Influence of Compressive Stress on the Water Content of Perfluorosulphonated Membranes: A μ-Raman Study

The effect of compressive stress on the local water content of Nafion NRE 212 and Aquivion E79 membranes is studied by confocal μ‐Raman spectroscopy using a specific tightening device. This device aims to mimic the geometry of the bipolar plate flow field of actual fuel cells, i.e. the sequence of channels and ribs. The membrane water content decreases with increasing stress, under the ribs as well as in the channel. The higher the initial water content, the larger the water content decreases with mechanical stress. The extent of water loss depends on the position of the membrane in the device, the applied stress and the hydration history of the membrane.