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Nafion-Sulfonated Poly(arylene ether sulfone) Composite Membrane for Direct Methanol Fuel Cell
Choi Jisu,Kim II Tae,Kim Sung Chul,Hong Young Taik The Polymer Society of Korea 2005 Macromolecular Research Vol.13 No.6
Composite membranes of Nafion and sulfonated poly(arylene ether sulfone) were prepared. Sulfonated poly(arylene ether sulfone)s with different degrees of sulfonation were blended with Nafion to reduce the methanol crossover. The morphology, proton conductivity and methanol permeability of the resulting composite membranes were investigated by SEM, EDAX, AC impedance spectroscopy and permeability measuring instrument. The crosssections of the composite membranes showed a phase separated morphology. The morphology and phase separation mechanism could be controlled by varying the blend ratio and the degree of sulfonation of poly(arylene ether sulfone). These complex morphologies can be applied for reducing methanol crossover. The methanol permeability and proton conductivity of the composite membranes were lower than those of Nafion 117 membrane since the development of an ionic pathway in the blend membrane was more difficult than that in Nafion itself.
Jisu Choi,Dongbok Shin,임헌경 한국지질과학협의회 2018 Geosciences Journal Vol.22 No.1
Metallic ore deposits of various genetic types are distributed in the Taebaeksan mineralized district in South Korea. The different basements or host rocks for these deposits vary across the northern and southern regions of the district with the Baegunsan Syncline as its center. Previous and newly analyzed sulfur isotope data of 374 sulfide minerals collected from 45 ore deposits were reviewed to compare the genetic characteristics of the two regions. Metallic deposits in the study area were classified into skarn, hydrothermal replacement, and hydrothermal vein based on genetic types and W-Mo, Fe-Cu(-Mo-Pb-Zn), Pb-Zn(-Cu-Au- Ag), and Au-Ag(-Cu-Pb-Zn) deposits with regard to ore species. For each genetic type, average sulfur isotope values were found to be 6.8‰, 7.7‰, and 6.3‰ in the northern region, and 2.3‰, 3.6‰, and 3.5‰ in the southern region, respectively. Average sulfur isotope values for each of the ore species were 11.3‰, 2.6‰, 6.6‰, and 6.9‰ in the northern region, and 1.3‰, –0.2‰, 4.2‰, and 3.3‰ in the southern region, respectively. The results indicate that sulfur isotope compositions for both genetic types and ore species are distinctly higher in the northern region than in the southern region. These differences could be ascribed to different sulfur isotope compositions of basement and host rocks that provided sulfur to ore minerals during the evolution of hydrothermal fluids, though the mineralizing fluids were originated from magmatic source. In the northern region, higher δ34S values of ore sulfurs could be attributed to high δ34S values of sulfate and sulfide in carbonate rocks formed in seawater. On the contrary, lower δ34S values of sulfide minerals in the southern region seem to be attributed to metasedimentary rocks that have lower δ34S values as a result of bacterial sulfate reduction.