Study of azoles as bifunctional additives for proton exchange membranes melt-processing from LSC and SSC perfluorosulfonic acid ionomers

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DOIResolve DOI: http://doi.org/10.1149/06403.0377ecst
AuthorSearch for:
TypeArticle
Proceedings titlePolymer Electrolyte Fuel Cells 14 (PEFC 14)
Series titleECS Transactions; no. 64(3)
Conference2014 ECS and SMEQ Joint International Meeting, October 5-9, 2014, Cancun, Mexico
ISSN1938-6737
1938-5862
Pages377388; # of pages: 12
AbstractThis work investigates the potential use of azoles as bifunctional additives for proton exchange membranes (PEM) manufacturing through direct melt-processing of acidic ionomers. The development of high-volume manufacturing processes to prototype PEM fuel cell components with a reduced number of steps is vital to reduce system cost and complexity, and to meet the demands of high volume production and durability requirements especially for automotive applications. The strong ionic associations in ionomers act generally as physical cross-links, increasing by several orders of magnitude both melt-viscosities and relaxation times, resulting in ionomeric materials that are very difficult to melt-process with high shear rate processes such as melt-casting or melt-blowing. The strength of the ionic interactions in ionomers, and hence their physical and mechanical properties, depends on the acidity of the pendent anion. Polymers modified with the stronger acid, such as sulfonic acid (pKa~1), exhibit more dramatic changes in thermal, viscoelastic, and rheological properties than those modified with the weaker carboxylic acid (pKa~4-5). However, most ionomers may be melt-processed in very low shear rate operations such as compression-molding, which reveals that these ionic associations are not permanent cross-links and can be reversibly disrupted under suitable conditions. The approach investigated is based on the use of selected bi-functional additives that act as a SO3H groups protec­tion and a melt-processing aid.[1] The additives selected are highly polar additives with relatively high boiling points that are expected to interact with the ion-rich aggregates that compose the nanophase separation in ionomers and act as plasticizers which expectantly improve the viscoelastic behavior during melt processing. Additives from the azole family, imidazole, 1,2,4-triazole and benzimidazole have been investigated as potential bifunctional additives. This presentation, will discuss the results obtained with four commercial PFSA ionomers Nafion® DE-2020 and NR-40 with long side chain (LSC), and Aquivion® D83-24B and D79-20BS with short side chain (SSC).
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; Automotive and Surface Transportation
Peer reviewedYes
NPARC number21272407
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Record identifierb16b8942-c651-4991-92ff-6dad75bf5dbb
Record created2014-11-25
Record modified2016-05-25
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