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Maekawa, Yasunari; Enomoto, Kazuyuki; Takahashi, Shuichi*; Iwase, Takanori*; Yamashita, Takashi*; Iwase, Hiroki*; Koizumi, Satoshi
no journal, ,
Detachment of sulfonated grafts in graft-type polymer electrolyte membranes (PEM) were observed in hot water. The detachment is assisted by the interface stress between swelling of the hydrophilic grafts and hydrophobic polymer substrates. The grafted PEM with a clear phase separation structure, observed by small angle neutron scattering (SANS), are subjected to fast detachment of the grafts.
Enomoto, Kazuyuki; Takahashi, Shuichi; Oba, Haruna*; Kihara, Nobuhiro*; Maekawa, Yasunari
no journal, ,
Polymer electrolyte membranes (PEM) with sulfoalkyl grafts containing carboxylic acid and hydroxyl groups into a poly(ethylene-co-tetrafluoroethylene) film can be synthesized, based on the base-catalyzed nucleophilic addition of 1,3-propane sultone with poly(vinyl alcohol) grafts or with poly(2-hydroxymethyl methacrylate) grafts. The PEM with the grafts containing hydroxyl groups showed higher ion conductivity than conventional graft-type PEM at low relative humidity.
Asano, Masaharu; Chen, J.; Li, D.*; Maekawa, Yasunari
no journal, ,
no abstracts in English
Matsuura, Hirotaka*; Fujii, Yuki*; Jo, Akinori*; Katakai, Akio; Tamada, Masao
no journal, ,
no abstracts in English
Jo, Akinori*; Kato, Shota*; Matsuura, Hirotaka*; Nagata, Kazumi*; Katakai, Akio; Tamada, Masao
no journal, ,
no abstracts in English
Hasegawa, Shin; Iwase, Hiroki; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari
no journal, ,
Radiation grafting of ethyl styrylsulfonate (EtSS) onto poly(ether ether ketone) (PEEK) film with various crystallinity was performed. The crystallinity in the range of 10
30% has strong influence on the grafting degrees. The PEEK film with crystallinity of 1125% showed any dose effect on grafting degrees with 60%. By SAXS analysis, it was found that grafting process strongly depended on lamellar structure into PEEK membrane.
Koizumi, Satoshi; Hirokawa, Yoshitsugu*; Hashimoto, Takeji
no journal, ,
no abstracts in English
Yamaki, Tetsuya; Motokawa, Ryuhei; Iwase, Hiroki*; Sawada, Shinichi; Asano, Masaharu; Koizumi, Satoshi; Maekawa, Yasunari
no journal, ,
The nanometer-to-micrometer hierarchical structure of cPTFE-based electrolyte membranes was investigated by SANS or SAXS analysis, DPD simulation and transmission electron microscopy observation. The grafting reaction was found to occur in a PTFE amorphous layer between rigid lamellar crystals and, however, a main reaction field was the outside of the lamellae, which would determine proton conductivity of the membranes. The ionic clusters basically appeared smaller than that of Nafion, and the phase-separated domain including them grew large by connecting with each other towards high ion exchange capacities. This morphological change was accompanied by an increase in the self-diffusion coefficient of protons representing proton conductivity.
Putra, A.; Koizumi, Satoshi; Yamaguchi, Daisuke; Iwase, Hiroki*; Maekawa, Yasunari; Matsubayashi, Masahito; Hashimoto, Takeji
no journal, ,
In-situ observation to visualize water generated inside an operating polymer electrolyte fuel cell (PEFC) in a wide length scale from nanometer to millimeter has been done by a combined method of small-angle neutron scattering (SANS) and neutron radiography (NR). The NR apparatus composed of a scintillator, optical mirrors and a CCD camera, was installed at a sample position of the focusing and SANS spectrometer (SANS-J-II) at research reactor JRR-3 in Japan Atomic Energy Agency, Tokai, Japan. This new method succeeded in detecting a spatial distribution of the water generated in individual cell elements; NR detected the water in a gas diffusion layer and a flow-field, whereas SANS quantitatively determines the water content in a membrane electrode assembly (MEA).