Book/Dissertation / PhD Thesis

FZJ-2018-05706

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Adhäsionsverhalten von wässrigen Nafion-Lösungen an dispersen Phasengrenzen

Schulz, A. (Corresponding author)FZJ*

2018
Forschungszentrum Jülich GmbH Zentralbibliothek, Velag Jülich
ISBN: 978-3-95806-354-9

Please use a persistent id in citations: http://hdl.handle.net/2128/19900  urn:nbn:de:0001-2018120617

Abstract: A key component of polymer electrolyte membrane fuel cells and electrolyzers is the membrane electrode assembly (MEA). One component of the MEA is the porous catalyst layer. To this date it remains a challenge to produce the catalyst coating in a controlled manufacturing process chain. In this study, the adhesion behavior of water/alcohol based Nafion solutions at different dispersive phase boundaries will be investigated. This behavior is an important key to understanding and controlling the coating process in the MEA manufacturing process chain. In addition to studying the substrates PTFE, ETFE, polystyrene and paraffin, two concentration series (water/2-methyl-2-butanol and water/Nafion/2-methyl-2-butanol) are investigated in which only the alcohol component is varied. To analyze the adhesion behavior, the free surface energy of the substrates and the surface tension of the solutions are determined and the phase boundary behavior between substrate and solution is characterized. The methods used include the Wilhelmy-method, the bubble pressure tensiometer and the drop shape analysis (pendent drop and sessile drop). These methods examine the static and dynamic behavior of surface tension and contact angle. The free surface energies are determined according to Owens-Wendt. The results show that the solutions of water/2-methyl-2-butanol 10.2 wt% and water/Nafion 5.5 wt%/2-methyl-2-butanol 10.2 wt% cannot be distinguished by surface tension measurements. Furthermore, the contact angle between the two solutions on the same substrates is the same within the measurement uncertainty. When determining the receding angle it becomes clear that both solutions on paraffin show no permanent adhesion behavior. Due to the low surface energy of paraffin, this result is expected. Both solutions adhere to the substrate polystyrene, which can be explained by the high surface energy of polystyrene. On the substrates PTFE and ETFE, which have even lower surface energy than paraffin, water/2-methyl-2-butanol 10.2 wt% does not adhere; however, a permanent adhesion behavior of water/Nafion 5.5 wt%/2-methyl-2-butanol 10.2 wt% solution can be observed on PTFE and ETFE.This significant difference in adhesion behavior on PTFE and ETFE of two solutions with approximately the same surface tension is outstanding seeing as they both do not adhere to paraffin; adhesion on PTFE and ETFE must therefore involve substance-specific effects and cannot be explained by only considering surface tension and surface energy.

Note: RWTH Aachen, Diss., 2018

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Contributing Institute(s):

1. Elektrochemische Verfahrenstechnik (IEK-3)

Research Program(s):

1. 135 - Fuel Cells (POF3-135) (POF3-135)

Appears in the scientific report 2018

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Database coverage:
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