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Volume 18 (1990)
- Issue 4 Pages 151-
- Issue 3 Pages 95-
- Issue 2 Pages 59-
- Issue 1 Pages 5-
Volume 18, Issue 3
Displaying 1-8 of 8 articles from this issue
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Takayoshi MATSUMOTO1990 Volume 18 Issue 3 Pages 95-104
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSInteraction between amphiphiles and water molecules in micelle or bilayer structure has been investigated using aqueous colloids of various amphilphies. The water molecule is not necessarily bound in the fully developed micelle or bilayer (rod-like or lamella) structure which induces the high viscosity or high rigidity of the colloidal system. On the other hand, the water molecule is bound in the micelle colloids of amphoteric amphiphiles or amphiphiles whose molecular assembly creates a realtively strong electrostatic field.
Micelle structure of a nonionic amphiphile (n-dodecyl octa (oxyethylene glycol) monoether), which has a weak interaction with water molecules, has been investigated. The spherical micelles having a radius of 28-31 Å remain in a wide concentration range from very dilute to ca. 42wt%. In the concentrated colloids in the isotropic (L1) phase, the spherical micelles are arranged in a certain ordered structure, and the isotropic and the ordered phases are likely to coexist. However, even at such a high concentration as 30wt%, the colloid system shows Newtonian flow.
The specific inner surface Os of the spherical micelle in the L1 phase is ca. 0.2Å-1 and this value is approximately twice as large as that of a smooth sphere. Electron density profile is relatively sharp at the interface between the micelle and the medium, regardless of the existence of some bound water. A new micelle model is proposed.View full abstractDownload PDF (1297K) -
Akihiko KOIWAI, Takaaki MATSUOKA, Hideroh TAKAHASHI, Yorihide KUBOTA, ...1990 Volume 18 Issue 3 Pages 105-110
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSA rheometer with a wide-gap Couette geometry was developed to study reactive kinetics and rheological properties of the reactive polyurethane systems for a reaction injection molding (RIM). Viscosity and temperature changes during the adiabatic reactions were measured for three different polyurethane systems which had gelation times of a few seconds. The viscosity and temperature changes during the RIM process were predicted by a simple rheo-kinetic theory using the material parameters determined from the adiabatic measurements.
A one-dimensional heat transfer analysis program of the RIM system was developed and the temperature profile in the urethan plate was calculated by the pre-determined material parameters. A good agreement was obtained between the measured temperature and the calculated one.View full abstractDownload PDF (866K) -
Yasufumi OTSUBO, Koichiro WATANABE1990 Volume 18 Issue 3 Pages 111-116
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe electrorheology (ER) of suspensions of barium titanate particles in a silicone oil was studied in electric fields up to 1kV?mm-1. By the use of an oscillating plate rheometer, the dynamic viscosity was measured at 45 Hz in the sample thickness range of 40-75 μm. The viscosity immediately increases on application of the electric fields and the suspensions change from viscous liquids to gel-like paste with plastic tendency.Significant flow occurs only after a yield stress is exceeded, which increases with the electric field. The addition of a small amount of water leads to an increase of yield stress in a given electric field, but the viscosity in the absence of the electric field is also increased. A surfactant was used to decrease the zero-field viscosity. Because of combination effects of surfactant and water, the suspension with greatly enhanced yield stress and low zero-field viscosity can be prepared. The rapid response of viscosity increase (within 10 ms) suggests that the ER effect is associated with the polarization of molecules adsorbed on the particle surface rather than the motion of the particle itself.View full abstractDownload PDF (876K) -
Hogyu YOON, Kiyohisa TAKAHASHI1990 Volume 18 Issue 3 Pages 117-124
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThermal expansion coefficients (TEC) of composites reinforced with orientation -distributed carbon fibers have been theoretically analyzed. A solution procedure is formulated according to Eshelby's equivalent inclusion method (E. I. M. ) which takes into account the orientation distribution and the interaction of fibers. A procedure based on the lamination theory (L. T. ) is also developed and compared with the E. I. M. TEC are calculated for carbon fiber and glass fiber composites with several types of fiber orientation distribution. The difference between the TEC predicted by the E. I. M. and the L. T. can be attributed to an interaction between fibers in the different laminae which was not considered in L. T. While the E. I. M. is consistent for glass fiber composites, a theoretical contradiction occurs for the prediction of the TEC of composites with orientation-distributed carbon fibers, when the volume fraction of fibers approaches to 100%. In a range of low fiber volume fraction, the difference between the predictions by the E. I. M. and by the L. T. is smaller for carbon fiber composites than for glass fiber composites. And the difference is small compared with errors expected in the measurements. Both of the E. I. M. and the L. T. may be used for the prediction of TEC of composites filled with orientation-distributed carbon fibers in the range of low fiber volume fraction less than about 40%.View full abstractDownload PDF (995K) -
Hideroh TAKAHASHI, Yoshinori INOUE, Satoru YAMAMOTO, Osami KAMIGAITO1990 Volume 18 Issue 3 Pages 125-128
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe flow curves of mixtures of acrylonitrile-styrene copolymers with the same S/AN ratio (70/30) and different molecular weights (SAN-1; Mw=1.88×105, SAN-2; Mw=6.5×104) were measured up to the shear rate of 107 s-1. The second Newtonian and the second non-Newtonian region were observed for SAN-1, SAN-2 and their mixtures (<106 s-1) following the first non-Newtonian region. The viscosity decreased with decrease of molecular weight (increase of SAN-2 content) and the gradient of the flow curve (log viscosity vs. log shear rate) of the mixture became smaller with decrease of molecular weight in the first non-Newtonian region. Flow behavior of the mixture was quite different from that of the immiscible polymer blends. The flow curves of SAN with different molecular weights (≥1.28×105) united into one curve at the shear rates higher than 5×105s-1.View full abstractDownload PDF (553K) -
Toshikazu TAKIGAWA, Toshiro MASUDA1990 Volume 18 Issue 3 Pages 129-132
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSA general model which describes the long time relaxation characteristics of micro-heterogeneous polymer liquids is presented. According to the model, the long time relaxation is originated from the diffusional motion of a molecule under a harmonic potential field in viscous medium. This model qualitatively predicts that non-linear viscoelasticity is observed for relaxation at large strain amplitudes.View full abstractDownload PDF (491K) -
Masahiro KISHINE, Norio NEMOTO, Tadashi INOUE, Kunihiro OSAKI1990 Volume 18 Issue 3 Pages 133-139
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe viscoelasticity and diffusion were studied for solutions of eight polystyrene (PS) samples in dibutyl phthalate (DBP). The molecular weight (M) ranged from 43, 900 to 5, 480, 000 and the concentrations were 13 and 18wt%. The viscosity, η, the steady state compliance, Je0, and the longest relaxation time,τ1 were determined from the dynamic complex modulus G* (ω) or the shear relaxation modulus G (t). The self-diffusion coefficient, Ds, obtained from Forced Rayleigh scattering measurements varied as Ds∝ M-2.5 for M>Me. Here the entanglement molecular weight, Me, was estimated with a formula Me=1.8×104 C-1. At relatively low molecular weights, M<10Me, the product Dsη was approximately constant and close to the prediction of the Rouse model theory. At higher molecular weights, the product Dsη was approximately proportional to M/Me, in qualitative agreement with the prediction of the tube model theory. The quantity DsηJe0/M did not vary much over the whole range of M studied.View full abstractDownload PDF (828K) -
Takayoshi MATSUMOTO, Hirofumi ZENKOH, Tomoyasu KAJI1990 Volume 18 Issue 3 Pages 140-144
Published: September 20, 1990
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDynamic viscoelastic properties of aqueous solutions of sodium alginates and alginate/calcium complex were measured in the presence and in the absence of free-state ions (external salt). The M/G ratios of these alginates are ranging from 0.21 to 0.88. Dynamic modulus G′of the sodium alginates in a low frequency region increases with the addition of the external salt CaCl2 and G′in a high frequency region is almost independent of the concentration of CaCl2.
On the other hand, in the absence of free ions, dynamic modulus of the aqueous solutions of alginates, in which Na ions are substituted partially by Ca ions, increases with increasing calcium content over the measuring frequency region. That is, from a rheological viewpoint, a complex structure between alginate residues and Ca ions works as a heterogeneous relaxation unit having a relatively long relaxation time in the presence of free ions and it works as a crosslinking point in the absence of free ions.View full abstractDownload PDF (660K)
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