Positron annihilation studies of the effect of gamma irradiation dose in polymers
AuthorAl-Qaradawi, I. Y.
Britton, D. T.
Abdel-Hady, E. E.
Abdulmalik, D. A.
Al-Shobaki, M. A.
MetadataShow full item record
Positron annihilation lifetime (PAL) technique has been applied to study the effect of gamma irradiation dose on the structure of low-density polyethylene and polystyrene. The positron annihilation lifetime measurements were performed with a conventional fast-fast coincidence system. Gamma irradiation was carried out at room temperature with a 60Co gamma source up to a dose of 1000kGy. The delayed lifetime spectra of irradiated and unirradiated samples were decomposed into three lifetime components. The lifetime parameters give indication of the free-volume size and concentration. It was found that the crosslinking efficiency in the polymer increases significantly with increasing irradiation dose. This appears as a decrease in the intensity of the long-lived positron lifetime components attributed to ortho-positronium formation. Measurements of the Doppler broadening energy spectra of the low-density polyethylene (LDPE) samples have also been performed using a variable mono-energetic positron beam. The trend of the Doppler broadening lineshape S-parameter as a function of the radiation dose supports the lifetime results. © 2003 Elsevier Ltd. All rights reserved.
- Mathematics, Statistics & Physics [606 items ]