Accession Number : ADA624943


Title :   Water Uptake Profile In a Model Ion-Exchange Membrane: Conditions For Water-Rich Channels


Descriptive Note : Doctoral thesis


Corporate Author : COLORADO SCHOOL OF MINES GOLDEN


Personal Author(s) : Herbst, Daniel C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a624943.pdf


Report Date : Dec 2014


Pagination or Media Count : 83


Abstract : Ionic conductivity in a polymeric fuel cell requires water uptake. Previous theoretical studies of water uptake used idealized parameters. We report a parameter-free prediction of the water-swelling behavior of a model fuel cell membrane. The model polymers, poly(methyl- butylene)-block-poly(vinylbenzyl-trimethylamine) (PMB-b- PVBTMA), form lamellar do- mains that absorb water in humid air. We use the Scheutjens-Fleer methodology to predict the resulting change in lamellar structure and compare with x-ray scattering. The results suggest locally uniform water distributions. However, under conditions where a PVBTMA and water mixture phase-separate, the two phases arrange into stripes with a dilute stripe sandwiched between two concentrated stripes. A small amount of water enhances conductivity most when it is partitioned into such channels, improving fuel-cell performance.


Descriptors :   *FUEL CELLS , *ION EXCHANGE , *WATER , *X RAY SCATTERING , ABSORPTION , ALKALINITY , CATHODES , CONDUCTIVITY , DIFFERENTIAL EQUATIONS , DILUTION , ELECTROCHEMISTRY , ELECTROLYTES , ENERGY DENSITY , MATHEMATICAL PREDICTION , MEMBRANES , METHYL RADICALS , OXIDATION , PERFORMANCE(ENGINEERING) , POLYMERS , POTASSIUM COMPOUNDS , SYNTHESIS(CHEMISTRY) , THESES , TRANSPORT


Subject Categories : Physical Chemistry
      Electrochemical Energy Storage


Distribution Statement : APPROVED FOR PUBLIC RELEASE