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Journal Articles

Gelation process of polyacrylonitrile solutions as studied using small-angle neutron scattering techniques

Nakano, Shota*; Konno, Soken*; Tomita, Naoto*; Matsuba, Go*; Tominaga, Taiki*; Takata, Shinichi

Microsystem Technologies, 22(1), p.57 - 63, 2016/01

 Times Cited Count:2 Percentile:17.02(Engineering, Electrical & Electronic)

We studied the structural formation process of polyacrylonitrile (PAN) gelation in a wide-spatial scale with the small and wide angle neutron scattering in MLF, J-PARC. In micron-scale structure, light transmittance and gelation time were evaluated. The presence of water in the mixed solvent accelerated the phase separation and gelation. In the opaque-gel case, we observed the nanometer-scaled correlation of crystalline cross-linking points and smooth boundary of two micron-scaled phases due to liquid-liquid phase separation. The correlation length is independent of the annealing time, then the cross-linking point exists locally and micro-gelation occurs during phase separation. By contrast, in the transparent-gel case, the correlation length was found to increase throughout the gelation process, and the entanglements of the polymer chains play a role similar to that of cross-linking points.

Journal Articles

Recent progress in the energy recovery linac project in Japan

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.

Journal Articles

Design of a 500kV electron gun for ERL light source at KEK

Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Kobayashi, Masanori*; Muto, Toshiya*; Matsuba, Shunya*; Sakanaka, Shogo*; Sato, Kotaro*; Saito, Yoshio*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.860 - 862, 2009/08

A newly 500 kV electron gun (2nd - 500 kV gun) for an ERL light source is designed at KEK. A new concept and state of-the-art technologies of vacuum system, ceramic insulators, high voltage power supply, photocathode and preparation system will be employed. The details are described in this report.

Journal Articles

Improvement of poly(vinyl alcohol) properties by the addition of magnesium nitrate

Kubo, Junichi*; Rahman, N.*; Takahashi, Nobuaki; Kawai, Takahiko*; Matsuba, Go*; Nishida, Koji*; Kanaya, Toshiji*; Yamamoto, Masahide*

Journal of Applied Polymer Science, 112(3), p.1647 - 1652, 2009/05

 Times Cited Count:24 Percentile:63.43(Polymer Science)

Aiming at improvement of mechanical and dielectric properties of poly(vinyl alcohol) (PVA) we prepared composites of PVA and magnesium nitrate. It was found that the composites were very soft and rubber-like, and the glass transition temperature decreased with increasing the salt concentration. Wide-angle X-ray diffraction and small-angle X-ray scattering revealed that the crystallites of PVA were destroyed by the additive and it was a cause of the softening.

Journal Articles

Quantum beam studies on polymer crystallization under flow

Kanaya, Toshiji; Matsuba, Go*; Ogino, Yoshiko*; Takahashi, Nobuaki; Nishida, Koji*

Polymer Journal, 39(11), p.1085 - 1097, 2007/11

 Times Cited Count:0 Percentile:0.01(Polymer Science)

One of the longstanding issues in polymer science is crystallization of polymers under flow, especially formation of the so-called shish-kebab. Recent progress in quantum beam technology shed light on the substantial nature in the shish-kebab formation. In this paper we review our recent experiments on polymer crystallization under flow using time-resolved depolarized light scattering, small-angle and wide-angle X-ray scattering and small-angle neutron scattering in a wide spatial scale from 0.1 nm to several tens m. These studies revealed that the shish-kebab formation is governed by a competition between the crystallization rate and the chain relaxation rate.

Journal Articles

Crystallization of isotactic polypropylene under shear flow observed in a wide spatial scale

Ogino, Yoshiko*; Fukushima, Hajime*; Takahashi, Nobuaki; Matsuba, Go*; Nishida, Koji*; Kanaya, Toshiji*

Macromolecules, 39(22), p.7617 - 7625, 2006/10

 Times Cited Count:77 Percentile:89.92(Polymer Science)

We studied crystallization process of isotactic polypropylene (iPP) under shear flow as a function of shear rate using time-resolved wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), depolarized light scattering (DPLS) and polarized optical microscope (POM) to elucidate the formation mechanism of the so-called shish-kebab structure in a wide spatial scale from 0.1 nm to several tens micro-m. In the time-resolved DPLS, SAXS and WAXS measurements we observed the formation processes of the shish-like structure, the kebab structure and the crystalline lattice (mostly in the kebab), respectively, and found that there were critical shear rates for the anisotropic structure formation in the DPLS, SAXS and WAXS measurements. The values are very close each other, suggesting the anisotropic structure formations in both of the shish and the kebab are dominated by a common origin. Furthermore, comparing the onset times of intensities in DPLS, SAXS and WAXS, we found that the onset of DPLS intensity is the most accelerated by the shear among the three. On the basis of the observations, we propose a possible mechanism for the shish-kebab structure.

Journal Articles

Neutron spin-echo studies on crossover from single chain motion to collective dynamics

Kanaya, Toshiji; Takahashi, Nobuaki; Inoue, Rintaro*; Matsuba, Go*; Nishida, Koji*; Nagao, Michihiro*

ISSP Activity Report on Neutron scattering Research; Experimental Reports (CD-ROM), 13, 1 Pages, 2006/00

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