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Iwai, Yasunori; Yamanishi, Toshihiko
Polymer Degradation and Stability, 94(4), p.679 - 687, 2009/04
Times Cited Count：47 Percentile：81.1(Polymer Science)The effect of exchanged ions on the thermal stability of Nafion N117CS membranes was investigated. The ion exchange of alkaline metal ions was effective in improving the thermal stability of the Nafion N117CS membrane. We confirmed that the Na-exchange Nafion N117CS membrane possessed a distinctive degree of thermal stability among the alkaline ion-exchange Nafions. Thermal stability improved the most when the Nafion membrane was exchanged for alkaline ions, followed by divalent ions, then trivalent ions. As for the Nafion membrane when it was exchanged for divalent ions or trivalent ions, Nafion following the ion exchange had a thermal stability proportional to an increase in the ionic radius of the cation. The activation of molecular mobility in Nafion was observed between the decomposition stages of the loss of water and the loss of sulfonic groups. The temperature of activation of cation-exchange Nafion became much higher than that of Nafion in an acid form.
Sawada, Shinichi; Yamaki, Tetsuya; Kawahito, Shimpei*; Asano, Masaharu; Suzuki, Akihiro*; Terai, Takayuki*; Maekawa, Yasunari
Polymer Degradation and Stability, 94(3), p.344 - 349, 2009/03
Times Cited Count：7 Percentile：24.69(Polymer Science)We investigated thermal properties of proton exchange membranes (PEMs) prepared by the radiation-induced grafting of styrene into crosslinked-polytetrafluoroethylene films and the subsequent sulfonation for fuel cell applications. A conventional thermogravimetric analysis was found to be unreliable because the resulting curve varied greatly with the heating rate. Thus, in order to obtain accurate information, we performed an ex-situ heat-treatment analysis, which involved heating of the PEMs at fixed temperatures of 200-350
C and measurement of their remaining weight, ion exchange capacity (IEC) and proton conductivity after washing in pure water. The IEC and conductivity did not change at any temperature up to 200C, indicating high thermal stability. At 250C, however, the PEM properties deteriorated probably via radical cleavage of the C-S bond between a sulfonic acid group and an aromatic ring, and condensation of two sulfonic acid groups.
Darwis, D.*; Mitomo, Hiroshi*; Yoshii, Fumio
Polymer Degradation and Stability, 65(2), p.279 - 285, 1999/08
Times Cited Count：41 Percentile：80.5(Polymer Science)no abstracts in English
