| Numéro |
J. Phys. IV France
Volume 05, Numéro C1, Janvier 1995
Europhysics Industrial Workshop EIW-12Industrial Applications of Positron Annihilation |
|
|---|---|---|
| Page(s) | C1-199 - C1-203 | |
| DOI | https://doi.org/10.1051/jp4:1995123 | |
Industrial Applications of Positron Annihilation
J. Phys. IV France 05 (1995) C1-199-C1-203
DOI: 10.1051/jp4:1995123
Free Volumes in Polystyrene Probed by Positron Annihilation
A. Uedono1, T. Kawano2, L. Wei1, S. Tanigawa1, M. Ban3 and M. Kyoto31 Institute of Materials Science, University of Tsukuba, Ibaraki 305, Japan
2 Radioisotope Center, University of Tsukuba, Tsukuba, Ibaraki 305, Japan
3 Analytical Characterization Center, R&D Group, Sumitomo Electric Industries Ltd., 1 Taya-cho, Sakae-ku, Yokohama 244, Japan
Abstract
Polystyrene specimens with different molecular weights were characterized by the positron annihilation technique. Lifetime spectra of positrons were measured in the temperature range between room temperature and ~150 °C. The observed lifetime spectra were resolved into three components, where the longest lifetime, τ3, was associated with pick-off annihilation of orthopositronium (o-Ps) trapped by free-volumes. Above the glass transition temperature (Tg), the temperature coefficient of τ3 was found to be about 4 times larger than that below Tg, wile no drastic change in the intensity corresponding to the annihilation of o-Ps was observed at Tg. These facts suggest that the glass transition mainly affects the expansion rate of the free volumes in polystyrene specimens.
© EDP Sciences 1995