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Journal Articles

$$Q$$-dependent collective relaxation dynamics of glass-forming liquid Ca$$_{0.4}$$K$$_{0.6}$$(NO$$_{3}$$)$$_{1.4}$$ investigated by wide-angle neutron spin-echo

Luo, P.*; Zhai, Y.*; Falus, P.*; Garc$'i$a Sakai, V.*; Hartl, M.*; Kofu, Maiko; Nakajima, Kenji; Faraone, A.*; Z, Y.*

Nature Communications (Internet), 13, p.2092_1 - 2092_9, 2022/04

 Times Cited Count:1 Percentile:48.58(Multidisciplinary Sciences)

Journal Articles

Port-based plasma diagnostic infrastructure on ITER

Pitcher, C. S.*; Barnsley, R.*; Bertalot, L.*; Encheva, A.*; Feder, R.*; Friconneau, J. P.*; Hu, Q.*; Levesy, B.*; Loesser, G. D.*; Lyublin, B.*; et al.

Fusion Science and Technology, 64(2), p.118 - 125, 2013/08

 Times Cited Count:4 Percentile:32.63(Nuclear Science & Technology)

The port-based plasma diagnostic infrastructure on ITER is described, including the port plugs, the interspace support structure and port cell structure. These systems are modular in nature with standardized dimensions. The design of the equatorial and upper port plugs and their modules is discussed, as well as the dominant loading mechanisms. The port infrastructure design has now matured to the point that port plugs are now being populated with multiple diagnostics supplied by a number of ITER partners - two port plug examples are given.

Journal Articles

Nuclear engineering of diagnostic port plugs on ITER

Pitcher, C. S.*; Barnsley, R.*; Feder, R.*; Hu, Q.*; Loesser, G. D.*; Lyublin, B.*; Padasalagi, S.*; Pak, S.*; Reichle, R.*; Sato, Kazuyoshi; et al.

Fusion Engineering and Design, 87(5-6), p.667 - 674, 2012/08

 Times Cited Count:12 Percentile:66.72(Nuclear Science & Technology)

Journal Articles

Modification of ultrathin polyetheretherketone film for application in direct methanol fuel cells

Chen, J.; Li, D.; Koshikawa, Hiroshi; Zhai, M.*; Asano, Masaharu; Oku, Hiroyuki*; Maekawa, Yasunari

Journal of Membrane Science, 344(1-2), p.266 - 274, 2009/11

 Times Cited Count:15 Percentile:46.58(Engineering, Chemical)

An ultrathin polyetheretherketone (PEEK) film was modified by thermal grafting of divinylbenzene (DVB) followed by radiation grafting of ethyl styrenesulfonate (ETSS), to develop a polymer electrolyte membrane (PEM) for use in direct methanol fuel cells (DMFCs). The DVB-grafting yield by thermal polymerization was less than 7%, but was sufficient to enhance the subsequent ETSS-grafting. The ETSS units were converted to styrenesulfonic acid (SS) units by hydrolysis in hot water, resulting in an ultrathin PEEK-g-DVB-g-SS PEM. FT-IR and TG analysis as well as measurements for the ion exchange capacity, water uptake, proton conductivity, mechanical strength, and methanol permeability were performed. Furthermore, this new PEM was tested in a DMFC, and a high maximum power density was confirmed. Therefore, we conclude that this modified PEEK film can be used as the PEM for the application in DMFCs.

Journal Articles

Performance of vanadium redox flow battery with a novel amphoteric ion exchange membrane synthesized by two-step grafting method

Qiu, J.*; Zhai, M.*; Chen, J.; Wang, Y.*; Peng, J.*; Xu, L.*; Li, J.*; Wei, G.*

Journal of Membrane Science, 342(1-2), p.215 - 220, 2009/10

 Times Cited Count:74 Percentile:91.21(Engineering, Chemical)

A novel ETFE-based amphoteric ion exchange membrane (AIEM) was prepared through a two-step radiation induced grafting technique. ETFE film was first grafted with styrene (St) (denoted as ETFE-$$g$$-PS), followed with a sulfonation treatment to obtain a cation exchange membrane (ETFE-$$g$$-PSSA). The ETFE-$$g$$-PSSA membrane was subsequently grafted with dimethylaminoethyl methacrylate (DMAEMA) and then protonated, resulting in an AIEM with both anionic and cationic groups. The obtained AIEM exhibited high ion exchange capacity (IEC) and conductivity, as well as significantly reduced permeability of vanadium ions. Vanadium redox flow battery (VRFB) assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.3V after placed for 300h, and exhibited higher columbic efficiency and energy efficiency than that with Nafion117 membrane.

Journal Articles

Long-term performance of polyetheretherketone-based polymer electrolyte membrane in fuel cells at 95$$^{circ}$$C

Chen, J.; Zhai, M.*; Asano, Masaharu; Huang, L.*; Maekawa, Yasunari

Journal of Materials Science, 44(14), p.3674 - 3681, 2009/07

 Times Cited Count:25 Percentile:59.61(Materials Science, Multidisciplinary)

A poly(styrenesulfonic acid)-grafted polyetheretherketone (ssPEEK) polymer electrolyte membrane was developed by radiation grafting of ethyl styrenesulfonate (ETSS) onto PEEK film and subsequent hydrolysis. The long-term durability of the ssPEEK membrane was tested in a fuel cell, and it exhibited a lifetime of more than 1,000 h and a slow voltage degradation. After durability test, the catalyst layers were analyzed by XRD and TEM; the membrane was investigated by determining the change in thickness, proton conductivity and amounts of sulfonic acid groups. It was concluded that the degradation of performance in fuel cell was due to the thermal aging of the hydrocarbon membrane exposed to the electrochemical environment using the pure oxygen as the oxidant gas, as well as the Nafion-based catalyst layer being subject to high temperature for a long time, where the Pt catalyst was aggregated and sintered.

Journal Articles

Perfluorinated polymer film with functional group prepared by radiation-induced grafting

Zhai, M.; Chen, J.; Hasegawa, Shin; Li, D.; Oku, Hiroyuki*; Maekawa, Yasunari

European Polymer Journal, 45(6), p.1668 - 1673, 2009/06

 Times Cited Count:6 Percentile:21.71(Polymer Science)

A perfluorinated vinyl ether monomer, 2-bromotetrafluoroethyl trifluorovinyl ether (BrTFF) was grafted into crosslinked poly(tetrafluoroethylene) (cPTFE) films by $$gamma$$-rays irradiation under different conditions. The irradiation with absorbed doses more than 550 kGy gave the poly(BrTFF) grafted cPTFE membranes with grafting yields of more than 20%. FTIR spectra and SEM-EDS testified that BrTFF was successfully grafted into cPTFE films homogeneously in the film perpendicular direction. TGA analysis of the grafted films indicated that the perfluorinated poly(BrTFF) grafts were phase-separated from the PTFE region due to the crosslinked structure of the cPTFE based film, but the grafted films still had high thermal stability (above 300 $$^{circ}$$C). The grafted film, a new kind of perfluorinated polymer with bromine active groups and good mechanical properties, is expected to be modified for new applications.

Journal Articles

Amphoteric ion exchange membrane synthesized by radiation-induced graft copolymerization of styrene and dimethylaminoethyl methacrylate into PVDF film for vanadium redox flow battery applications

Qiu, J.*; Zhang, J.*; Chen, J.; Peng, J.*; Xu, L.*; Zhai, M.*; Li, J.*; Wei, G.*

Journal of Membrane Science, 334(1-2), p.9 - 15, 2009/05

 Times Cited Count:86 Percentile:93.19(Engineering, Chemical)

Poly(vinylidene difluoride) (PVDF) film was grafted with styrene (St) and dimethylaminoethyl methacrylate (DMAEMA) using irradiation techniques. Through subsequent sulfonation and protonation processes, a new kind of amphoteric ion exchange membrane (AIEM) was synthesized. The grafting yield ($$GY$$) increased with absorbed dose and leveled off at about 60 kGy. The properties of the AIEM strongly depended on the composition and $$GY$$ of the film, i.e. higher content of DMAEMA brought lower permeability of vanadium ions and conductivity. Finally, an AIEM was assembled and tested in the vanadium redox flow battery (VRFB) system. It was found that the VRFB assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.2V after placed for 68h, which was much longer than that with the Nafion117 membrane. Therefore, this work provides a novel method to develop potential substitute of Nafion membranes to be applied in VRFB system.

Journal Articles

Synthesis of fluorinated polymer electrolyte membranes by radiation grafting and atom transfer radical polymerization techniques

Zhai, M.; Chen, J.; Hasegawa, Shin; Maekawa, Yasunari

Polymer, 50(5), p.1159 - 1165, 2009/03

 Times Cited Count:30 Percentile:68.43(Polymer Science)

A novel polymer electrolyte membrane was synthesized by radiation-induced grafting and consequent atom transfer radical polymerization (ATRP) using a fluorinated substrate polymer. First, bromine-containing perfluorinated grafts were prepared by radiation grafting. By adjusting the molar ratio of bromine-initiator/CuBr/bpy and the reaction temperature, branched poly(styrene) with a grafting yield of above 100% on the perfluorinated grafts was constructed in the films. Thermal analysis revealed that the perfluorinated grafts were miscible to the fluorinated substrate polymer, whereas the hydrocarbon poly(styrene) branches were phase-separated from the fluorinated film. The sulfonation of the poly(styrene) grafts gave the membrane exhibiting higher proton conductivity than commercial Nafion 117 membrane. Likewise, it had better chemical stability than graft-type membranes prepared by conventional radiation-induced grafting.

Journal Articles

Hydrocarbon proton-conductive membranes prepared by radiation-grafting of styrenesulfonate onto aromatic polyamide films

Li, D.*; Chen, J.; Zhai, M.; Asano, Masaharu; Maekawa, Yasunari; Oku, Hiroyuki*; Yoshida, Masaru

Nuclear Instruments and Methods in Physics Research B, 267(1), p.103 - 107, 2009/01

 Times Cited Count:28 Percentile:86.67(Instruments & Instrumentation)

Novel method for preparing aromatic hydrocarbon proton-conductive membranes without sulfonation and membrane casting process is achieved by radiation grafting of sodium styrenesulfonate to an aromatic polyamide, poly(m-xylylene adipamide) (Nylon-MXD6) films and subsequent ion-exchange. The styrenesulfonate was easily grafted into the Nylon-MXD6 films from an oxygen-free dimethyl sulfoxide (DMSO) solution. As a result, the resulted styrenesulfonic acid-grafted Nylon-MXD6 films, namely proton-conductive membrane, with high ion exchange capacity up to 1.63 mmol/g, can be obtained. The membrane was transparent and highly hydrophilic. Furthermore, the methanol permeability was significantly lower than that of the Nafion membrane. Therefore, the Nylon-MXD6-based proton-conductive membrane is a more promising material for the direct methanol fuel cells (DMFCs).

Journal Articles

Radiation-induced grafting of perfluorinated vinyl ether into fluorinated polymer films

Zhai, M.; Hasegawa, Shin; Chen, J.; Maekawa, Yasunari

Journal of Fluorine Chemistry, 129(12), p.1146 - 1149, 2008/12

 Times Cited Count:16 Percentile:54.47(Chemistry, Inorganic & Nuclear)

We report herein the first successful grafting of perfluorinated vinyl ether monomer into base polymer films by simultaneous radiation method. 2-Bromotetrafluoroethyl trifluorovinyl ether (BrTFF) could be grafted into poly(ethylene-co-tetrafluoroethylene) (ETFE) films by $$gamma$$-rays irradiation at room temperature. The grafting yield increased linearly with an increase in the dose up to 1400 kGy. The required dose for a satisfactory grafting yield, such as 20%, was as high as ca. 400 kGy probably due to low polymerization reactivity of fluorinated monomers. The thermal analysis of the grafted films indicated no phase separation between poly (BrTFF) grafts and ETFE films, probably owing to high compatibility of the fluorinated grafts and base polymers.

Journal Articles

Radiation effects on hydroxypropyl methylcellulose phthalate in aqueous system

Xu, L.*; Yue, Z.*; Wang, M.*; Zhai, M.*; Yoshii, Fumio; Seko, Noriaki; Peng, J.*; Wei, G.*; Li, J.*

Nuclear Instruments and Methods in Physics Research B, 265(1), p.394 - 398, 2007/12

 Times Cited Count:5 Percentile:40.99(Instruments & Instrumentation)

A water insoluble cellulose derivative, hydroxypropyl methylcellulose phthalate (HPMCP) hydrogels, was converted to Na type to form hydrogel in paste-like status by radiation crosslinking. Mechanism for radiation crosslinking of cellulose-derivatives in paste-like status was discussed. Crosslinkers, i.e., methyl $$N,N$$-bis-acrylamide (MBA) or ethyleneglycol dimethacrylate (EGDMA) has been used to decrease gelation dose (Dg) of synthesis HPMCP hydrogels and improve its mechanical properties. MBA was found to be more effective for accelerating the crosslinking of HPMCP than EGDMA. Swelling degree of HPMCP hydrogel in many kinds ofsalt solutions followed Hofmeister series, which is ubiquitous in polyelectrolyte hydrogel. Specific reswelling was observed in concentrated KF solution, implying a very strong F$$^{-}$$ binding ability of benzyl group. The comprehensive results obtained in this study will be utilized on the design of HPMCP-based controlled release system.

Journal Articles

Synthesis of antibacterial PVA/CM-chitosan blend hydrogels with electron beam irradiation

Zhao, L.; Mitomo, Hiroshi*; Zhai, M.*; Yoshii, Fumio; Nagasawa, Naotsugu; Kume, Tamikazu

Carbohydrate Polymers, 53(4), p.439 - 446, 2003/09

 Times Cited Count:197 Percentile:99.05(Chemistry, Applied)

no abstracts in English

Journal Articles

Syntheses of PVA/starch grafted hydrogels by irradiation

Zhai, M.*; Yoshii, Fumio; Kume, Tamikazu; Hashim, K.*

Carbohydrate Polymers, 50(3), p.295 - 303, 2002/11

 Times Cited Count:176 Percentile:98.71(Chemistry, Applied)

no abstracts in English

Journal Articles

Improvement of mechanical properties of hydrogel by irradiation of polymers in aqueous solution with $$kappa$$-carrageenan

Makuuchi, Keizo; Yoshii, Fumio; Aranilla, C. T.*; Zhai, M.*

JAERI-Conf 2000-001, p.192 - 195, 2000/03

no abstracts in English

Journal Articles

Interaction of externally applied rotating helical field with tokamak plasma

Kobayashi, M.*; Tsuda, Takashi; Tashiro, Kenji*; Kojima, H.*; Zhai, K.*; Takamura, Shuichi*

Nuclear Fusion, 40(2), p.181 - 193, 2000/02

 Times Cited Count:27 Percentile:63.23(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

Polyetheretherketone-based polymer electrolyte membranes for fuel cells prepared by radiation techniques

Chen, J.; Zhai, M.; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru

no journal, , 

Polymer electrolyte membrane fuel cells are very promising as power sources for automotive applications, where stability and durability at a high temperature and low humidity are demanded. The currently used expensive Nafion membranes are not appropriated for application in high temperature fuel cells. For this reason, an inexpensive polyetheretherketone (PEEK)-based polymer electrolyte membrane (ssPEEK) was prepared by successive two-step grafting of divinylbenzene and ethyl styrenesulfonate onto PEEK film, followed by hydrolysis of the ETSS graft chains to form styrenesulfonate graft chains. The results of the fuel cell test showed that ssPEEK has a performance comparable to Nafion at lower temperature and higher humidify, and much better performance at higher temperature and lower humidify. In addition, at the latter, the ssPEEK-based cell could be operated with stable performance for more than 250 h without any substantial voltage drop, whereas the voltage of the Nafion-based cell continuously dropped over the same duration.

Oral presentation

Synthesis of fluorinated polymer electrolyte membranes by radiation-induced grafting and atom transfer radical polymerization techniques

Zhai, M.; Hasegawa, Shin; Chen, J.; Maekawa, Yasunari

no journal, , 

To develop a highly chemicallly stable polymer electrolyte membrane for appilcation in a direct methanol fuel cell, a fluorinated monomer, Bromotetrafluoroethyl trifluorovinyl ether (BrTFF), was grafted firstly into poly(ethylene-co-tetrafluoroethylene) (ETFE) membrane by irradiation. Further, a new-type polymer electrolyte membrane was synthesized by atom transfer radical polymerization of styrene into ETFE-graft-polyBrTFF membrane followed by sulfonation. The bromine groups in ETFE-graft-polyBrTFF membrane functioned as initiators, and a Cu-based catalytic system of Cu(I)Br and bipyridyl (bpy) was empolyed for the ATRP. It was found that styrene was grafted homogeneously into ETFE-graft-polyBrTFF membrane and the prepared polymer electrolyte membrane have higher ion exchange capacity (IEC) and proton conductivity than that of normal ETFE-g-PSSA membrane.

Oral presentation

Solid state radiation grafting of perfluoro vinylether for proton exchange membranes

Hasegawa, Shin; Zhai, M.; Maekawa, Yasunari

no journal, , 

To develop a chemically stable polymer electrolyte membrane for application in a fuel cell, fluorinated polymer membranes were prepared by radiation-induced graft polymerization. A fluorinated monomer containing sulfonic acid precursor (perfluoro(4-methyl-1, 3,6-dioxaoct-7-ene) sulfonylfluoride (PFMDS)) could be grafted into ETFE with grafting degrees of 24%(1320 kGy at 50 degree Celsius) by stimulus irradiation. The grafted films were successfully transformed into electrolyte membranes by hydrolysis (IEC = 0.39 mmol/g $$sigma$$ = 0.03 S/cm).

Oral presentation

Preparation and characteristics of ultra-thin PEEK-based polymer electrolyte membranes

Li, D.*; Chen, J.; Zhai, M.*; Asano, Masaharu; Maekawa, Yasunari; Oku, Hiroyuki*; Yoshida, Masaru

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)