量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Degradation of gamma-ray irradiated polyethylene films were studied by positron annihilation lifetime spectroscopy (PALS) using 22Na positron source. Application of PALS relies on the fact that some of the positrons injected into a polymer combine with an electron to form the hydrogen-like bound state, positronium. In a polymer, spin-parallel ortho-positronium (o-Ps) annihilates by pick-off annihilation in
a free volume with one of the surrounding electrons and the lifetime of o-Ps increases with increasing
hole size, so we can estimate the free volume size from the lifetime of o-Ps.
The obtained results demonstrated that PALS can be useful as an indicator of the structural change induced by irradiation and long-term storage in HDPE. In the presentation, results for gamma-ray were compared with the results for electron-beam polyethylene to discuss the difference of the radiation.
会議概要（会議名, 開催地, 会期, 主催者等）
The 10th International Conference of Modification, Degradation and Stabilization of Polymers (MoDeSt2018)
DEGRADATION OF GAMMA-RAY IRRADIATED POLYETHYLENE FILMS STUDIED BY POSITRON ANNIHILATION
