Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
817438 | Composites Part B: Engineering | 2015 | 9 Pages |
Abstract
Composites of epoxy resin with high percentage of silica fillers (66%) are designed to improve mechanical and electrical properties of transformers used in railway application. FTIR, (DRX and FE-SEM) and absorption/desorption phenomena are used to investigate the structure, the morphology and the diffusion of water in the microcomposites, respectively. Good dispersion of silica filler with size less than 10 μm was assessed by SEM, although some clustering (agglomerates) of greater than 1 μm was observed. The absorption water in the microcomposite obeys to the first Fickian law and shows saturation water of 0.6%. The calculation of the diffusion coefficient of water leads to a value of 2.9*10â12 m2 sâ1 in the studied system. Relaxation times of α-relaxation and ionic conduction relaxation processes are determined. A correlation is observed between the ionic conductivity and dielectric relaxation processes. The dc-current behavior shows a change in the conduction mechanism from electronic conduction below the Tg to ionic conduction above the Tg. Shallow traps of 0.54 eV and deep traps of 2.21 eV are determined below and above the Tg, respectively. The TSC analysis confirms the VFT behavior of the α-relaxation of the microcomposite as obtained by the dielectric spectroscopy.
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Physical Sciences and Engineering
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Engineering (General)
Authors
Kahouli Abdelkader, Rain Pascal, Lesaint Olivier, Rigaud Céline,