• Bulletin of the Korean Chemical Society
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• v.3 no.3
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• pp.83-88
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• 1982

Viscosity and zeta-potential of 11.0 wt. % aqueous bentonite suspension containing various electrolytes and hydrogen-ion concentration were measured by using a Couette type automatic rotational viscometer and Zeta Meter, respectively. The effects of pH and elcctrolytes on the rheological properties of the suspension were investigated. A system, which has a large zeta-potcntial, has a small intrinsic relaxation time ${\beta}$ and a small intrinsic shear modulus $1/{\alpha}$ in the Ree-Eyring generalized viscosity equation, i.e., such a system has a small viscosity value, since ${\eta}={\beta}/{\alpha}$. In general, a stable suspension system has large zeta-potential. The stability condition of clay-water suspension can be estimated by viscometric method since stable suspension generally has small viscosity. The correlation between the stability, viscosity and zeta-potential has been explained by the Ree-Eyring theory of viscous flow.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1505-1509
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• 2004

The suspension of hardened red blood cells (RBCs) differs from the suspension of normal RBCs with respect to their rheological behavior. The deformability of normal and hardened RBCs (obtained by heating blood at $49^{\circ}C$ or by incubating RBCs in a solution of hydrogen peroxide) was measured with a slit diffractometer and RBC suspension viscosity was measured with a rotational viscometer. The peroxide-treated RBCs showed a significant decrease of the deformability and their suspension viscosity increased over a range of shear rates. The suspension viscosity of the heated RBCs, however, where the deformability is even lower than that of the peroxide-treated RBCs, was slightly higher than that of the normal RBC suspension in the high shear rates. The present study found that not all rigid cells cause an increase of blood viscosity at high shear rate, and therefore that decreased membrane deformability is not predictive of high-shear blood viscosity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.194-200
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• 2009

Suspension of a single solid particle in a channel flow with a constant pressure gradient is studied numerically. The interaction of a circular particle with a surrounding Newtonian fluid is formulated using a combined formulation. Numerical results are presented using two dimensionless variables: the sedimentation Reynolds number and the generalized Froude number. From the present results, it has been shown that a solid particle is suspended at a smaller generalized Froude number as the viscosity of the surrounding fluid increases. The time taken for equilibrium position is found to be smaller as fluid viscosity increases when both : the sedimentation Reynolds number and the generalized Froude number are the same while, at the same situation, the dimensionless time taken for equilibrium position is to be nearly the same regardless of fluid viscosity when a dimensionless time variable is introduced

• YAKHAK HOEJI
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• v.35 no.4
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• pp.277-282
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• 1991

Rheological, colloidal and micromeritical properties were followed to investigate aging mechanisms of hydrous aluminum oxide suspension using Zeta-meter systems, BET adsorption apparatus, Master sizer and electronmicroscope. The results indicate that hydrous aluminum oxide suspension revealed plastic flow with thixotropy. The viscosity, thixotropy and yield value were increased with increasing concentration. During aging process, the viscosity and thixotropic index were increased by an addition of glycerin, however, sorbitol stabilized aging process of the suspension being accompanied with growth of particle size and reduction in specific surface area, pore area and pore volume, and consistency. Diminution of adsorptive power of the particles was also protected by addition of sorbitol to hydrous aluminum oxide suspension. From these results, one of aging mechanism of hydrous aluminum oxide suspension assumed growth and/or crystallization of colloidal particles in aqueous suspension.

• Carbon letters
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• v.14 no.1
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• pp.45-50
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• 2013

Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

• Korea-Australia Rheology Journal
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• v.15 no.4
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• pp.179-185
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• 2003

Associating polymers act as flocculants in colloidal suspensions, because the hydrophobic groups (hydrophobes) can adsorb onto particle surfaces and create intermolecular cross-linking. The steady-shear viscosity and dynamic viscoelasticity were measured for suspensions flocculated by multichain bridging of associating polymers. The effects of surfactant on the suspension rheology are studied in relation to the bridging conformation. The surfactant molecule behaves as a displacer and the polymer chains are forced to desorb from the particle surfaces. The overall effect of surfactant is the reduction of suspension viscosity. However, the additions of a small amount of surfactant to suspensions, in which the degree of bridging is low, cause a viscosity increase, although the number of chains forming one bridge is decreased by the forced desorption of associating polymer. Since the polymer chains desorbed from one bridge can form another bridge between bare particles, the bridging density over the system is increased. Therefore, the surfactant adsorption leads to a viscosity increase. The surfactant influences the viscosity in two opposing ways depending on the degree of bridging.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.302-310
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• 1990

A study has been made of the Korean bentonite aqueous suspension contrast with American bentonite by means of XRD IR swelling, gel formation and rheogram at various conditions such as concentration, temperature and pH. The Korean bentonite was identified as montmorillonite clay containig a small proprotion of crystoballite and mordenite, and its swelling power were acceptable for requirements of Korean pharmacopeia regulations though its values were not satisfied. Korean bentonite swelled to 10 times and American one did to 15 times compared to its bulkiness of powder. The rheogram of Korean bentonite suspension reveals bulged pseudoplatic flow with yield value at higher concentration and pseudoplastic flow without yield value at lower concentration. The higher the concentration, the greater were the apparent viscosity and hysteresis loop. Korean bentonite suspension showed insignificant temperature dependence on both apparent viscosity and hysteresis loop and it was more temperature dependent on viscosity but less on hysteresis loop than those of American sample. The pH dependence was so high on viscosity that apparent minimum value was near pH 7 and maximum value at pH 3 or 7. The hysteresis loop appeared minimum over the pH range 5-7 and maximum near pH 3 or 11. The Korean bentonite was inferior to the American bentonite in swelling volume, gel formation, thioxotropy, however, it would be possible to improve the quality of Korean bentonite by developing the method of purification for bentonite clay.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.128-134
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• 1999

Rheological characterization was examined for two different types of magenetic particle (rod-like $\gamma$-$Fe_{2}O_{3}$, $CrO_2$ )suspension in this study. The measured suspension viscosity (viscosity vs. concentration or shear rate) is used to obtain the dependence of viscous energy dissipation on the microstructural states of magnetic particle dispersions as well as the microstructural shape effects which are related to magnetic particle orientation. The empirical formulas from mean field theory and the Mooney equation are used to relate suspension viscosity to particle concentration. Intrinsic viscosities of these two different types of rod-like magnetic particle suspensions are found to exceed the prediction of hydrodynamic theory for dilute suspensions and support the existence of flocs containing significant amounts of immobilized suspending medium due to native attraction forces among particles in the microstructures.

• Korea-Australia Rheology Journal
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• v.12 no.1
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• pp.77-81
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• 2000

Rheological behavior of thermoset/thermoplastic blends of epoxy/polyethersulphone (PES) was monitored during curing of the epoxy resin. During the isothermal curing of the mixture, a fluctuation in viscosity just before the abrupt viscosity increase was observed. This fluctuation is found to be due to the phase separation of PES from the matrix epoxy resin during the curing. The experimentally observed viscosity fluctuation is simulated with a simple two phase suspension model in terms of the increase in domain size. The viscosity profiles obtained experimentally at different isothermal curing temperatures are in good agreement with the predictions from the simple model taking into account the viscosity change due to the growth of PES domain and the network formation of the epoxy matrix.

• Korean Journal of Food Science and Technology
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• v.38 no.3
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• pp.444-447
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• 2006

Yam powders were prepared by freeze, fan, hot-air, and coal-heat drying. The viscosities of their suspensions and supernatants and the viscosity changes with addition of sugar, salt, and citric acid were investigated. Viscosity (43 mPa s) of 7.5% suspension of fan-dried yam powder was lower than that of freeze dried yam (58.1 mPa s), but much higher than that of the conventional, hot-air dried yam (17.2 mP s). Coal-heat dried yam had a viscosity of only 4.5 mPa s. The viscosity was related to the protein denaturation induced by heat and acid. Addition of sugar to yam powder increased the viscosity of the suspension but no changes were evident with salt addition. Viscosities decreased when 0.5% citric acid was added (pH 3.4-3.5).