Proton exchange membrane mechanical properties

Phadnis, S., Patri, M., Chandrasekhar, L. and Deb, P. C. 2005. Proton-exchange membranes via the grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer by a preirradiation technique. III. Thermal and mechanical properties of the membranes and their sulfonated derivatives. Journal of Applied Polymer Science 97 1418-1425. 

The required properties of solid polymer electrolyte membranes may be divided into interfacial and bulk properties [9]. As described above, the interfacial characteristics of these membrane materials are important for the optimum formation of the three-phase boundary. Hence, flow properties, gas solubility, wetting of carbon supported catalyst surfaces by the polymer, etc. are of paramount importance. The bulk properties concern proton conductivity, gas separation, and mechanical properties. This whole ensemble of properties has to be considered and balanced in the development of novel proton-exchange membranes for fuel cell application. 

Esteban A. Franceschini was bom in Cordoba, Argentina, in 1985. Ph.D. in Chemistry at the University of Buenos Aires (2012), and postdoctoral fellow at the Nanomaterials group in the National Commission of Atomic Energy. He is also Assistant Researcher of the National Council of Scientific and Technological Research (CONICET). He has published eight articles in international journals and has presented several works in national and international meetings. His research areas include the mechanical, thermodynamics, and electrochemical properties of proton exchange membranes, and alternative catalysts for PEM fuel cells. 

Therefore, an ideal proton exchange membrane must possess high proton conductivity but low electronic conductivity, high mechanical strength and size stability, and good chemical, electrochemical, and thermal stabihty. Among aU these characteristics, the bottleneck property is high proton conductivity. 

Carbon nanotubes (CNTs) have been added to a polymeric matrix to improve their mechanical and other properties [69]. The use of CNTs in PEM must be carried out with caution because the well-known high electrical conductivity may cause short circuiting in proton exchange membrane fuel cells. The jt-n interaction between PBI and the side walls of CNT makes these two different materials compatible. Despite CNT-PBI composite membranes have shown enhancement in mechanical strength, the proton conductivity resulted in some cases compromised [70, 71]. Hence, different authors functionalized the CNTS in order to increase both the proton conductivity and the mechanical properties for hydrogen fed PBI-based HT-PEMFC [72, 73]. In this context,... 

Tseng C-Y, Ye Y-S, Cheng M-Y et al (2011) Sulfonated polyimide proton exchange membranes with graphene oxide show improved proton conductivity, methanol crossover impedance, and mechanical properties. Adv Energy Mater 1 1220-1224... 

This chapter is a review focussed on the development of ionomers based on aromatic polysulfones for their application as Polymer Electrolyte Membrane (PEM) in Proton Exchange Membrane Fuel Cells (PEMFC) or in Direct Methanol Fuel Cells (DMFC). Different types of synthesis routes have been discussed in this chapter in order to obtain ionomers based on polysulfones with variation in structural designs. Special attention is given to the impact of the structural design of the ionomer on various properties such as membrane morphology, thermo-mechanical stability and protonic conductivity of the membranes for their utilization as PEMs. 

Numerous works by other authors and our own research group describe the syntheses of new proton exchange membranes based on hydrocarbon polymers. The characteristics of these new materials, which determine their potential applications, are discussed in detail. A review of electrochemical properties, water uptake, and thermal stability makes possible a comprehensive understanding of the proton conduction mechanism and physical state of absorbed water in these systems. 

It is essential for proton exchange membranes to retain their mechanical strength under humidified conditions in the light of membrane electrode assembly (MEA) to be used in fuel cells. In general, electrolyte membranes are moisture-sensitive materials. Obviously, under wet conditions, the mechanical properties of the electrolyte membranes are lowered compared with those measured under dry conditions. Figure 6.18 shows tensile strength vs. strain for dry and wet SPTES-50 membrane as well as for dry and wet Nafion-117 membrane. 

As the proton-exchange membrane in the PEEC has to provide a physicochemical and mechanical fnnctionality, the following membrane material properties are of primary importance ... 

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