Effects of loading conditions on the nanoindentation creep behavior of nafion 117 membranes

Abstract

In this work, nanoindentation tests on Nafion 117 membranes are conducted under three different sets of loading conditions. The effects of loading/unloading rate, peak load and holding period on the mechanical responses of membranes are analyzed, respectively. The results demonstrate that the creep deformation as well as the modulus and hardness depend on these loading conditions, and appropriately fast loading/unloading rate, long enough holding time, relatively low peak load are essential to minimize the creep effect on the nanoindentation results. By analyzing the variation tendency of reduced modulus and hardness, the optimized loading/unloading rate, holding time and the peak load are >10 μN/s, longer than 20 s and 100 μN for dry Nafion 117. POLYM. ENG. SCI., 58:2071–2077, 2018. © 2018 Society of Plastics Engineers

Positron annihilation lifetime spectroscopic analysis of Nafion and graft‐type polymer electrolyte membranes for fuel cell application

“…In the case of hole volume distribution, we obtained an analogue distribution shape to that of the hole radius distribution. As depicted in Table 3, the hole sizes (0.379 nm and 0.232 nm 3 for Nafion-212 and 0.356 nm and 0.189 nm 3 for ETFE-PEM) are in accordance with those calculated by using the Tau-Eldrup equation (Table 2). Moreover, the FWHM values for Nafion-212 are quite analogous to those of ETFE-PEM, indicating a similar size distribution for both membranes.…”

“…[2][3][4] However, the membrane has exhibited several drawbacks, including high gas crossover, limited working temperature, high production costs, etc., which lead to the development of alternate membranes to replace Nafion. [2][3][4] Over the last 30 years, radiation-induced grafting and subsequent sulfonation have been a potential approach to prepare PEMs for fuel cell applications. [5] This approach allows us to create alternate membranes with promising physicochemical characteristics under controlled conditions of irradiation and grafting.…”

“…[2] Because of its exceptional chemical and physical stability and high proton conductivity in a wide range of relative humidity at mild operating temperatures, Nafion has been utilized as the most advanced PEM material. [2][3][4] However, the membrane has exhibited several drawbacks, including high gas crossover, limited working temperature, high production costs, etc., which lead to the development of alternate membranes to replace Nafion. [2][3][4] Over the last 30 years, radiation-induced grafting and subsequent sulfonation have been a potential approach to prepare PEMs for fuel cell applications.…”

Mechanical responses in the length direction and thickness direction of quaternary 1,4‐diazabicyclo‐[2.2.2]‐octane polysulfone alkaline anion‐exchange fuel‐cell membranes

“…Previously, we published articles focused on the durability of Nafion with the nanoindentation method. In this study, a quaternary 1,4‐diazabicyclo‐[2.2.2]‐octane polysulfone (QDPSU) alkaline anion‐exchange fuel‐cell membrane was synthesized.…”