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AuthorHassan, Mohammad K.
AuthorTucker, Samuel J.
AuthorAbukmail, Ahmed
AuthorWiggins, Jeffrey S.
AuthorMauritz, Kenneth A.
Available date2016-09-25T11:15:07Z
Publication Date2016-03
Publication NameArabian Journal of Chemistryen_US
Identifierhttp://dx.doi.org/10.1016/j.arabjc.2015.07.016
CitationMohammad K. Hassan, Samuel J. Tucker, Ahmed Abukmail, Jeffrey S. Wiggins, Kenneth A. Mauritz, Polymer chain dynamics in epoxy based composites as investigated by broadband dielectric spectroscopy, Arabian Journal of Chemistry, Volume 9, Issue 2, March 2016, Pages 305-315.
ISSN18785352
URIhttp://www.sciencedirect.com/science/article/pii/S1878535215002385
URIhttp://hdl.handle.net/10576/4768
AbstractEpoxy networks of the diglycidyl ether of bisphenol A (DGEBA) were prepared using 3,3′- and 4,4′-diaminodiphenyl sulfone isomer crosslinkers. Secondary relaxations and the glass transitions of resultant networks were probed using broadband dielectric spectroscopy (BDS). A sub-Tgγ relaxation peak for both networks shifts to higher frequencies (f) with increasing temperature in Arrhenius fashion, both processes having the same activation energy and being assigned to phenyl ring flipping in DGEBA chains. A β relaxation is assigned to local motions of dipoles that were created during crosslinking reactions. 4,4′-based networks exhibited higher Tg relative to 3,3′-based networks as per dynamic mechanical as well as BDS analyses. The Vogel–Fulcher–Tammann–Hesse equation fitted well to relaxation time vs. temperature data and comparison of Vogel temperatures suggests lower free volume per mass for the 3,3′-based network. The Kramers–Krönig transformation was used to directly calculate dc-free ɛ″ vs. f data from experimental ɛ′ vs. f data. Distribution of relaxation times (DRT) curves are bi-modal for the 3,3′-crosslinked resin suggesting large-scale microstructural heterogeneity as opposed to homogeneity for the 4,4′-based network whose DRT consists of a single peak.
SponsorU.S. Office of Naval Research, Award N00014-07-1-1057 and fellowship support from the Department of Education Graduate Assistance in Areas of National Need Award P200A090066. Qatar University's Center for Advanced Materials' Start-Up grant.
Languageen
PublisherElsevier B.V.
SubjectDielectric spectroscopy
SubjectEpoxy networks of the diglycidyl ether of bisphenol A
Subject3,3′ and 4,4′-diaminodiphenyl sulfone isomers
SubjectChain motions
SubjectVogel temperature
SubjectKramers–Krönig transformation
TitlePolymer chain dynamics in epoxy based composites as investigated by broadband dielectric spectroscopy
TypeArticle
Pagination305-315
Issue Number2
Volume Number9
Open Access user License http://creativecommons.org/licenses/by-nc-nd/4.0/


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