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

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 mu N/s, longer than 20 s and 100 mu N for dry Nafion 117. POLYM. ENG. SCI., 58:2071-2077, 2018. (c) 2018 Society of Plastics Engineers