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Study of free volumes in Nafion using positronium
Košinová, Lucie ; Čížek, Jakub (advisor) ; Vlach, Martin (referee)
Title: Study of free volumes in Nafion using positronium Author: Lucie Košinová Department: Department of Low-Temperature Physics Supervisor: doc. Mgr. Jakub Čížek, Ph.D., Department of Low-Temperature Physics Abstract: The object of this thesis is investigation of the absorption of water in Nafion and the influence of temperature on the absorption and desorption kinetics. Study of the absorption and desorption of water was carried out either measurement of changes in the macroscopic physical properties of Nafion (weighing, differential scanning calorimetry) either by microscopic characterization of the size distribution of free volume that arises as a consequence of an imperfect arrangement of polymer chains. For this purpose I used a non- destructive method used positron annihilation spectroscopy, which is currently the only technique capable of determination of the size distribution of free volumes having the free volume distribution by size of a few Å. The development of the size distribution and the concentration free volumes in the sample were determined on the based on the measurement of lifetime spectra of positrons annihilating in the sample of Nafion. The results obtained in this thesis can be further used in research of Nafion, which is widely used as a semipermeable membrane during industrial...
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Study of free volumes in Nafion using positronium
Košinová, Lucie ; Čížek, Jakub (advisor) ; Vlach, Martin (referee)
Title: Study of free volumes in Nafion using positronium Author: Lucie Košinová Department: Department of Low-Temperature Physics Supervisor: doc. Mgr. Jakub Čížek, Ph.D., Department of Low-Temperature Physics Abstract: The object of this thesis is investigation of the absorption of water in Nafion and the influence of temperature on the absorption and desorption kinetics. Study of the absorption and desorption of water was carried out either measurement of changes in the macroscopic physical properties of Nafion (weighing, differential scanning calorimetry) either by microscopic characterization of the size distribution of free volume that arises as a consequence of an imperfect arrangement of polymer chains. For this purpose I used a non- destructive method used positron annihilation spectroscopy, which is currently the only technique capable of determination of the size distribution of free volumes having the free volume distribution by size of a few Å. The development of the size distribution and the concentration free volumes in the sample were determined on the based on the measurement of lifetime spectra of positrons annihilating in the sample of Nafion. The results obtained in this thesis can be further used in research of Nafion, which is widely used as a semipermeable membrane during industrial...
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Influence of Organic Electrolytes Presence on Swelling of Nafion Membrane in Methanol-Water Mixtures
Randová, A. ; Hovorka, Š. ; Izák, Pavel ; Bartovská, L.
The anisotropic swelling of Nafion 112 foil in methanol - water - inorganic salt was examined. Our results show that even small addition of inorganic salt into methanol - water mixture affects kinetics as well as the swelling equilibrium. The effect of inorganic salts LiCl, NaCl, KCl, CsCl, CaCl2, CdCl2, K2CO3, KNO3, NH4Cl, and AgNO3 was studied. Swelling kinetics of Nafion in ternary mixtures including salt show maximum suggesting that effect of methanol-water is faster but effect of inorganic salt is stronger. Theexperimental data, presented in this work allow us to assume that swelling of Nafion decreases with increasing ionic radius of cation.
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