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Positron Irradiation Effects in HDPE during PAL Measurement at room temperature

Positron Irradiation Effects in HDPE during PAL Measurement at room temperature. J. Kansy 1 and M. Ziąbka 2 1 Institute of Material Science, Silesian University, Bankowa 12, 40-008 Katowice, Poland

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Positron Irradiation Effects in HDPE during PAL Measurement at room temperature

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  1. Positron Irradiation Effects in HDPE during PAL Measurement at room temperature J. Kansy1and M. Ziąbka2 1Institute of Material Science, Silesian University, Bankowa 12, 40-008 Katowice, Poland 2Faculty of Materials Science and Ceramic, University of Science and Technology, A. Mickiewicza 30, 30-059 Krakow, Poland

  2. Positron irradiation effect in polymers • Positrons emitted from 22Na induce irradiation damage in polymer - intensity of the longest-lived component I3 decreases gradually with the measurement time. • Small dose of irradiation deposing (~ 1kGy e+ and 102 Gy)– large effect on I3 = I3 (t) (t ~ 10 h) • 3 not effected by positronsourceirradiation M. Welander and F.H.J. Maurer. Matter. Sci. Forum. 105/110, 1811 (1992) T. Suzuki at al. Radiat. Phys. Chem. 45, 657 (1995) Z.L. Pengatal. phys.stat.sol. (a) 155, 299 (1996)

  3. Positron irradiation effects in polymers of various crystallinity T. Suzuki at al. Radiat. Phys. Chem. 45, 657 (1995)

  4. Positron irradiation effect in non-polar andpolarpolymers Z.L. Pengat al. phys.stat.sol. (a) 155, 299 (1996)

  5. Positron irradiation effect in HDPE (0.960g/cm3)- present work Time dependence of the o-Ps intensity I3in HDPE (crystallinity 57%). Data collected at 300 K. The measurement was discontinued (sample separated from positron source) at point a) for 10 days, at point b) – for 2 days, and at point c) – for 17 days – process partially recoverable

  6. Model of spectrum J Kansy and T Suzuki, Radiation Physics and Chemistry 76 (2007) 759–765 Delayed Formation of Ps (DFP)

  7. Analysis with „LT Polymers” software

  8. Delayed Formation of Positronium – Results for HDPE

  9.  -  correlation

  10.  -  correlation in HDPE and LDPE at low temperatures (30 K) J Kansy and T Suzuki, Radiation Physics and Chemistry 76 (2007) 759–765

  11.  - correlation in ethylene-methyl methacrylate copolymers (EMMA) at low temperature (30 K) J Kansy and T Suzuki, ACTA PHYSICA POLONICA A110 (2006) , 593

  12. Modified DFP model e+trappingrateintofreevolume ()

  13. Conclusions • The DFP model well described the HDPE lifetime spectra collected at room temperature • The positronium formation seems to be connected with positron trapping in free volume at vicinity of a negative charge • The decrease in efficiency of Ps formation with the time of measurement (=time of sample irradiation) is due to scavenging of quasi-free electrons by free radicals induced by the source irradiation

  14. Thank you for your attention Address of Website with programs LT9, LT10, LT Polymer and others: www.prac.us.edu.pl/~kansy

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