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Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation
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...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418885/ https://www.ncbi.nlm.nih.gov/pubmed/30965834 http://dx.doi.org/10.3390/polym9100533 |
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author | Min, Daomin Yan, Chenyu Huang, Yin Li, Shengtao Ohki, Yoshimichi |
author_facet | Min, Daomin Yan, Chenyu Huang, Yin Li, Shengtao Ohki, Yoshimichi |
author_sort | Min, Daomin |
collection | PubMed |
description | 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 coefficient 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 coefficient 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. |
format | Online Article Text |
id | pubmed-6418885 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-64188852019-04-02 Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation Min, Daomin Yan, Chenyu Huang, Yin Li, Shengtao Ohki, Yoshimichi Polymers (Basel) Article 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 coefficient 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 coefficient 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. MDPI 2017-10-20 /pmc/articles/PMC6418885/ /pubmed/30965834 http://dx.doi.org/10.3390/polym9100533 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Min, Daomin Yan, Chenyu Huang, Yin Li, Shengtao Ohki, Yoshimichi Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title | Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title_full | Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title_fullStr | Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title_full_unstemmed | Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title_short | Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation |
title_sort | dielectric and carrier transport properties of silicone rubber degraded by gamma irradiation |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418885/ https://www.ncbi.nlm.nih.gov/pubmed/30965834 http://dx.doi.org/10.3390/polym9100533 |
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