Comparison of two accelerated Nafion™ degradation experiments

Aspects of fatigue failure mechanisms in polymer fuel cell membranes

“…For example, decomposition of the mem brane, as well as the formation of pinholes due to chemical degradation (e.g., open circuit voltage decay tests), can cause degradation of the mechanical properties. 6,[24][25][26] Thus, degradation of the mechanical properties during cy cling might increase the chance of crack propagation, hence causing the parameters A and B to become functions of time and making the failure criterion nonlinear and coupled. Also, thresholds for the onset of crazing (e.g., B) have been shown to decrease with increasing temperature and in the presence of water for other polymers 57,58 and are likely to do so for PFSA as well.…”

“…17,26,27 Lastly, even though chemical degradation is primarily responsible for the decomposition of the mem brane and material losses, the stresses contribute to the failure mechanisms by propagating cracks or by forming crazes, and therefore opening new surfaces for degradation. For example, a recent study reported, using a gas-phase ex situ chemical degradation test, that the degradation rate increased when the membrane was under tension providing evidence for combined chemical-mechanical effects.…”

Effect of Mechanical Compression on Chemical Degradation of Nafion Membranes

“…These latter stressors originate from the deformation of the membrane due to cell assembly (constraint) and subsequent operational stresses driven by the hydration/dehydration of the constrained membrane. [1][2][3][4][5][6][7] To understand the impact of various stressors, accelerated stress tests (ASTs) are typically conducted with the aim of enhancing a single failure mode, 1,2,8 with Fenton's tests accelerating chemical degradation 7,9-14 and relative-humidity (RH) cycling used for mechanical degradation. [1][2][3]6,8,15 However, failure mechanisms in operando are controlled by combination of chemical and mechanical stressors, which makes understanding any synergistic chemical/mechanical interactions of great importance.…”

“…1,[9][10][11][12][13][14]16 Fenton's Test is commonly employed to study the chemical-decomposition behavior of a membrane by monitoring the release of fluoride ions from the PFSA membrane's fluorocarbon chains. 1,7,[9][10][11][12][13][14] While it is known that chemical degradation changes the membrane's mechanical and other properties, 7,17,18 it is unknown as to whether concurrent mechanical and chemical stressors act independently or in concert to alter membrane degradation rates. Such combined stresses are expected to occur under actual operation due to simultaneous load and humidity changes.…”

Polymer and Hybrid Materials: Electrochemistry and Applications

“…As a result, many such studies have been conducted under open-circuit conditions [10][11][12][13]. In order to minimize the testing time and resources involved, simulated conduction tests may offer an alternative approach, and are typically based on the use of H 2 O 2 solution [14], Fentons reagent [15], and the simulation of cell environments [16][17][18]. As an example, Liu et al [19] reported the details of an electrochemical technique that used a thin Pt wire as the working electrode, for determining H 2 O 2 concentrations within the PEM of operating fuel cells.…”