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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:07 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
Study of Nafion® membranes with repeated frost-defrost cycles (II)
Authors:
Paul-Emil MEREUTA
Affiliation:
University of Bucharest - Faculty of Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering
E-mail
pmereuta@yahoo.com, paul.mereuta@nipne.ro
Keywords:
polymer membranes, temperature, annihilation, lifetime, Peltier elements, frost defrost cycles
Abstract:
Nafion® membranes could be used to encapsulate radioactive waste. Our study, mainly targeted the way a Nafion® membrane can handle under extreme conditions; few frost-defrost cycles. Nafion® is a special polymer, having in its structure small functional ionic clusters (sulfonic or carboxylic) and thus it is part of a special category of polymers named ionomers. Also in its structure it has a hydrophobic region that is formed inside the lattice of the fluoro-carbonic polymer and the hydrophilic region contains ionic clusters. The linear size of such a volume of this morphologically separated phase are of trhe size of 30-50 Å. Our analysis wants to see if Nafion® can stand repeated cycles of frost-defrost and for this we have constructed a thermal box that uses two Peltier elements for cooling and heating, controlled through a display and a controller. The temperature range that the device can work is -20C - +30C; the minimum temperature can be reached in a few hours and then the sample can be heated gradually to room temperature (or as high as +30C). The method used to analyze the annihilation spectra was lifetime spectroscopy (PALS), in order to see the lifetime components of the polymer.
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