Dielectric techniques, including thermally stimulated depolarization currents (TSDC, -150 to 30 degrees C) and, mainly, broadband dielectric relaxation spectroscopy (DRS, 10(-2) - 10(6) Hz, -150 to 150 degrees C) were employed, next to differential scanning calorimetry (DSC), to investigate molecular dynamics in rubbery epoxy networks prepared from diglycidyl ether of Bisphenol A (DGEBA) and poly (oxypropylene)diamine (Jeffamine D2000, molecular mass 2000) and modified with polyhedral oligomeric silsesquioxanes (POSS) units covalently bound to the chains as dangling blocks. Four relaxations were detected and analyzed: in the order of increasing temperature at constant frequency, two local, secondary gamma and beta relaxations in the glassy state, the segmental alpha relaxation associated with the glass transition and the normal mode relaxation, related with the presence of a dipole moment component along the Jeffamine chain contour. Measurements on pure Jeffamine D2000 helped to clarify the molecular origin of the relaxations observed. A significant reduction of the magnitude and a slight acceleration of the alpha and of the normal mode relaxations were observed in the modified networks. These results suggest that a fraction of polymer is immobilized, probably at interfaces with POSS, due to constraints imposed by the covalently bound rigid nanoparticles, whereas the rest exhibits a slightly faster dynamics due to increaseof free volume resulting from loosened molecular packing of the chains (plasticization by the bulky TOSS units). The increase of free volume is rationalized by density measurements. (C) 2009 Wiley Periodicals, Inc. I Appl Polym Sci 113: 2569-2582, 2009.	en
heal.publisher	JOHN WILEY & SONS INC	en
heal.journalName	Journal of Applied Polymer Science	en
dc.identifier.doi	10.1002/app.30225	en
dc.identifier.isi	ISI:000266945300061	en
dc.identifier.volume	113	en
dc.identifier.issue	4	en
dc.identifier.spage	2569	en
dc.identifier.epage	2582	en