Hisanori Ohkita
Keio University
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Publication
Featured researches published by Hisanori Ohkita.
Japanese Journal of Applied Physics | 2005
Hisanori Ohkita; Kayoko Ishibashi; Ryo Tanaka; Akihiro Tagaya; Yasuhiro Koike
We report the anisotropic molecule dopant method for compensating the photoelastic birefringence of polymers. In this method, a rodlike molecule that has a polarizability anisotropy was chosen and doped in a polymer. We demonstrated this method by compensating the negative photoelastic birefringence of poly(methyl methacrylate) and poly(2,2,2-trifluoroethyl methacrylate) at a wavelength of 633 nm. trans-Stilbene and fluorene were selected as the anisotropic molecules. Homogeneous doping with the molecules almost eliminated the photoelastic birefringence of the polymers. We found that the photoelastic birefringence of poly(methyl methacrylate) was compensated by the elastic motion of trans-stilbene in the polymer as determined by the analysis of the infrared absorption spectrum. Furthermore, the orientation distribution function of trans-stilbene in a uniaxially strained PMMA film in a solid glass state was estimated by the investigation of infrared dichroic ratios.
Applied Physics Letters | 2004
Hisanori Ohkita; Yasuyuki Abe; Hiroshi Kojima; Akihiro Tagaya; Yasuhiro Koike
A method for reducing the orientational birefringence of polymers by doping with optically isotropic silica particles is reported. Particles with a diameter of 16 nm were selected and their surface was treated with dimethyldichlorosilane. Doping with 1 wt% of the particles reduced about 15% of the orientational birefringence of polycarbonate and poly(methylmethacrylate) films regardless of the sign and the magnitude of their birefringence. The analysis of the infrared dichroic ratio confirmed an effect in which the particles reduced the orientation of polycarbonate main chains. The effect that caused the reduction of birefringence was named “the orientation-inhibition effect.”
Macromolecules | 2006
Akihiro Tagaya; Hisanori Ohkita; Tomoaki Harada; Kayoko Ishibashi; Yasuhiro Koike
Science | 2003
Akihiro Tagaya; Hisanori Ohkita; Masaki Mukoh; Ryuichi Sakaguchi; Yasuhiro Koike
Macromolecules | 2004
Hisanori Ohkita; and Akihiro Tagaya; Yasuhiro Koike
Applied Physics A | 2005
Hisanori Ohkita; Kayoko Ishibashi; D. Tsurumoto; Akihiro Tagaya; Yasuhiro Koike
Macromolecular Symposia | 2006
Yasuhiro Koike; Keita Yamazaki; Hisanori Ohkita; Akihiro Tagaya
Journal of Materials Science | 2007
Chie Inui; Hiroaki Kura; Tetsuya Sato; Yosuke Tsuge; Seimei Shiratori; Hisanori Ohkita; Akihiro Tagaya; Yasuhiro Koike
Materials Science and Engineering: C | 2006
Akihiro Tagaya; Hisanori Ohkita; Yasuhiro Koike
Organic and Polymeric Materials and Devices | 2003
Hisanori Ohkita; Masaki Mukoh; Akihiro Tagaya; Yasuhiro Koike