Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Enomoto, Kazuyuki; Takahashi, Shuichi; Rohani, R.; Maekawa, Yasunari
Journal of Membrane Science, 415-416, p.36 - 41, 2012/10
Times Cited Count：15 Percentile：46.12(Engineering, Chemical)Polymer electrolyte membranes (PEM) consisting of ion conducting alkylsulfonic acid and hydroxyl groups were successfully synthesized by radiation-induced graft polymerization of vinyl acetate (VAc) into a poly(ethylene-
-tetrafluoroethylene) (ETFE) film, followed by alkylsulfonation with 1,3-propanesulfone. The prepared PEM showed higher conductivity under 30% relative humidity at 80
C than that of the conventional poly(styrenesulfonic acid)-grafted ETFE. Furthermore, the prepared PEM also showed better mechanical properties than those of Nafion. Thus, the PEM with hydroxyl groups possesses sufficient mechanical and electrochemical properties, required for a fuel cell, operating at a high temperature and low humidity.
Enomoto, Kazuyuki; Takahashi, Shuichi; Maekawa, Yasunari
Macromolecular Chemistry and Physics, 213(1), p.72 - 78, 2012/01
Times Cited Count：10 Percentile：33.08(Polymer Science)Most polymer grafts in grafted polymer films obtained by radiation-induced solid graft polymerization have not been analyzed in detail due to difficulties in isolation of the grafts without structural decomposition. We report herein a novel structural and molecular weight characterization method for polymer grafts chemically attached to thermally and chemically stable polymer substrates, based on swelling-induced graft detachment in hot water. The polymer grafts prepared by radiation-induced polymerization of alkyl acrylate into poly(ethylene-co-tetrafluoroethylene) (ETFE) followed by a sulfonation reaction were found to have a ternary copolymer structure whose monomer units contained -COOH, -SO
H, or both.
Enomoto, Kazuyuki*; Takahashi, Shuichi*; Iwase, Takanori*; Yamashita, Takashi*; Maekawa, Yasunari
Journal of Materials Chemistry, 21(25), p.9343 - 9349, 2011/07
Times Cited Count：38 Percentile：72.35(Chemistry, Physical)The degradation manner of graft-type polymer electrolyte membranes consisting of hydrophilic poly(styrenesulfonic acid) (PSSA) graft polymers (grafts) and thermally and mechanically stable hydrophobic polymer substrates was examined in hot water. Severe weight loss was observed in PSSA-grafted cPTFE and ETFE films but not in a PSSA-grafted PEEK film. The decomposed extracts in water were characterized as PSSA during the whole course of degradation, clearly showing that the PSSA grafts detached from the fluorinated substrates without decomposition or scission of graft polymer chains. This is quite a new degradation manner for graft-type polymer electrolyte membranes; namely, hydrophilic PSSA grafts detach from hydrophobic polymer substrates due to swelling-induced stress at the interfacial boundary in the grafted films.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
Enomoto, Shuichi*; Kawamura, Hiroshi; Shirakawa, Yoshiyuki*; Nakanishi, Tomoko*; Nakamura, Kayoko*; Yano, Tsuneo*; Ido, Tatsuo*; Shibata, Tokushi
Isotope News, (657), p.2 - 11, 2009/01
The view of the future and the necessity of the system construction such as supply systems were shown about production of the medical diagnostics 
Mo and the silicon semiconductor on JMTR.
Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06
Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.
Nagame, Yuichiro; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Ishii, Yasuo; Sato, Tetsuya; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; et al.
Radiochimica Acta, 93(9-10), p.519 - 526, 2005/00
Times Cited Count：30 Percentile：87.1(Chemistry, Inorganic & Nuclear)no abstracts in English
Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shinichi; Nagame, Yuichiro; et al.
Journal of the American Chemical Society, 126(16), p.5219 - 5224, 2004/04
Times Cited Count：43 Percentile：72.51(Chemistry, Multidisciplinary)Fluoride complexation of element 104, rutherfordium (Rf), produced in the 
Cm(
O,5n)
Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchangechromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effect on the fluoride complexation of Rf.
Uchida, Shigeo*; Amano, Hikaru; Takahashi, Tomoyuki*; Chiba, Masaru*; Hisamatsu, Shunichi*; Enomoto, Shuichi*; Matsumoto, Shiro*
JAERI-Conf 2003-010, p.25 - 31, 2003/09
In the 3rd Stage Crossover Research (1998 to 2003), a project on Development of a dynamic transfer model of radionuclides in the soil ecosphere,is currently being promoted. The following five researches are carried out in this project. 1) Research into the forms of existence of nuclides and their change in the soil (NIRS and JAERI), 2) Research into the transition behavior of radionuclides in plants (IES, RIKEN and NIRS), 3) Research into the relation to the microorganism and on environmental remediation (RIKEN, JAERI and NIRS), 4) Research on the migration of radionuclides from atmosphere to soil and plant (MRI and JAERI), and 5) Database construction on transfer parameters (JAERI, NIRS and MRI). JAERI, MRI and NIRS are working on the development of a dynamic transfer model such as MOGRA for radionuclides on the basis of a gained knowledge about the environmental behavior through cooperation with universities, etc. This model is also capable of the predicting the behavior of materials that are harmful to the environment such as hazardous heavy metals discharged in the soil ecosphere. In this presentation, we will overview the ourcome of the 3rd stage research.
Enomoto, Kazuyuki; Takahashi, Shuichi; Maekawa, Yasunari
no journal, ,
The polymer electrolyte membranes consisting grafted sulfoalkyl ether on ETFE film were prepared. Grafting of vinyl acetate into the irradiated ETFE was carried out under Ar at 40 C. The grafting degrees increased with increasing an irradiation dose. The basic hydrolysis of poly(vinyl acetate) units in the grafting chain led to poly(vinyl alcohol) (PVA) in good yields. The sulfoalkylation of the hydroxyl group in the grafted PVA with 1,3-propanesultone was performed. A ring-opening reaction of 1,3-sultone induced by the nucleophilic addition of PVA gives sulfoalkyl ether in 70% yield. The ATR-IR spectrum of the membrane shows new peaks at 3369, 1647, and 1032 cm
, which are assigned to sulfoalkyl ether. The SEM-EDS image of the membrane shows a homogenous distribution of S atoms. The ion exchange capacity and proton conductivity of the membrane are estimated to be 1.6 mequiv g and 0.12 S cm, which are high enough for a fuel cell application.
Enomoto, Kazuyuki; Takahashi, Shuichi; Rohani, R.*; Maekawa, Yasunari
no journal, ,
The polymer electrolyte membranes consisting grafted sulfoalkyl ether on ETFE film were prepared. Grafting of vinyl acetate into the irradiated ETFE was carried out under Ar at 40 C. The grafting degrees increased with increasing an irradiation dose. The basic hydrolysis of poly(vinyl acetate) units in the grafting chain led to poly(vinyl alcohol) (PVA) in good yields. The sulfoalkylation of the hydroxyl group in the grafted PVA with 1,3-propanesultone was performed. A ring-opening reaction of 1,3-sultone induced by the nucleophilic addition of PVA gives sulfoalkyl ether in 70% yield. The ATR-IR spectrum of the membrane shows new peaks at 3369, 1647, and 1032 cm, which are assigned to sulfoalkyl ether. The SEM-EDS image of the membrane shows a homogenous distribution of S atoms. The ion exchange capacity and proton conductivity of the membrane are estimated to be 1.6 mequiv g and 0.12 S cm, which are high enough for a fuel cell application.
Enomoto, Kazuyuki; Takahashi, Shuichi*; Iwase, Takanori*; Yamashita, Takashi*; Maekawa, Yasunari
no journal, ,
Degradation mechanism of the graft-type polymer electrolyte membranes prepared by radiation techniques in the hot water have been studied in detail using UV-vis, GPC, NMR, and wide-angle X-ray scattering. The hydrothermal stability is found to be strongly related to the phase separation of the ion-containing hydrophilic grafts and hydrophobic polymers.
Maekawa, Yasunari; Takahashi, Shuichi; Iwase, Takanori*; Enomoto, Kazuyuki; Yamashita, Takashi*
no journal, ,
Degradation mechanism of the graft-type polymer electrolyte membranes prepared by radiation techniques in the hot water have been studied in detail using UV-vis, GPC, NMR, and wide-angle X-ray scattering. The hydrothermal stability is found to be strongly related to the phase separation of the ion-containing hydrophilic grafts and hydrophobic polymers.
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.
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.
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.
Enomoto, Kazuyuki; Takahashi, Shuichi*; Iwase, Takanori*; Yamashita, Takashi*; Iwase, Hiroki*; Koizumi, Satoshi; Maekawa, Yasunari
no journal, ,
The degradation behavior of graft-type polymer electrolyte membranes consisting of hydrophilic sulfo-containing graft polymers (grafts) in hydrophobic polymer substrates are examined; We employed poly(styrenesulfonic acid) (PSSA) as a hydrophilic grafts and crosslinked poly(tetrafluoroethylene) (cPTFE), poly(ethylene-co-tetrafluoroethylene) (ETFE), and poly(vinylidene fluoride) (PVDF) as a hydrophobic plastic substrate. PSSA-grafted cPTFE, ETFE, and PVDF films are degraded with more than 30 % weight loss in 85 C for 500 hours. The good agreement between losses of sulfo groups and film weights indicated that only PSSA grafts degraded from cPTFE, ETFE, and PVDF substrates. Using UV, NMR, and GPC, the decomposed extracts in water are confirmed to be PSSA with the same molecular weights. Furthermore, since the elemental analysis of the extracts did not have fluorine atoms, the grafts in all the PSSA-grafted films detach from the fluorinated substrates without decomposition. This is quite new degradation mode of graft-type polymer electrolyte membranes. By taking advantages of the interface abruption of swelled grafts, the chemically and thermally stable grafts attached onto the plastic films can be isolated and analyzed without special treatments.
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.
Maekawa, Yasunari; Enomoto, Kazuyuki; Takahashi, Shuichi; Hamakawa, Shotaro
no journal, ,
The polymer grafts (PSSA) attached on fluorinated polymer substrates (ETFE), which were prepared by radiation-induced grafting of styrene and subsequent sulfonation, were successfully isolated by swelling-induced detachment from the polymer substrates in hot water. Then, the number-averaged molecular weight (Mn) of the grafts can be determined using GPC. The Mn was almost constant but the number of grafting chains linearly increased with increasing grafting degrees. The above results clearly show that the radiation-induced grafting of styrene is gradually initiated during grafting period but rapidly terminated to give lower Mn, compared with that in polyethylene.
