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Volume 38 (2010)
- Issue 4_5 Pages 157-
- Issue 3 Pages 109-
- Issue 2 Pages 61-
- Issue 1 Pages 1-
Volume 38, Issue 4_5
(combined issue)
Displaying 1-10 of 10 articles from this issue
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AWARD LECTURE ARTICLES
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Hiromoto Usui2010 Volume 38 Issue 4_5 Pages 157-166
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSA thixotropy model was developed for the suspensions which have particle size distribution both for the case of spherical and non-spherical particles. The number of primary particles contained in a cluster was selected as the thixotropy parameter. This model is applicable for highly loaded agglomerative slurries. The inter-particle bonding energy is the key parameter, which can be determined by the apparent viscosity measurement of slurry. As the industrial application, this suspension model was applied for latex coagulation process to predict the cluster size of latex. Also, the spin coating process of PMMA particle suspension was investigated to control the optical characteristics of coated film. The validity of the proposed suspension model was confirmed by comparing the model predictions with the experimental data obtained for several industrial application processes.View full abstractDownload PDF (4133K)
AWARD LECTURE ARTICLES
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Takatsune Narumi2010 Volume 38 Issue 4_5 Pages 167-173
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSFluidity changes of various complex fluids corresponding to those structure changes have been investigated. Peculiar responses of the fluids were mainly examined in transient flows. Electro-rheological characteristics of liquid crystals were systematically clarified and relatively simple models were developed for both steady and oscillatory flows. Flow induced unstable structure generated with a liquid crystalline polymer were examined in slit flows with a corner. The characteristics of the unstable texture were clarified and the stability of the structure was controlled with the channel design. Typical transient responses of concentrated suspensions due to structure rearrangements of particles have been clarified in re-started flows and LAOS flows. It was found in LAOS experiments that the response waveforms consisted of the transient response after each reversal in the shearing direction, followed by purely viscous behavior. The characteristic strain for the microstructural rearrangement was found to be essentially independent of the oscillation frequency, and showed good agreement with the corresponding characteristic strain obtained from the re-started flows.View full abstractDownload PDF (1492K)
AWARD LECTURE ARTICLES
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Yasuharu Nakagawa, Takanobu Ueda2010 Volume 38 Issue 4_5 Pages 175-180
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSEstablishing manufacturing processes, skin effects, texture and preventing problems with stability are all integral in the development and manufacture of cosmetics. The aim of this study was to evaluate the usefulness of rheological measurement in these areas of cosmetic production. Rheological measurement was applied at various stages during the development and manufacture of a bath milk, a skin care product and a make-up removing milk. The results of the study showed a significant correlation between the rheological measurement results and that of microscopic observations, sensory evaluations and stability tests. In conclusion, this study proved that rheology is useful in the development and manufacture of cosmetics.View full abstractDownload PDF (1295K)
AWARD LECTURE ARTICLES
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Yang Ho Na2010 Volume 38 Issue 4_5 Pages 181-186
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSThe dynamic aspects and the structural characteristics of double network (DN) gels and polymer blend electrorheological (ER) fluids have been investigated. The polymer hydrogels with the DN structure that consisted of the electrolyte gel and the neutral gel have been synthesized. The DN gels exhibited 0.1-1 MPa of elastic modulus, 60 MPa of compressive fracture stress, and 2500 J/m2 of facture energy. The structural characteristics and dynamics of the DN gels with high strength were examined. Moreover, the necking phenomenon, which was first observed in gel systems was shown. The model for anomalously high fracture energy of DN gels was also proposed, showing how the fracture energy was effectively dissipated. About the ER fluids, the structure observation and the stress measurement of immiscible polymer blends under the flow and the electric field have been carried out. The morphology change, instability, and viscoelasticity of the polymer blend ER fluids were examined. I demonstrated that detailed observations could be made by using a confocal scanning laser microscope (CSLM), and investigated the relation between the structure and the shear stress in the evolution process from droplet-discpersed state to network one. I have also measured the response of shear stress to ac electric fields, and found a characteristic mode under steady shear flow in the droplet dispersed phase. The origin of the mode was explained on the basis of the Maffettone-Minale model.View full abstractDownload PDF (1409K)
ORIGINAL ARTICLES
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Quan Chen, Akiko Uno, Yumi Matsumiya, Hiroshi Watanabe2011 Volume 38 Issue 4_5 Pages 187-193
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSFor monodisperse linear polymers, the steady state recoverable compliance J characterizing the terminal relaxation intensity/mode distribution is known to be (approximately) proportional to the molecular weight M in the light to moderately entangled regime, i.e., for M between the entanglement molecular weight Me and the characteristic molecular weight Mc' defined for J (Mc' = 4Me - 6Me). However, for those lightly to moderately entangled polymers, the so-called glassy relaxation and Rouse fluctuation processes have a non-negligible contribution to the complex modulus G* even in the terminal regime and thus to J. In other words, the G* and J data of those polymers do not exclusively reflect the entanglement relaxation behavior of those polymers. For a test of this behavior, linear viscoelastic data were examined for entangled linear polystyrene (PS) and poly(p-tert-butyl styrene) (PtBS) in a wide range of M. The contribution of the glassy and Rouse fluctuation modes were subtracted from the G* data to evaluate the modulus Gent* exclusively reflecting the entanglement relaxation. It turned out that the terminal mode distribution of Gent* and the corresponding compliance Jent were rather insensitive to M even for M < Mc' and close to those of well entangled high-M polymers, in particular for the case of PS. This result provides us with a clue for discussing the onset of entanglement.View full abstractDownload PDF (1033K) -
Ken Morishima, Tadashi Inoue2010 Volume 38 Issue 4_5 Pages 195-200
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSAn apparatus for dynamic viscoelasticity measurements was developed using laser particle tracking method (LPT). LPT measures the position of micron-sized probe particles embedded in the material. The power spectrum density (PSD) is calculated from the displacement of the probe particle due to Brownian motion, and then the complex modulus is determined from PSD. This method is useful for studying viscoelastic properties at high frequency region in addition to investigating local viscoelastic properties of materials. The apparatus was calibrated with pure water and ethyleneglycol. The complex shear modulus for aqueous solution of wormlike micelles in high frequency regime was measured. The complex shear modulus obtained by LPT showed a good agreement with the results obtained by a conventional rheometer and the flow birefringence measurement, indicating the reliability of the apparatus.View full abstractDownload PDF (1543K) -
Mohammad-Mehdi Hedayat, Mohammad-Hossein Borghei, Abbas Fakhari, Kayva ...2011 Volume 38 Issue 4_5 Pages 201-207
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSThe effect of a fluid's strain-hardening behavior is investigated on the flow kinematics inside a two-dimensional square cavity. A special form of the Generalized Newtonian Fluid model (referred to as Pinho model) is used in which the strain-hardening behavior of the fluid is accounted for by incorporating a strain-rate term in the power-law viscosity function. Use will be made of the incompressible Lattice Boltzmann Model (LBM) to numerically solve the governing equations. Converged results could be obtained at Reynolds numbers up to Re = 5000 showing that the strain-hardening behavior has indeed a strong effect on the flow kinematics. The size of the corner vortices is predicted to decrease by an increase in the strain-hardening behavior of the fluid. It is also predicted that the streamline pattern becomes quite symmetric by an increase in the fluid's strain-hardening behavior.View full abstractDownload PDF (2754K) -
Saori Kikuchi, Takashi Saeki, Masahiro Ishida, Kazuaki Tabata, Kohzo O ...2010 Volume 38 Issue 4_5 Pages 209-214
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSWe have developed a new production method for silica sols using a Y-shaped reactor. Diluted sodium silicate and sulfuric acid were forced to collide against each other at the intersection of the reactor. Silica sols with the appropriate viscosity produced by this method could be used as waste water treatment agents and retention aids for papermaking. In this study, the gelation process of silica sols was considered by dynamic viscoelastic measurements. Furthermore, we observed directly observed the gel surface using a scanning probe microscope (SPM). From the results, the onset time of gelling was strongly affected by both the concentration of SiO2 and the excessive rate of sulfuric acid. The gel surface structure produced with different conditions was also characterized. It was found that larger coalescence of silica particles presented in gels and the coalescence rate depended on the excessive rate of sulfuric acid.View full abstractDownload PDF (1544K) -
Akiomi Ushida, Tomiichi Hasegawa, Shouta Kudou, Masato Kawami, Hiroshi ...2010 Volume 38 Issue 4_5 Pages 215-221
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSJet thrusts of several kinds of liquids issuing through small orifices were measured and compared with the predictions from numerical simulations of the Navier-Stokes equations. Reasonable agreements for so-called Newtonian fluids were obtained between the experimental and predicted thrusts for capillaries and orifices with openings of the order of 100 μm size, but the experimental thrusts were found to be below the predictions for orifices of the order of 10 μm. It was suggested that water and glycerol solutions have an elastic property for elongational flows passing through small orifices. As to surfactant aqueous solutions, cationic surfactant(BC) and non-ionic surfactant(AE(23)) provided thrusts lower than those of water, but anionic surfactant(LAS) showed almost the same thrusts as water. Also, lower thrusts were measured for dilute polymer aqueous solutions of PEO(18). A mean elastic stress for the tested liquids was evaluated by using the measured thrusts, and discussion was made on the idea that flows near the wall are affected by an interaction between anions on the surface of orifice and charged molecules of surfactants.View full abstractDownload PDF (1397K) -
Takeaki Tsuda2010 Volume 38 Issue 4_5 Pages 223-230
Published: February 15, 2011
Released on J-STAGE: February 13, 2011
JOURNAL FREE ACCESSOne-dimensional flow equations were derived for non-Newtonian fluids in slot coating and a simple numerical method was proposed to solve the equations. We investigated non-Newtonian effects on coating performance and coating quality in slot coating. In some cases, computational results and experimental data were compared and both agreed well. A series of numerical computations showed that the one-dimensional approach can describe non-Newtonian flow under lips in a few minutes and that a pressure field equation proposed by Higgins can determine the location of an upstream meniscus. Moreover, it was found that the non-Newtonian characteristics of coating liquids affect both coating performance and coating quality. Because each non-Newtonian effect is quite different, we should optimize the conditions of slot coating and die geometries according to the target problem.View full abstractDownload PDF (1372K)
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