J. Phys. IV France 03 (1993) C4-279-C4-281
Positron lifetime measurements in polyethylene under different conditionsG. BRAUER1, Th. DANIEL2, W. FAUST3, Z. MICHNO4 and H. SCHNEIDER3
1 Research Centre Rossendorf Inc., WIP Project, P.O. Box 510119, 01314 Dresden, Germany
2 Phys. Chem. Institut
3 Strahlenzentrum, Univ. Giessen, 35392 Giessen, Germany
4 Technical University Opole, Poland
Positron lifetime measurements were performed on polyethylene probes of different densities under various atmospheric conditions within a [MATH]-dose range from 0 kGy up to 1460 kGy. We present here experiments non destroying the sample. Four components could be resolved in each lifetime spectrum ; the components consist each of a lifetime [MATH] and an intensity I. In the dose range investigated the behaviour of the lifetime parameters of the longest lived ([MATH]) and the second long-lived ([MATH]) component, respectively, could be explained by the [MATH] recristallisation and the creation of hydroperoxides. The average free volume as a function of the dose may be calculated out of the lifetime of the fourth component ([MATH]).
© EDP Sciences 1993