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A detailed study of α-relaxation in epoxy/carbon nanoparticles composites using computational analysis

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Author(s): C. A. Stergiou | A. Z. Stimoniaris | C. G. Delides

Journal: eXPRESS Polymer Letters
ISSN 1788-618X

Volume: 6;
Issue: 2;
Start page: 120;
Date: 2012;
Original page

Keywords: Nanocomposites | carbon black | carbon nanotubes | thermomechanical properties | a-relaxation analysis

ABSTRACT
Nanocomposites were fabricated based on diglycidyl ether of bisphenol A (DGEBA), cured with triethylenetetramine (TETA) and filled with: a) high conductivity carbon black (CB) and b) amino-functionalized multiwalled carbon nanotubes (MWCNTs). The full dynamic mechanical analysis (DMA) spectra, obtained for the thermomechanical characterization of the partially cured DGEBA/TETA/CB and water saturated DGEBA/TETA/MWCNT composites, reveal a complex behaviour as the α-relaxation appears to consist of more than one individual peaks. By employing some basic calculations along with an optimization procedure, which utilizes the pseudo-Voigt profile function, the experimental data have been successfully analyzed. In fact, additional values of sub-glass transition temperature (Ti) corresponding to subrelaxation mechanisms were introduced besides the dominant process. Thus, the physical sense of multiple networks in the composites is investigated and the glass transition temperature Tg is more precisely determined, as the DMA α-relaxation peaks can be reconstructed by the accumulation of individual peaks. Additionally, a novel term, the index of the network homogeneity (IH), is proposed to effectively characterize the degree of statistical perfection of the network.
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