Analyses of hierarchical structures in SBR rubber by using contrast-variation SANS; Effects of a silane coupling agent

Nakanishi, Yohei*; Shibata, Motoki*; Sawada, Satoshi*; Kondo, Hiroaki*; Motokawa, Ryuhei; Kumada, Takayuki; Yamamoto, Katsuhiro*; Mita, Kazuki*; Miyazaki, Tsukasa*; Takenaka, Mikihito*

Polymer, 306, p.127209_1 - 127209_7, 2024/06

https://doi.org/10.1016/j.polymer.2024.127209

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

https://doi.org/10.1126/science.aav7432

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Hierarchical structure analysis of graft-type polymer electrolyte membranes consisting of cross-linked polytetrafluoroethylene by small-angle scattering in a wide- range

Iwase, Hiroki*; Sawada, Shinichi; Yamaki, Tetsuya; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari

Macromolecules, 45(22), p.9121 - 9127, 2012/11

https://doi.org/10.1021/ma301415r

Fundamental understanding of the structure-property relationship of polymer electrolyte membranes (PEM) is prerequisite for a material design satisfying PEM performance requirement. Small-angle scattering in a wide- range was observed by focusing small-angle neutron scattering (FSANS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). The hierarchical structure of the PEM was characterized as being composed of conducting layers (graft domains) in lamellar stacks with 48-57 nm spacing on the surfaces of 480 nm diameter crystallites and ultra-small structures with a 1.7 nm correlation distance of the sulfonic acid groups in the conducting layers. From the change in the SAXS profiles as a function of grafting degrees, it was revealed that the graft domains around the crystallites were connected with the adjoining domains and thus, the PEMs with a higher degree of grafting had conductivity higher than that of Nafion.

Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) film investigated by time-resolved small-angle neutron scattering

Iwase, Hiroki*; Sawada, Shinichi; Yamaki, Tetsuya; Maekawa, Yasunari; Koizumi, Satoshi

International Journal of Polymer Science, 2011(2011), p.301807_1 - 301807_7, 2011/00

https://doi.org/10.1155/2011/301807

Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) (PTFE) film was examined by time-resolved small-angle neutron scattering (SANS). A crosslinked PTFE film, thickness of which is about 50m, was irradiated by -ray and immersed in a mixed solvent of styrene monomer and toluene. SANS elucidated that graft polymerization proceeds by two reaction processes (I) and (II). In process (I) at 0200 min, graft polymerization occurs at an interface between crystalline and amorphous PTFE domains and the grafted polystyrene segregates from PTFE, forming a thin layer with a sharp interface. In process (II) at 200600 min, grafted PS layer starts to bridge between crystalline domains. At the end of process (II), 40% of total crystalline PTFE domain is covered by the grafted PS chains.

Analysis of Hydraulic and Transport Characteristics in Fracture of Micro Structure Using Cell Automata

Nishiyama, Satoshi*; Uehara, Shinichi*; Yano, Takao*; Saito, Ryuhei*; Uchida, Masahiro; Sawada, Atsushi; Takebe, Atsuji

JNC TY8400 2005-007, 70 Pages, 2005/03

JNC-TY8400-2005-007.pdf:2.24MB

None

Relationship between structural and proton conductive properties of crosslinked-fluoropolymer-based electrolyte membranes; Consideration based on nanometer-to-micrometer hierarchical structures

Yamaki, Tetsuya; Motokawa, Ryuhei; Iwase, Hiroki*; Sawada, Shinichi; Asano, Masaharu; Koizumi, Satoshi; Maekawa, Yasunari

no journal, , 

The nanometer-to-micrometer hierarchical structure was investigated by small-angle neutron/X-ray scattering (SANS/SAXS) analysis, a dissipative particle dynamics (DPD) simulation, and transmission electron microscopy (TEM) observation and then discussed in relation to proton conductivity. In a macroscopic scale, 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 microscopically-aggregated ionic clusters basically appeared smaller than that of Nafion, and the phase-separated domain including them grew large by connecting with each other toward high ion exchange capacities. This morphological change was accompanied by an increase in the self-diffusion coefficient of protons mainly representing proton conductivity.

Nano-meso scale structures of radiation-grafted polymer electrolyte membranes investigated by small angle neutron scattering technique

Sawada, Shinichi; Yamaguchi, Daisuke; Putra, A.; Koizumi, Satoshi; Maekawa, Yasunari

no journal, , 

In order to develop the novel polymer electrolyte membranes (PEMs) with high performances, it is important to clarify the structures of conventional PEMs. In this study, we investigated the structures of the radiation grafted PEMs based on poly(ethylene-co-tetrafluoroethylene) (ETFE) films by a small angle neutron scattering (SANS) technique. From the SANS profile, the shoulder peak was observed at the wave number q=0.16nm. This result suggest that the domains containing poly(styrene sulfonic acid) (PSSA) graft chains should exist at constant intervals, corresponding to the correlation distance L=2/q=39 nm. The distance of ETFE lamellar stacks was reported to 27 nm, which is somewhat close to L. This indicates that the PSSA graft chains were introduced in the interfacial regions in lamellar stacks.

Development of hydrogen permselective membranes by radiation-induced graft polymerization into porous PVDF films

Hasegawa, Shin; Azami, Shinya*; Sawada, Shinichi; Hino, Satoshi*; Isobe, Shigehito*; Hashimoto, Naoyuki*; Maekawa, Yasunari

no journal, , 

Hydrogen permselective membranes, which have high hydrogen permeability (approximately 10 10 mol/(m s Pa) with selectivity against water and nitrogen, have been developed by radiation-induced graft polymerization (RIGP) of an acrylic acid (AAc), tetramethoxysirylstyrene (TMSS), and styrene(St) monomers into porous poly(vinylidene fluoride) (PVDF) films. The porosity of the prepared porous grafted PVDF were almost constant against grafting degrees. Thus, by hot press compression, the porosity of the grafted membranes was reduced to a 20-40% level. The hydrogen permeability of the compressed grafted PVDF is 10 10 mol/(m s Pa) with the hydrogen permselectivity of 3.2 and 3.5 against water and nitrogen, respectively. The above results indicate that RIGP of porous films with a hot press process is a very effective method to prepare hydrogen permselective membranes.

Structure and proton conductive properties of electrolyte membranes based on crosslinked polytetrafluoroethylene; Dissipative particle dynamics simulation and small angle neutron scattering study

Yamaki, Tetsuya; Sawada, Shinichi; Motokawa, Ryuhei; Asano, Masaharu; Koizumi, Satoshi; Maekawa, Yasunari

no journal, , 

We performed here dissipative particle dynamics simulation and small-angle neutron scattering (SANS) analysis to investigate the structure and proton conductive properties of crosslinked-polytetrafluoroethylene (PTFE)-based electrolyte membranes for fuel cell applications. A molecular structure was represented by a coarse-grained model, connecting soft spherical particles that corresponded to a group of several atoms. The simulated structure of the membranes with different hydration states and ion exchange capacities enabled us to explain the relationship between the water content and conductivity. The crosslinked-PTFE electrolyte membranes exhibited a SANS pattern being entirely different from Nafion's: an intense small-angle upturn in intensity and no well-defined peak. This demonstrates that they will possess the structural properties which cannot be rationalized by the so far presented models.

Structural analysis of radiation crosslinked- and grafted-polytetrafluoroethylene electrolyte membrane

Iwase, Hiroki; Koizumi, Satoshi; Hashimoto, Takeji; Yamaki, Tetsuya; Sawada, Shinichi; Maekawa, Yasunari

no journal, , 

By using ultra-small-angle neutron scattering (USANS) techniques, we have investigated the hierarchical structures of the crosslinked-polytetrafluoroethylene (PTFE) electrolyte membrane, which is made by using both radiation-crosslinking and radiation-induced grafting of styrene, in order to reveal the correlation between the hierarchical structure and a proton conducting mechanism. We observed structural changes of crosslinking PTFE electrolyte membrane in each synthetic process and compared the structures between the crosslinking PTFE electrolyte membrane and Nafion112 under swollen state. We detected each effects of radiation crosslinking and grafting, respectively on the scattering profiles. Scattering profile for swollen crosslinking PTFE electrolyte membrane in DO has a no peak around Q = 1.2 , where scattering profile for Nafion has a peak reflected the ion-cluster structure. However, a shoulder-like profile is appeared clearly at Q = 0.14 . This peak-position is agreement with that observed in the scattering profile after radiation-crosslinking process. The presented results suggested that the structure formed by the radiation-crosslinking is close relation with the proton conductivity for the crosslinking PTFE electrolyte membrane.