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Proton Exchange Membrane (proton + exchange_membrane)
Selected AbstractsHighly Fluorinated Comb-Shaped Copolymers as Proton Exchange Membranes (PEMs): Improving PEM Properties Through Rational Design,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2006B. Norsten Abstract A new class of comb-shaped polymers for use as a proton conducting membrane is presented. The polymer is designed to combine the beneficial physical, chemical, and structural attributes of fluorinated Nafion-like materials with higher-temperature, polyaromatic-based polymer backbones. The comb-shaped polymer unites a rigid, polyaromatic, hydrophobic backbone with lengthy hydrophilic polymer side chains; this combination affords direct control over the polymer nanostructure within the membrane and results in distinct microphase separation between the opposing domains. The microphase separation serves to compartmentalize water into the hydrophilic polymer side chain domains, resulting in effective membrane water management and excellent proton conductivities. [source] Low Water Swelling and High Proton Conducting Sulfonated Poly(arylene ether) with Pendant Sulfoalkyl Groups for Proton Exchange MembranesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2007Jinhui Pang Abstract Novel side-chain-type sulfonated poly(arylene ether) with pendant sulfoalkyl group copolymers (PSA-SPAE-6F) have been synthesized by direct copolymerization from a new sulfonated monomer, sodium 3-(4-(2,6-difluorobenzoyl)phenyl)propane-1-sulfonate. The sulfonate content could be easily controlled by adjusting the sulfonated and the unsulfonated monomer feed ratio. The obtained copolymers all show good thermal and mechanical properties. It should be noted that the most highly sulfonated copolymer, PSA-SPAE-6F90 with an ion exchange capacity of 1.30 mequiv,·,g,1, shows a proton conductivity of 0.11 S,·,cm,1 and a water swelling ratio of only 12.9% at 100,°C, which indicates its high proton conductivity and excellent dimensional stability in hot water. [source] ChemInform Abstract: One-Step Synthesized HPW/meso-Silica Inorganic Proton Exchange Membranes for Fuel Cells.CHEMINFORM, Issue 37 2010Haolin Tang Abstract A proton exchange membrane based on the self-assembled mesoporous H3PW12O40/SiO2 nanocomposite is synthesized from mixtures of H3PW12O40, Si(OEt)4, EtOH, and H2O (molar ratio of 0.007:1:11:2.5) in the presence of P123 surfactant (40 °C, 7 d). [source] Radiation Grafted Membranes for Polymer Electrolyte Fuel Cells,FUEL CELLS, Issue 3 2005L. Gubler Abstract The cost of polymer electrolyte fuel cell (PEFC) components is crucial to the commercial viability of the technology. Proton exchange membranes fabricated via the method of radiation grafting offer a cost-competitive option, because starting materials are inexpensive commodity products and the preparation procedure is based on established industrial processes. Radiation grafted membranes have been used with commercial success in membrane separation technology. This review focuses on the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis. The application in hydrogen and methanol fuelled cells is treated separately. Optimized styrene,/,crosslinker grafted and sulfonated membranes show performance comparable to perfluorinated membranes. Some properties, such as methanol permeability, can be tailored to be superior. Durability of several thousand hours at practical operating conditions has been demonstrated. Alternative styrene derived monomers with higher chemical stability offer the prospect of enhanced durability or higher operating temperature. [source] Miniature Biofuel Cells with Improved Stability Under Continuous OperationELECTROANALYSIS, Issue 19-20 2006Michael Abstract We have developed miniature biofuel cells (BFCs) with dimensions as small as 12×12×9,mm by adopting the design of stackable proton exchange membrane (PEM) fuel cells. The enzymatic anodes were constructed by using stabilized glucose oxidase (GOx) in the form of crosslinked enzyme clusters (CECs) on the surface of carbon nanotubes (CNTs). The combination of stabilized GOx and unbuffered fuel solution resulted in stabilized performance of miniature BFCs under continuous operation for more than 16 hours. This unprecedentedly high operational stability of miniature BFCs opens up new possibilities for many BFC applications. [source] A Porous Silicon-Based Ionomer-Free Membrane Electrode Assembly for Miniature Fuel CellsFUEL CELLS, Issue 5 2006T. Pichonat Abstract Previous work showed the pertinence of using grafted porous silicon as the proton exchange membrane for miniature fuel cells. One of the limitations was the membrane-electrodes assembly, which required an ionomer, in the current study a 5% Nafion®-117 solution, to ensure a proton-conducting link between the commercial carbon cloth electrodes and the membrane. Here, new developments for this fuel cell, with a totally Nafion®-free process, are reported. The Pt catalyst is sputtered and electrodeposited onto the surface of the proton conducting porous silicon membrane. The initial performance of this fuel cell is shown and demonstrates the validity of the technique. [source] A new parameter extraction method for accurate modeling of PEM fuel cellsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2009M. T. Outeiro Abstract In this paper, a new parameter extraction method for accurate modeling of proton exchange membrane (PEM) fuel cell systems is presented. The main difficulty in obtaining an accurate PEM fuel cell dynamical model is the lack of manufacturer information about the exact values of the parameters needed for the model. In order to obtain a realistic dynamic model of the PEM system, the electrochemical considerations of the system are incorporated into the model. Although many models have been reported in the literature, the parameter extraction issue has been neglected. However, model parameters must be precisely identified in order to obtain accurate simulation results. The main contribution of the present work is the application of the simulated annealing (SA) optimization algorithm as a method for identification of PEM fuel cell model parameter identification. The major advantage of SA is its ability to avoid becoming trapped in local minimum, as well as its flexibility and robustness. The parameter extraction and performance validation are carried out by comparing experimental and simulated results. The good agreement observed confirms the usefulness of the proposed extraction approach together with adopted PEM fuel cell model as an efficient tool to help design of power fuel cell power systems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Transport mechanisms and performance simulation of a PEM fuel cellINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2008Geng-Po Ren Abstract A three-dimensional, gas,liquid two-phase flow and transport model has been developed and utilized to simulate the multi-dimensional, multi-phase flow and transport phenomena in both the anode and cathode sides in a proton exchange membrane (PEM) fuel cell and the cell performance with different influencing operational and geometric parameters. The simulations are presented with an emphasis on the physical insight and fundamental understanding afforded by the detailed distributions of velocity vector, oxygen concentration, water vapor concentration, liquid water concentration, water content in the PEM, net water flux per proton flux, local current density, and overpotential. Cell performances with different influencing factors are also presented and discussed. The comparison of the model prediction and experimental data shows a good agreement. Copyright © 2007 John Wiley & Sons, Ltd. [source] Status and development of PEM fuel cell technologyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2008F. Barbir Abstract Fuel cells are an emerging technology with applications in transportation, stationary and portable power generation, with outputs ranging from mW to MW. The most promising and most widely researched, developed and demonstrated type of fuel cells is proton exchange membrane (PEM) fuel cell. State of the art in PEM fuel cell technology and challenges in their development and widespread applications are discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Exergetic performance analysis of a PEM fuel cellINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006M. Ay Abstract In this paper we investigate the effects of thermodynamic irreversibilities on the exergetic performance of proton exchange membrane (PEM) fuel cells as a function of cell operating temperature, pressures of anode and cathode, current density, and membrane thickness. The practical operating conditions are selected to be 3,5 atm for anode and cathode pressures, and 323,353 K for the cell temperatures, respectively. In addition, the membrane thicknesses are chosen as 0.016, 0.018 and 0.02 cm, respectively. Moreover, the current density range of the PEM fuel cell is selected to be 0.01,2.0 A cm,2. It is concluded that exergy efficiency of PEM fuel cell decreases with a rise in membrane thickness and current density, and increases with a rise of cell operating pressure and with a decrease of current density for the same membrane thickness. Thus, it can be said that, in order to increase the exergetic performance of PEM fuel cell, the lower membrane thickness, the lower current density and the higher cell operating pressure should be selected in case PEM fuel cell is operated at constant cell temperature. Copyright © 2005 John Wiley & Sons, Ltd. [source] Field and Laboratory Alcohol Detection With 2 Types of Transdermal DevicesALCOHOLISM, Issue 4 2009Paul R. Marques Background:, Two types of transdermal electrochemical sensors that detect alcohol at the skin surface were evaluated. One, the AMS SCRAMÔ device, is locked onto the ankle and is based on a fuel cell sensor; the other, a Giner WrisTASÔ device, worn on the wrist, is based on a proton exchange membrane. SCRAM is used by several court systems in the United States to monitor alcohol offenders, WrisTAS, a research prototype, is not commercially available. Methods:, The 2 devices were worn concurrently by 22 paid research subjects (15 men, 7 women), for a combined total of 96 weeks. Subjects participated in both laboratory-dosed drinking to a target of 0.08 g/dl blood alcohol concentration (BAC), and normal drinking on their own; all subjects were trained to use and carry a portable fuel-cell breath tester for BAC determinations. Overall 271 drinking episodes with BAC , 0.02 g/dl formed the signal for detection,60 from laboratory dosing, and 211 from self-dosed drinking, with BAC ranging from 0.02 to 0.230 g/dl (mean 0.077 g/dl). Results:, False negatives were defined as a transdermal alcohol concentration response equivalent <0.02 g/dl when BAC , 0.02 g/dl. The overall true-positive hit rate detected by WrisTAS was 24%. The low detection rate was due to erratic output and not recording during nearly 67% of all episodes; reportedly a chipset, not a sensor problem. SCRAM correctly detected 57% across all BAC events, with another 22% (total 79%) detected, but as <0.02 g/dl. When subjects dosed themselves to BAC , 0.08 g/dl, SCRAM correctly detected 88% of these events. SCRAM devices lost accuracy over time likely due to water accumulation in the sensor housing. Neither unit had false-positive problems when true BAC was <0.02 g/dl. Conclusions:, Each device had peculiarities that reduced performance, but both types are able to detect alcohol at the skin surface. With product improvements, transdermal sensing may become a valuable way to monitor the alcohol consumption of those who should be abstaining. [source] ChemInform Abstract: One-Step Synthesized HPW/meso-Silica Inorganic Proton Exchange Membranes for Fuel Cells.CHEMINFORM, Issue 37 2010Haolin Tang Abstract A proton exchange membrane based on the self-assembled mesoporous H3PW12O40/SiO2 nanocomposite is synthesized from mixtures of H3PW12O40, Si(OEt)4, EtOH, and H2O (molar ratio of 0.007:1:11:2.5) in the presence of P123 surfactant (40 °C, 7 d). [source] Sm1.5Sr0.5MO4 (M=Ni, Co, Fe) Cathode Catalysts for Ammonia Synthesis at Atmospheric Pressure and Low TemperatureCHINESE JOURNAL OF CHEMISTRY, Issue 4 2009Gaochao XU Abstract Sm1.5Sr0.5MO4 (M=Ni, Co, Fe) (SSM) catalysts were prepared by a sol-gel method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen at atmospheric pressure and low temperature (25,100 °C) with applied voltage, using SSM as a cathode, Ni-Ce0.8Sm0.2O2,,(Ni-SDC) as an anode, and silver-platinum film as a current collector, Nafion proton exchange membrane as a proton permeating membrane. Several important factors on ammonia synthesis were investigated and the optimal synthetic temperature was found, at which the highest rate of evolution of ammonia was up to 1.05×10,8 mol·cm,2·s,1. [source] Sulfonated poly(ether sulfone)s with binaphthyl units as proton exchange membranes for fuel cell applicationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Kazuya Matsumoto Abstract Sulfonated poly(ether sulfone)s containing binaphthyl units (BNSHs) were successfully prepared for fuel cell application. BNSHs, which have very simple structures, were easily synthesized by postsulfonation of poly(1,1,-dinaphthyl ether phenyl sulfone)s and gave tough, flexible, and transparent membranes by solvent casting. The BNSH membranes showed low water uptake compared to a typical sulfonated poly(ether ether sulfone) (BPSH-40) membrane with a similar ion exchange capacity (IEC) value and water insolubility, even with a high IEC values of 3.19 mequiv/g because of their rigid and bulky structures. The BNSH-100 membrane (IEC = 3.19 mequiv/g) exhibited excellent proton conductivity, which was comparable to or even higher than that of Nafion 117, over a range of 30,95% relative humidity (RH). The excellent proton conductivity, especially under low RH conditions, suggests that the BNSH-100 membrane has excellent proton paths because of its high IEC value, and water insolubility due to the high hydrophobicity of the binaphthyl structure. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5827,5834, 2009 [source] Synthesis and characterization of sulfonated-fluorinated, hydrophilic-hydrophobic multiblock copolymers for proton exchange membranesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2009Xiang Yu Abstract Hydrophilic/hydrophobic block copolymers as proton exchange membranes (PEMs) has become an emerging area of research in recent years. These copolymers were obtained through moderate temperature (, 100 °C) coupling reactions, which minimize the ether-ether interchanges between hydrophobic and hydrophilic telechelic oligomers via a nucleophilic aromatic substitution mechanism. The hydrophilic blocks were based on the nucleophilic step polymerization of 3,3,-disulfonated, 4,4,-dichlorodiphenyl sulfone with an excess 4,4,-biphenol to afford phenoxide endgroups. The hydrophobic (fluorinated) blocks were largely based on decafluoro biphenyl (excess) and various bisphenols. The copolymers were obtained in high molecular weights and were solvent cast into tough membranes, which had nanophase separated hydrophilic and hydrophobic regions. The performance and structure-property relationships of these materials were studied and compared to random copolymer systems. NMR results supported that the multiblock sequence had been achieved. They displayed superior proton conductivity, due to the ionic proton conducting channels formed through the self-assembly of the sulfonated blocks. The nano-phase separated morphologies of the copolymer membranes were studied and confirmed by atomic force microscopy. Through control of a variety of parameters, including ion exchange capacity and sequence lengths, performances as high, or even higher than those of the state-of-the-art PEM, Nafion, were achieved. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1038,1051, 2009 [source] Synthesis and characterization of postsulfonated poly(arylene ether sulfone) diblock copolymers for proton exchange membranesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2009Shogo Takamuku Abstract Sulfonated poly(arylene ether sulfone) diblock copolymers were studied through the postsulfonation process. Two kinds of hydrophobic oligomers with a molecular weight of 20 kDa were prepared in advance as block sequences and then coupled together to obtain diblock copolymers. One oligomer was synthesized from bis(4-hydroxyphenyl) sulfone (BHPS) and 4,4,-difluorodiphenyl sulfone (DFDPS), which was thought to be incapable of postsulfonation. The other oligomer was synthesized from hydroquinone (HQ) and 4,4,-dichlorodiphenyl sulfone (DCDPS), which successfully proceeded to a hydrophilic sequence as a result of sulfonation onto the HQ moiety after the coupling reaction. Consequently, a diblock copolymer with high molecular weight was obtained; although its intrinsic viscosity was too low to form a tough membrane because of its high rigidity and high crystallinity. Therefore, the use of decafluorobiphenyl (10F) as a termination reagent was investigated with the aim of achieving higher coupling reactivity and a kinky property. As a result, a sulfonated diblock copolymer was successfully obtained with sufficient molecular weight and intrinsic viscosity to form the membrane, as well as with adequate thermal properties. It was observed that proton conductivity, water uptake, and the water diffusion coefficient increased with higher ion exchange capacity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 700,712, 2009 [source] Correlation between Morphology, Water Uptake, and Proton Conductivity in Radiation-Grafted Proton-Exchange MembranesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2010Sandor Balog Abstract An SANS investigation of hydrated proton exchange membranes is presented. Our membranes were synthesized by radiation-induced grafting of ETFE with styrene in the presence of a crosslinker, followed by sulfonation of the styrene. The contrast variation method was used to understand the relationship between morphology, water uptake, and proton conductivity. The membranes are separated into two phases. The amorphous phase hosts the water and swells upon hydration, swelling being inversely proportional to the degree of crosslinking. Hydration and proton conductivity exhibit linear dependence on swelling. Proton conductivity and volumetric fraction of water are related by a power law, indicating a percolated network of finely dispersed aqueous pores in the hydrophilic domains. [source] Physically and Chemically Cross-Linked Poly{[(maleic anhydride)- alt -styrene]- co -(2-acrylamido-2-methyl-1-propanesulfonic acid)}/Poly(ethylene glycol) Proton-Exchange MembranesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2007lser G. Devrim Abstract Novel proton exchange membranes were solvent-cast from DMF solutions of the terpolymers poly[(MA- alt -S)- co -AMPS], containing hydrophobic phenyl and reactive hydrophilic carboxylic and organo-sulfonic acid fragments with different compositions, and PEGs with different molecular weights and amounts. These membranes were formed as a result of physical (via H-bonding) and chemical (via PEG) cross-linking. The structures of membranes were confirmed by FT-IR and 1H- and 13C NMR spectroscopy. Mechanical and thermal properties, swellability, and proton conductivity of these membranes were significantly affected both by the chemical composition of the terpolymers (mainly the AMPS content) and also the cross-linker (PEG) molecular weight and content in the final form of the membranes. It was concluded that the membranes prepared by using the terpolymer with an AMPS content of 36.84 mol-% and PEG with a molecular weight of 1,450 and with an initial PEG content of 30 wt.-% are the most suitable ones for fuel cell applications. [source] Sulfonated poly(phenylene oxide) membranes as promising materials for new proton exchange membranesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2006Shifang Yang Abstract Poly(phenylene oxide) (PPO) was sulfonated to different ion exchange capacities (IECs) using chlorosulfonic acid as the sulfonating agent. Tough, ductile films were successfully cast from sulfonated PPO (SPPO) solutions in N -methyl-2-pyrrolidone or N,N -dimethylformamide. The obtained membranes had good thermal stability revealed by thermogravimetric analysis (TGA). Compared with an unsulfonated PPO membrane, the hydrophilicity and water uptake of the SPPO membranes were enhanced, as shown by reduced contact angles with water. The tensile test indicated that the SPPO membranes with IEC ranging from 0.77 to 2.63,meq/g were tough and strong at ambient conditions and still maintained adequate mechanical strength after immersion in water at room temperature for 24,hr. The results of wide-angle X-ray diffraction (WAXD) showed amorphous structures for PPO and SPPO while the peak intensity decreased after sulfonation. The proton conductivity of these SPPO membranes was measured as 1.16,×,10,2,S/cm at ambient temperature, which is comparable to that of Nafion 112 at similar conditions and in the range needed for high-performance fuel cell proton exchange membranes. Copyright © 2006 John Wiley & Sons, Ltd. [source] | |||||||||||||