Comparison between poly(ethylene naphthalate) and poly(ethylene terephthalate) in terms of gamma-ray irradiation on their dielectric properties

The effects of gamma-rays on the complex permittivity (ϵr' and ϵr'') and electrical conductivity were compared between poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET). Although both ϵ'r and ϵ''r increase in PET with an increase in the total dose of gamma irradiation, such increases are hardly observed in PEN. The conductivity is always smaller in PEN than in PET. Therefore, it has been confirmed that charge transport is less activated by gamma irradiation in PEN than in PET. Together with experimental results obtained by ultraviolet-visible absorption spectroscopy and thermogravimetric analysis, it can be concluded that PEN has a superior anti-gamma-ray dielectric property to PET.