Topic
Nafion
About: Nafion is a research topic. Over the lifetime, 9110 publications have been published within this topic receiving 320865 citations.
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TL;DR: In this paper, a new hydrophobic-hydrophilic multiblock copolymer was successfully synthesized based on the careful coupling of a fluorine terminated poly(arylene ether ketone) (6FK) hydrophilic oligomer and a phenoxide terminated disulfonated poly sulfone (BPSH), and the comparison of the 13 C NMR spectrum with that of the random copolymers showed that the transetherification side reaction was minimized in this synthesis.
90 citations
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TL;DR: Sorption kinetics was found to be a function of flow rate, where mass transfer resistance at the vapor/polymer interface was significant at low flow rates but was insignificant at high flow rates.
Abstract: Hydrogen fuel cells are attractive alternative power sources for applications such as transportation; however, fuel cell performance is a strong function of water equilibrium content and water sorption and desorption kinetics in polymer electrolyte membranes (e.g., Nafion). Although similar water sorption isotherms for Nafion have been reproduced in many laboratories, reported diffusion coefficients of water in Nafion vary by 4 orders of magnitude. In this study, sorption and desorption dynamics of water vapor in Nafion were measured as a function of water vapor activity and flow rate using time-resolved Fourier transform infrared−attenuated total reflectance (FTIR-ATR) spectroscopy. Both integral and differential experiments were performed, where integral experiments consisted of increasing the vapor activity from 0% RH to one of five values (22, 43, 56, 80, or 100% RH), while in differential experiments the activity was sequentially increased in smaller steps from 0 to 22 to 43 to 56 to 80 to 100% RH. F...
90 citations
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TL;DR: In this paper, a blend membrane consisting of sulfonated poly(ether sulfone) (SPES) and sulfonate poly (ether ether ketone), called SPES/SPEEK, for vanadium redox flow battery (VRB) was fabricated and characterized.
90 citations
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TL;DR: In this article, the influence of current density on the charge/discharge characteristics, coulombic and energy efficiency, capacity fade, operating temperature and pressure drop in the flow circuit was discussed and correlated to the Nafion ® membrane thickness.
90 citations
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TL;DR: In this article, the dynamics of water in Nafion was investigated at both low and high humidities with time-resolved Fourier transform infrared−attenuated total reflectance (FTIR−ATR) spectroscopy; a technique that provides a molecular fingerprint of both the diffusant and the polymer simultaneously in real time.
Abstract: Understanding the dynamics of water in solid-state polymer electrolytes (e.g., Nafion) is important for a variety of applications ranging from membrane-based water purification to hydrogen fuel cells. In this study, the dynamics of water in Nafion was investigated at both low and high humidities with time-resolved Fourier transform infrared−attenuated total reflectance (FTIR−ATR) spectroscopy; a technique that provides a molecular fingerprint of both the diffusant and the polymer simultaneously in real time. At low humidities (0−22% RH), an extended initial time lag resulted in non-Fickian behavior, where dynamic infrared data provided evidence for a reaction between water and sulfonic acid. A diffusion−reaction model was developed and predicted this anomalous behavior, where the time lag was a function of water content. At high humidities (0−100% RH), a slow approach to steady state resulted in non-Fickian behavior, where dynamic infrared data provided evidence of water-induced relaxation in the polymer ...
90 citations