Effect of Hygrothermal Ageing on PFSA Ionomers' Structure/Property Relationship

Effect of Hygrothermal Ageing on PFSA Ionomers' Structure/Property Relationship

TitleEffect of Hygrothermal Ageing on PFSA Ionomers' Structure/Property Relationship
Publication TypeJournal Article
Year of Publication2015
AuthorsShouwen Shi, Thomas J Dursch, Rodney L Borup, Adam Z Weber, Ahmet Kusoglu
JournalECS Transactions
Volume69
Issue17
Pagination1017 - 1025
Date Published09/2015
ISSN1938-6737
Abstract

Perfluorosulfonic-acid (PFSA) membranes are frequently subjected to high humidity and temperature cycles during fuel-cell operation. It is of great interest to understand how the properties of the membrane change with ageing conditions and time. In this study, we investigate how the properties of as-received and pretreated Nafion membranes change after exposure to hygrothermal ageing, including the chemical structure, mechanical properties, water uptake, ionic conductivity, and morphology. Our findings demonstrate that anhydrides form during ageing via a condensation reaction, which results in chemical crosslinks that impair the membrane functionalities by reducing water uptake and conductivity and increasing the storage modulus and α relaxation temperature. In addition, a membrane aged in a 75% relative humidity environment exhibits more dramatic changes compared to that aged in 100% conditions. It is also shown that the impact of ageing can be recovered through a post-treatment by boiling the membrane in strong acid.

DOI10.1149/06917.1017ecst
Short TitleECS Transactions