Influence of high levels of water absorption on the resistivity and dielectric permittivity of epoxy composites

• Published in: Polymer testing Vol. 24; no. 6; pp. 799 - 804
• Main Authors: Gonon, P., Pham Hong, T., Lesaint, O., Bourdelais, S., Debruyne, H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2005; Elsevier
• Subjects: Applied sciences; Dielectric properties; Electric power; Engineering Sciences; Epoxy composites; Exact sciences and technology; Forms of application and semi-finished materials; Humidity ageing; Laminates; Polymer industry, paints, wood; Technology of polymers; Epoxy composites; Dielectric properties; Humidity ageing; Dielectric loss; Electrical properties; Laminate; Fiber reinforced material; Epoxy resin; Experimental study; Mineral fiber; Modeling; Hybrid composite; Composite material; Humidity effect; Electric insulating material; Electric resistivity; Artificial ageing; Percolation; Water absorption; Glass fiber; Permittivity; Comparative study; Mica
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2005.02.001

We studied the effects of water absorption (up to 1 wt%) on the dielectric properties of mica/glass/epoxy laminated composites used for high-voltage insulation. The DC resistivity, the dielectric constant and the dielectric loss were studied in the 10 −2–10 6 Hz range, as a function of water uptake. The dielectric characteristics are strongly affected by water ingress. Upon water sorption the resistivity decreases by several orders of magnitude. Its variation is well described by a percolation law. The low-frequency permittivity rises to very large values. The large increase in the permittivity is related to an electrode polarisation mechanism.