کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1250578 1496031 2016 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Polymer chain dynamics in epoxy based composites as investigated by broadband dielectric spectroscopy
ترجمه فارسی عنوان
پویایی زنجیره پلیمر در کامپوزیت های اپوکسی بر اساس طیف سنجی دیود الکتریکی پهنای باند مورد بررسی قرار گرفته است
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی (عمومی)
چکیده انگلیسی

Epoxy 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.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Arabian Journal of Chemistry - Volume 9, Issue 2, March 2016, Pages 305–315
نویسندگان
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