Free Volume in Polycarbonate Studied by Positron Annihilation. Temperature and Irradiation Effect on Positronium Formation.
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Accession number;01A0231205
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| Title;Free Volume in Polycarbonate Studied by Positron Annihilation. Temperature and Irradiation Effect on Positronium Formation. |
| Author;
CHEN Z Q
(Univ. Tsukuba, Ibaraki, Jpn)
SUZUKI T
(Kek, Ibaraki, Jpn)
KONDO K
(Kek, Ibaraki, Jpn)
HAMADA E
(Ibaraki Prefectural Univ. Health Sci., Ibaraki, Jpn)
UEDONO A
(Univ. Tsukuba, Ibaraki, Jpn)
TANIGAWA S
(Univ. Tsukuba, Ibaraki, Jpn)
ITO Y
(Univ. Tokyo, Ibaraki, Jpn)
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Journal Title;Abstracts of Papers. Symposium on Radiochemistry
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Journal Code:F0139B
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ISSN:1345-2762
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VOL.44th;NO.;PAGE.48(2000)
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| Figure&Table&Reference; |
| Pub. Country;Japan |
| Language;English |
| Abstract;In this paper, we studied the free volume properties in polycarbonate by positron annihilation lifetime spectroscopy (PALS) as a function of temperature and elasped time. Free radicals and trapped electrons were introduced when the sample was exposed to positron source irradiation at room temperature and low temperature, respectively. O-Ps lifetime was not affected by irradiation, but free radicals act as a scavenger of electrons and prohibit the formation of positronium, while the trapped electrons enhance the Ps formation. By measuring the lifetime spectra in the temperature range from 20 .DEG.C. to 220 .DEG.C., and from 30K to 375K, we observed that the glass transition temperature was about 140 .DEG.C.. The methyl group rotation was known to start at about 100K, and caused the electrons to get detrapped from the free volumes. Another transition, the brittle-ductile transition, was also observed, which occurred at about 230K. (author abst.) |
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