The Experts below are selected from a list of 6699 Experts worldwide ranked by ideXlab platform
James M Fenton - One of the best experts on this subject based on the ideXlab platform.
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investigation of membrane property and fuel cell behavior with sulfonated poly ether ether ketone electrolyte temperature and relative humidity effects
2005Co-Authors: Ruichun Jiang, Russell H Kunz, James M FentonAbstract:Abstract Sulfonated poly(ether ether ketone)s (SPEEKs) with various Sulfonation degrees were prepared and characterized for the intention of fuel cell applications. Two distinct water vapor activity regions characterized by different water vapor uptake behaviors were observed. Proton conductivity of SPEEK membranes increases with increasing Sulfonation degrees and temperatures. SPEEK membranes with Sulfonation degrees of 51 and 60% show proton conductivity higher than 0.01 S cm−1 at temperatures higher than 40 °C with 100% relative humidity (RH). Relative humidity has a stronger effect on the proton conductivity of SPEEK membranes than that of Nafion® membranes. Fuel cell performance with SPEEK membranes was studied at various temperatures and relative humidities. Good fuel cell performance was obtained with a SPEEK-51 membrane at 80 °C, 100% relative humidity and ambient pressure. Both temperature and relative humidity have important influence to the cell resistances and performances. Cyclic voltammetry (CV) as well as hydrogen crossover profiles show distinct features under different relative humidity conditions.
Homayoun Moaddel - One of the best experts on this subject based on the ideXlab platform.
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preparation and characterization of nanocomposite membranes made of poly 2 6 dimethyl 1 4 phenylene oxide and montmorillonite for direct methanol fuel cells
2008Co-Authors: Mohammad Mahdi Hasanisadrabadi, Shahriar Hojjati Emami, Homayoun MoaddelAbstract:Abstract Partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (sulfonated PPO) with various degrees of Sulfonation were prepared. The solutions were mixed with organically modified montmorillonite (MMT) to prepare membranes by solvent casting. By increasing the Sulfonation degree up to 40% for membranes without MMT, ion exchange capacity, water uptake and proton conductivity reached 2.59 mequiv. g −1 , 21% and 0.0182 S cm −1 , respectively. The Fourier transfer infrared (FTIR) analysis of sulfonated membranes revealed absorption bands at 1060 and 1100–1300 cm −1 for sulfur–oxygen S O bonds. X-ray diffraction analysis showed the exfoliated structure of clay in polymeric matrices. A sulfonated PPO/MMT membrane with 27% Sulfonation and 2.0 wt% MMT loading showed a membrane selectivity of approximately 63,500 compared to 40,500 for Nafion ® 117, and also a higher power density (125 mW cm −2 ) than Nafion ® 117 (108 mW cm −2 ) for single cell DMFC in a 5 M methanol feed.
Weihua Yang - One of the best experts on this subject based on the ideXlab platform.
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a novel proton conductive membrane with reduced methanol permeability prepared from bromomethylated poly 2 6 dimethyl 1 4 phenylene oxide bppo
2008Co-Authors: Dan Wu, Rongqiang Fu, Tongwen Xu, Liang Wu, Weihua YangAbstract:Abstract A series of proton-conducting membranes were developed for direct methanol fuel cell (DMFC) applications via Sulfonation of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) base membranes. Besides the low manufacture cost, the membranes exhibited an excellent control on methanol crossover and swelling, and a sound balance with high proton conductivities. These can be attributed to the inherent properties of membrane structures: (i) benzyl substitution with bromine, which imparted the membrane stronger hydrophobicity, (ii) cross-linking between BPPO chains, which enhances the dimensional stability and renders the membrane a dense texture, (iii) proper content of sulfonic acid groups, which guarantees the proton conductivity. An optimal membrane was obtained after investigating the effects of the bromination degree and Sulfonation process on the performances of corresponding membranes, i.e. , the membrane possesses the methanol permeability of 2.64 × 10 −8 cm 2 /s and characteristic factor Φ value of 30 times higher than that of Nafion ® 117. The Sulfonation process should be controlled within a proper period of time and in mild Sulfonation conditions so as to achieve a proton conductivity higher than 0.07 S/cm for potential applications in DMFC.
Mohammad Mahdi Hasanisadrabadi - One of the best experts on this subject based on the ideXlab platform.
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preparation and characterization of nanocomposite membranes made of poly 2 6 dimethyl 1 4 phenylene oxide and montmorillonite for direct methanol fuel cells
2008Co-Authors: Mohammad Mahdi Hasanisadrabadi, Shahriar Hojjati Emami, Homayoun MoaddelAbstract:Abstract Partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (sulfonated PPO) with various degrees of Sulfonation were prepared. The solutions were mixed with organically modified montmorillonite (MMT) to prepare membranes by solvent casting. By increasing the Sulfonation degree up to 40% for membranes without MMT, ion exchange capacity, water uptake and proton conductivity reached 2.59 mequiv. g −1 , 21% and 0.0182 S cm −1 , respectively. The Fourier transfer infrared (FTIR) analysis of sulfonated membranes revealed absorption bands at 1060 and 1100–1300 cm −1 for sulfur–oxygen S O bonds. X-ray diffraction analysis showed the exfoliated structure of clay in polymeric matrices. A sulfonated PPO/MMT membrane with 27% Sulfonation and 2.0 wt% MMT loading showed a membrane selectivity of approximately 63,500 compared to 40,500 for Nafion ® 117, and also a higher power density (125 mW cm −2 ) than Nafion ® 117 (108 mW cm −2 ) for single cell DMFC in a 5 M methanol feed.
Arumugam Manthiram - One of the best experts on this subject based on the ideXlab platform.
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Sulfonated Poly(ether ether ketone) Membranes for Direct Methanol Fuel Cells
2003Co-Authors: B. Yang, Arumugam ManthiramAbstract:Sulfonated poly(ether ether ketone) (SPEEK) with different degrees of Sulfonation has been prepared and evaluated as proton exchange membrane electrolytes in direct methanol fuel cells (DMFCs). The membranes have been characterized by ion-exchange capacity, proton conductivity, and liquid uptake measurements. The proton conductivity of the SPEEK membranes increases with increasing Sulfonation level, and are lower than that of Nafion. The percent liquid uptake increases with increasing temperature, methanol concentration, and degree of Sulfonation. Within a narrow range of Sulfonation of ∼50%, the SPEEK membranes exhibit electrochemical performances comparable to or exceeding that of Nafion at 65°C, making it an attractive low-cost alternative to Nafion. The better performance of the SPEEK membranes is due to the suppression of methanol permeability as indicated by a lower methanol crossover current density at the cathode.
