@misc{oai:repo.qst.go.jp:00072936,
 author = {岡, 壽崇 and 長澤, 尚胤 and 木野, 康志 and 関根, 勉 and 長澤 尚胤},
 month = {Sep},
 note = {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., The 10th International Conference of Modification, Degradation and Stabilization of Polymers (MoDeSt2018)},
 title = {DEGRADATION OF GAMMA-RAY IRRADIATED POLYETHYLENE FILMS STUDIED BY POSITRON ANNIHILATION},
 year = {2018}
}