Electrothermal Ageing of Epoxy Nanocomposites

Preetha, P and Thomas, Joy M and Ranjan, Rajeev (2012) Electrothermal Ageing of Epoxy Nanocomposites. In: IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION, 19 (6). pp. 2081-2089.

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Abstract

Constant stress accelerated ageing experiments were conducted on unfilled epoxy and epoxy alumina nanocomposites with different filler loadings of 0.1, 1 and 5 wt%. Electrical (6 kV/mm), thermal (60 degrees C) and combined electrothermal (6 kV/mm and 60 degrees C) ageing experiments were performed for a duration of 250 h. The leakage current through the samples were continuously monitored and the variation in the tan delta values with ageing duration was also monitored. It was observed that the increase in the tan delta value with ageing duration was less for the epoxy alumina nanocomposites as compared to the unfilled epoxy. Dielectric spectroscopy measurements were performed on the samples before and after the ageing in the frequency range of 10(-2) to 10(6) Hz. The permittivity and tan delta values were found to increase in the low frequency range. The volume resistivity of unfilled epoxy and epoxy alumina nanocomposites were also measured before and after the ageing. The volume resistivity improved marginally for the thermally aged samples, but reduced for the electrically aged and the electrothermally aged samples. The decrease in the value of volume resistivity was more for the multistress aged unfilled epoxy samples as compared to the multistress aged epoxy alumina nanocomposites. It was also observed that the unfilled epoxy samples having a higher value of tan delta failed first. The time to failure of the samples showed an increasing trend with an increase in the nano filler loading of epoxy alumina nanocomposites.

Item Type:	Journal Article
Publication:	IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
Publisher:	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Additional Information:	Copyright for this article belongs to IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, USA
Keywords:	Multistress ageing;electrothermal ageing;polymer nanocomposites;epoxy
Department/Centre:	Division of Electrical Sciences > Electrical Engineering Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	19 Feb 2013 05:11
Last Modified:	19 Feb 2013 05:11
URI:	http://eprints.iisc.ac.in/id/eprint/45829

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