Реологические эффекты при набухании полимерных мембран в воде

Abstract

The study focuses on rheological effects which appear during swelling of the Nafion proton-exchange membrane in cuvettes of different thicknesses, and explains the effects by the appearance of the so-called excluded zone near the membrane surface. The excluded zone is the polymer fibers of the Nafion membrane, deployed towards bulk water. The depth of fiber penetration into the volume or the size of the excluded zone depends on the deuterium content in the water. It should be noted that in the process of swelling of the Nafion membrane plate in water it is structurally rearranged, which leads to a transition from a hydrophobic state to a hydrophilic one. By means of experimental methods based on Fourier transform infrared spectrophotometry, the study shows that the swelling of the Nafion membrane plate, which is initially hydrophobic, in ordinary water (deuterium content is 157 ppm) and in deuterium-depleted water (deuterium content is 1 ppm) in a cuvette of limited volume occurs differently. Small changes in the deuterium content in water turned out to lead to significant differences in the dynamics of swelling of the polymer membrane. For a 175-micron-thick Nafion membrane plate, this effect is most evident when the distance between the cuvette windows is L = 200 microns