positron irradiation effects in hdpe during pal measurement at room temperature
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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 - PowerPoint PPT PresentationTRANSCRIPT
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Positron Irradiation Effects in HDPE during PAL Measurement at room temperature
J. Kansy1 and M. Ziąbka2
1 Institute of Material Science, Silesian University, Bankowa 12, 40-008 Katowice, Poland
2 Faculty of Materials Science and Ceramic, University of Science and Technology, A. Mickiewicza 30, 30-059 Krakow, Poland
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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 positron source irradiation
Positron irradiation effect in polymers
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. Peng at al. phys.stat.sol. (a) 155, 299 (1996)
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Positron irradiation effects in polymers of various crystallinity
T. Suzuki at al. Radiat. Phys. Chem. 45, 657 (1995)
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Positron irradiation effect in non-polar and polar polymers
Z.L. Peng at al. phys.stat.sol. (a) 155, 299 (1996)
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Positron irradiation effect in HDPE (0.960g/cm3) - present work
Time dependence of the o-Ps intensity I3 in 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
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Model of spectrum J Kansy and T Suzuki, Radiation Physics and Chemistry 76 (2007) 759–765
Delayed Formation of Ps (DFP)
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Analysis with „LT Polymers” software
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Delayed Formation of Positronium – Results for HDPE
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- correlation
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- correlation in HDPE and LDPE at low temperatures (30 K)
J Kansy and T Suzuki, Radiation Physics and Chemistry 76 (2007) 759–765
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- correlation in ethylene-methyl methacrylate copolymers (EMMA) at low temperature (30 K)
J Kansy and T Suzuki, ACTA PHYSICA POLONICA A 110 (2006) , 593
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Modified DFP model
e+ trapping rate into free volume ()
e+ te+ ortho p
400 ps 956 ps 2.43 ns 0.511
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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
Conclusions
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Address of Website with programs LT9, LT10, LT Polymer and others:
www.prac.us.edu.pl/~kansy
Thank you for your attention