@article{26186,
  keywords = {Model, Transportation, Polymer electrolytes, Electrolyte fuel-cells, In situ, Liquid water, Microchannel plate detectors, Nafion, Schroeders-paradox, X-ray scattering},
  author = {Daniel S Hussey and Dusan Spernjak and Adam Z Weber and Rangachary Mukundan and Joseph Fairweather and Eric L Brosha and John Davey and Jacob S Spendelow and David L Jacobson and Rodney L Borup},
  title = {Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography},
  abstract = {<p>The water sorption of proton-exchange membranes (PEMs) was measured <em>in situ</em> using high-resolution neutron imaging in small-scale fuel cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. An image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel cell and hydrogen-pump operation. The measured <em>in situ</em> water content of a restricted membrane at 80 degrees C is shown to agree with <em>ex situ</em> gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by <em>in situ</em> water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel cell operation, the measured water content indicates that the membrane is operating between the vapor-and liquid-equilibrated states.</p>},
  year = {2012},
  journal = {Journal of Applied Physics},
  volume = {112},
  pages = {104906},
  month = {11/2012},
  issn = {00218979},
  doi = {10.1063/1.4767118},
}