Dielectric and carrier transport properties of silicone rubber degraded by gamma irradiation

Daomin Min, Chenyu Yan, Yin Huang, Shengtao Li, Yoshimichi Ohki

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    Silicone rubber (SiR) is used as an insulating material for cables installed in a nuclear power plant. Gamma rays irradiated SiR sheets for various periods at temperatures of 145 and 185 °C, and the resultant changes were analyzed by examining complex permittivity spectra and surface potential decay characteristics. Three different processes, namely, instantaneous polarization, electrode polarization due to the accumulation of ions to form double charge layers at dielectric/electrode interfaces, and DC conduction caused by directional hopping of ions, contribute to the complex permittivity. By fitting the spectra to theoretical equations, we can obtain the dielectric constant at high frequencies, concentration and diffusion coeffcient of ions and DC conductivity for the pristine and degraded samples. The instantaneous polarization becomes active with an increase of dose and ageing temperature. The thermal expansion coeffcient estimated from the temperature dependence of dielectric constant at high frequencies becomes smaller with an increase in dose, which is in good agreement with the experimental results of the swelling ratio. Additionally, trap distributions are calculated from surface potential decay measurements and analyzed to explain the variation in conductivity. Trap energy increases firstly, and then decreases with an increase in dose, leading to a similar change in DC conductivity. It is concluded that generations of both oxidative products and mobile ions, as well as the occurrence of chain scission and crosslinking are simultaneously induced by gamma rays.

    Original languageEnglish
    Article number533
    JournalPolymers
    Volume9
    Issue number10
    DOIs
    Publication statusPublished - 2017 Oct 20

    Keywords

    • Conductivity
    • Dielectric property
    • Gamma irradiation
    • SiR
    • Trap distribution

    ASJC Scopus subject areas

    • Chemistry(all)
    • Polymers and Plastics

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