Tree initiation characteristics of epoxy resin and epoxy/clay nanocomoposite

Stephanie Raetzke, Yoshimichi Ohki, Takahiro Imai, Toshikatsu Tanaka, Josef Kindersberger

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    Abstract

    Tree initiation behavior of an epoxy nanocomposite with 5 wt % nanoclay (layered silicate) was investigated for ac voltage in comparison to neat epoxy resin without fillers. To shorten the time for experiments, 600 Hz was used instead of 60 Hz, as acceleration for tree initiation had been confirmed at 10 kVrms and 14 kVrms between the two frequencies. V-t characteristics for tree initiation rather than tree growth to bridge the electrodes were obtained for conventional type of treeing specimens with an embedded steel needle subjected to voltages from 2 kVrms to 14 kVrms. As a result, it was clarified that tree initiation V-t characteristics were improved by approximately one order of magnitude for the epoxy/nanoclay composite compared to the neat epoxy resin. Initial formation of trees is generally considered to be directly related to the fatigue of matter stressed by electric ac fields at comparatively low field strength. Experimentally obtained prolongation of tree initiation time especially at low electric field can be ascribed to the suppression of such a fatigue through an interaction of injected electrons with nanoscale filler particles or interfaces between nanoscale filler particles and their surrounding polymer matrices. Mechanisms for improvement of time to tree initiation are discussed on the basis of the above concept including a multicore model that some of the authors have proposed.

    Original languageEnglish
    Article number5293962
    Pages (from-to)1473-1480
    Number of pages8
    JournalIEEE Transactions on Dielectrics and Electrical Insulation
    Volume16
    Issue number5
    DOIs
    Publication statusPublished - 2009 Oct

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    Keywords

    • (insulation)
    • Epoxy resin
    • Multi-core model
    • Nanodielectrics
    • Polymer nanocomposite
    • Trees

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering

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