Nihon Reoroji Gakkaishi
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
Volume 21 , Issue 1
Showing 1-7 articles out of 7 articles from the selected issue
  • Takayoshi MATSUMOTO, Hirofumi ZENKOH
    1993 Volume 21 Issue 1 Pages 5-10
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    Structure and molecular mobility of complexes between carboxymethylpolysaccharides (carboxymethylcellulose and carboxymethylchitin) and alkaline-earth metal ions in aqueous systems were studied by means of dynamic viscoelasticity, SAXS and NMR measurements.
    The frequency-dependent curves of the dynamic modulus measured with a cone-plate rheometer shift to a longer time-scale region with complex formation and can be superposed to a master curve by only a horizontal shift. This means that the relaxation times lengthen by complexation and that the complexation is an intramolecular rather than an intermolecular process. The SAXS and NMR measurements revealed that the site for complexation is a cavity between the carboxyl group and the hydroxy group attached to the neighbouring residue. A new molecular model for complexation was presented.
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  • Hogyu YOON, Kiyohisa TAKAHASHI, Kazuhisa HARAKAWA
    1993 Volume 21 Issue 1 Pages 11-17
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    Unidirectional carbon fiber (CF)/poly(ether-ether-ketone) (PEEK) composite was manufactured from the commingled yarns composed of CF and PEEK filaments (this composite is named 'commingled composite'). The thermal expansion coefficient (TEC) of the commingled composite was measured and compared with that of CF/PEEK unidirectional composite made of prepreg sheets (this composite is named 'prepreg composite'). The minimum value of TEC's parallel to the fiber direction was observed at around 150°C for both specimens which were not thermally treated. This minimum disappeared after the thermal treatment at 230°C for 30 minutes or the repeating measurements (0°C→230°C, 0°C→230°C,.........). While the TEC of the prepreg composite was almost independent of temperature, that of the commingled composite showed a remarkable decrease at temperatures above the glass transition temperature (Tg) of PEEK. This could be interpreted in terms of the orientation distribution of carbon fibers in the commingled composite. The differerence of longitudinal TEC's between heating and cooling experiments was attributable to the temperature difference between the surface and the inner parts of the specimen. The TEC's transverse to the fiber direction were scarcely influenced by the thermal history. The TEC's increased slowly below 100°C and increased rapidly above 100°C with increasing temperature. Theoretical predictions based on the extended equivalent inclusion method and on the classical lamination theory exhibited good agreement with experimental data. However, it could not be predicted that the TEC's parallel to the fiber direction were depressed at around 30°C. The cause of this discrepancy was supposed due to the temperature dependence of TEC's of the carbon fiber itself.
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  • Takayoshi MATSUMOTO
    1993 Volume 21 Issue 1 Pages 18-22
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    The relationship between sol-gel transition and bound water in bilayer aqueous systems of egg lecithin (EL) was studied by means of rheological, NMR and dielectric measurements. The viscosity and rigidity of the systems increase very sharply at the critical gel concentration c*, and the reciprocal value of the spin-lattice relaxation time of the water proton, T1-1, which is proportional to the correlation time of molecular motion, also increases sharply at c*. This means that the bound water is strongly related to the sol-gel transition of the bilayer aqueous systems of EL. It was confirmed by the dielectric measurements that there were three types of bound water whose characteristic dielectric relaxation times are 2.0×10-8s, 2.3×10-9s and 2.5×10-10s.
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  • Toshikatsu KOBAYASHI, Hiroyuki KAGEYAMA, Shouji IKEDA
    1993 Volume 21 Issue 1 Pages 23-28
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    Pigment dispersion in acid-neutralized water soluble acrylic resins which have both acidic and basic functional groups was studied. The dispersibility was evaluated by the gloss and the yield value of the pastes.
    As for the dispersion of a positively charged pigment, an excellent dispersibility of the pigment was obtained by the resin adsorption through electrostatic interaction between positive charge of the pigment and negative charge of the resins when the acid strength of the resin was higher than that of the neutralizing acid.
    On the other hand, when the acid strength of the neutralizing acid was higher or a negatively charged pigment was used, no effect on the introduction of the acidic functional group to the resins was observed.
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  • Yoshio SHIRASAKI, Tetsuya TATEISHI, Kazuhiro SHIMOYAMA
    1993 Volume 21 Issue 1 Pages 29-32
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    The purpose of this study was to investigate the mechanical properties of resin and porcelain teeth. The static tests were performed with an Instron-type universal testing machine. The dynamic stiffness and tan δ were measured by using a viscoelastic spectrometer. The impact tests were carried out with a drop weigh impact testing apparatus.
    Following results were obtained: 1) The fracture load, ultimate strength, absorbed energy and deformation in the static tests were larger for the resin teeth than for the porcelain teeth. However, the elastic modulus was larger for the porcelain teeth. 2) The stiffness measured dynamically was larger for the porcelain teeth than for the resin teeth. The tan δ was larger for the resin teeth. 3) The imapct tests showed that the absorbed energy and deformation were larger for the resin teeth, while the acceleration peak value was larger for the porcelain teeth.
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  • Noriyasu MORI, Takumi KAIGE, Kiyoji NAKAMURA
    1993 Volume 21 Issue 1 Pages 33-40
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    The unsteady viscoelastic flow generated by the sudden application of a constant flow rate is experimentally examined for an abrupt contraction and a tapered one with a rectangular cross-section. The velocity change with time is measured with a L. D. V. for a 1.0 wt% aqueous solution of polyacrylamide. The gentle overshoot in the centerline velocity, which may be due to the effect of extensional flow, is observed from the vicinity of the entrance of a small slit to the downstream far from the entrance. Furthermore it is found that the flow in the entrance region finally reaches the anomalous threedimensional flow with a dual peak form of the velocity profile.
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  • Keiko AMAKI, Tomiichi HASEGAWA, Masaaki KONNO
    1993 Volume 21 Issue 1 Pages 41-45
    Published: March 15, 1993
    Released: November 20, 2012
    JOURNALS FREE ACCESS
    The effect of fluid force on detergency has been experimentally investigated. More than one hundred wires of 50 μm in diameter, as a model of two dimensional soil, were set so as to adhere to a bottom flat plate of a two dimensional channel. The aqueous solution of surfactant and the dilute aqueous solution of polymer were made to flow through the channel and the pressure drop caused by the wires was measured. The drag and the drag coefficient(CD) of one wire were estimated with the pressure drop by the use of the law of momentum. The following results are obtained. For all solutions used, the drag increases and the drag coefficient decreases with an increase in the Rey-nolds number based on the wire diameter taken as the characteristic reference length. The solution of LAS, one of familiar anionic surfactants, gives CD values lower than the pure water, and the difference becomes marked as the concentration of the solution increases. A nonionic surfactant solution, AE 1.0%, shows a time dependent character it provides about half of the coresponding CD value of water within a day since the solution was produced, while it gives nearly the same as that of water after 4 days have passed. The CD for dilute solution of polymer (PEO 20 ppm) in water is higher than those for water and surfactant solutions. Viscosities of the solutions tested were Newtonian and the magnitudes are in the same order for all three solutions. These results suggest that the variation of CD observed for the three solutions is not directly related to the solution viscosity but probably to other properties such as elastic force.
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