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Electric resistance in a Nafion® membrane exposed to air after a step change in the relative humidity

1995; Elsevier BV; Volume: 385; Issue: 2 Linguagem: Inglês

10.1016/0022-0728(95)03767-b

1873-2569

František Opekar, Daniel Svozil,

Advanced Battery Technologies Research

Solid polymer electrolytes in the form of membranes are often used in industrial electrolysers, fuel cells and solid-state chemical sensors. Perfluorosulphonic membranes known under the name Nation ® (DuPont) are the most common. The physico-chemical properties of solid polymer electrolytes are strongly dependent on the amount of water contained within the membrane [1]. The relationship between the water content in the membrane and the electric resistance or conductivity of the membrane is usually obtained from a measurement of the resistance of a membrane sample containing a defined amount of water, under conditions ensuring that Nafion ® does not exchange water with the environment for the time of measurement. The resultant membrane resistance values then correspond to certain equilibrium water contents [2,3]. The present paper follows the changes in the resistance of a Nation ® membrane during the process in which one equilibrium water content changes into another owing to exchange of water between Nafion ® and ambient air of a certain relative humidity (RH). The air R H is changed stepwise and the time dependence of the Nation ® resistance is monitored. The conductivity electrodes formed directly on the Nation ® membrane surface make possible continuous resistance monitoring.