• Title/Summary/Keyword: viscosity increase

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Effect of surfactant adsorption on the rheology of suspensions flocculated by associating polymers

  • Otsubo, Yasufumi;Horigome, Misao
    • 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.

On Energy Saving and Quality Improvement of Food Process (1). Applications of Hotwire Monitoring System for Food Biotechnology (식품공정의 에너지 절감과 품질향상에 관한 연구(1). 세선 가열법의 식품 생물공학에의 응용)

  • 허종화;크라우
    • KSBB Journal
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    • v.5 no.4
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    • pp.403-410
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    • 1990
  • Application of the Rheocatch Hotwire Monitoring System for food biotechnology process was evaluated. The growth of microogranism, E coli (JM 83 and Sigma) and Corynesccfertun glutamicum, were monitored. in the fermentor. The cell growth could not be detected the temperature differences between the hotwire and samples($\Delta$T) as indicated by the monitoring system during the fermentation processes. The cell concentration of less than 2g/dl was not sufficient to generate the measurable temperature difference in the fermentor. In order to calibrate the Rheocatch Monitoring System, the temperature difference as a function of solute concentration (microbial cells, sodium cholide, sucrose and dextran) was studied. The relationship between $\Delta$T and the concentration of microbial cells, sucrose and dextran can be expressed in a power series. Further studied with dextran indicated that viscosity and/or kinematic viscosity increase exponentially with an increase in $\Delta$T This is regardless of the concentration and molecular weight of dextran. $\Delta$T linearly increases with the logarithm of molecular weight, while the logarithm of viscosity and the logarithm of kinematic viscosity increase with the logarithm of molecular weight.

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CHANGE OF BLOOD VISCOSITY AND DEFORMABILITY IN ORAL SQUAMOUS CELL CARCINOMA PATIENTS (구강편평세포암종 환자에서의 혈액 점도와 혈액 변형성 변화에 대한 연구)

  • Yun, Pil-Young;Myoung, Hoon;Lee, Jong-Ho;Choung, Pill-Hoon;Kim, Myung-Jin
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.30 no.3
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    • pp.181-185
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    • 2004
  • Malignant tumor have hypoxic cell fraction, which makes radio-resistant and hypoxia in tumor is a result from the blood flow decrease caused by increase in blood flow resistance. Blood viscosity increase is major factor of increased blood flow resistance and it could be attributed to the decrease in blood deformability index. For the evaluation of the change of blood viscosity and blood deformability in oral squamous cell carcinoma, we perform the test of the change of those factors between the normal control group and oral squamous cell carcinoma cell patient group. Relative viscosity measured against distilled water was $5.25{\pm}0.14$ for normal control group, and $5.78{\pm}0.26$ for the SCC patient group and there was statistical significance between the groups. However, there was no significant difference between the groups in blood viscosity between the groups by tumor size (T1+T2 vs T3+T4). Also, there was no significant difference between the normal control group and SCC patient group in blood deformability index and between the groups by tumor size (T1+T2 vs T3+T4). Increase in blood viscosity was confirmed with this study and it can be postulated that modification blood viscosity might contribute to decrease of hypoxia fraction in oral squamous cell carcinoma, thus improve the effect of radiotherapy and it can be assumed that the main factor of blood viscosity increase is not decrease of blood deformability in oral squamous cell carcinoma.

The beating effect of high crystalized nonwood fibers treated with low-molecular weighted waste celulase in the papermaking processes (Cellulase생산공정중 발생되는 저분자량 분포도의 폐효소류 처리가 고결정화된 배목재 섬유소의 고해에 미치는 영향)

  • 김병현;신종순;강영립;박병권;이성구
    • Journal of the Korean Graphic Arts Communication Society
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    • v.18 no.1
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    • pp.121-139
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    • 2000
  • This study is to test the possibility of applying the low-molecular weighted waste cellulase, which is produced in the process of cellulase production, to paper making. After experimenting on high-crystallized non-wood fibers with beating catalyst. I got the result that the condition for the optimal effect is temperature 40~6$0^{\circ}C$, the time 90min to 120min, pH 5.0 to 6.0, the enzyme contents 0.3% and that the effect of beating such as slight reduction of fiver viscosity, increase of water retention value(WRV) and shortening of fiber length was increased with waste cellulase. Through this process, the density, folding endurance, tensile strength and burst strength of paper was remarkably increased, which is inferred to result from the increased flexibility of fiber by individual characteristics of non-wood fiber, which was high-crystallized by penetrated low-molecular weight cellulases in the fiber.

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Experimental Study on Thermal Conductivity and Viscosity of Grouts for Backfilling Ground Heat Exchanger (수직 밀폐형 자중 열교환기용 뒤채움재의 열전도 및 점도특성 연구)

  • Choi, Hang-Seok;Lee, Chul-Ho;Gil, Hu-Jeong;Choi, Hyo-Pum;Woo, Sang-Baik
    • New & Renewable Energy
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    • v.3 no.4
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    • pp.38-46
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    • 2007
  • In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than the case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

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Comparison of Bacterial Cellulose Production in a Jar Fermentor Between Acetobacter xylinum BPR2001 and its Mutant, Acetan-Nonproducing Strain EP1

  • BAE SANG OK;SUGANO YASUSHI;SHODA MAKOTO
    • Journal of Microbiology and Biotechnology
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    • v.15 no.2
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    • pp.247-253
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    • 2005
  • The bacterial cellulose (BC) production by a wild­strain Acetobacter xylinum BPR2001 and that by its acetan­nonproducing mutant, EPI, were compared in a jar fermentor. EPI produced about $28\%$ less BC than the wild-strain. The apparent difference in the cultivation of the two strains was the viscosity increase in the culture broth that was closely associated with acetan production. Increasing the viscosity of the culture broth of EPI by adding agar led to the formation of relatively small and uniform BC pellets, and BC production consequently became two-fold higher than that in the absence of agar and was almost equal to that by BPR2001. Therefore, acetan has an important role in BC production by inducing physical changes in the culture broth of the wild-type strain.

Effects of Hydroxy Silicone Oil on Insulation Properties of Silicone Rubber(1) (Hydroxy Silicone Oil이 실리콘 고무의 절연특성에 미치는 영향(1))

  • 강동필;박효열;안명상;이웅재;이후범;오세호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.11
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    • pp.1001-1007
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    • 2003
  • The silicone fluids have been generally used as processing agent in silicone rubber(SIR) compounding. The addition of hydroxy silicone (HS) fluids to SIR for insulator housing material is required to meet the good electrical performance and the good processability. In this study, SIR with HS fluids was evaluated to investigate how the kinds of them affect insulation properties. The contact angle of the virgin sample of 40-HS SIR was low and its recovery rate was also slow. The recovery rate of 50-HS SIR was the highest being decreased with the viscosity increase of HS fluids. The tracking resistances and the corona aging resistance of 70-HS SIR and 1,040-HS SIR were excellent Tracking resistance depended largely on heat resistance of silicone fluids. But arc resistance didn't depend merely on the kind of silicone fluids.

An Experimental Study on Breakup Mode of Epoxy Paint Discharging from a Fan Spray Nozzle (선형분무노즐로부터 분무되는 에폭시계 도료의 분열기구에 대한 실험적 연구)

  • Kang, S.I.;Lee, S.Y.;An, S.M.;Ryu, S.U.
    • Journal of ILASS-Korea
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    • v.12 no.3
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    • pp.138-145
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    • 2007
  • In the present work, the breakup mechanism of highly viscous epoxy paints discharged from a fan spray nozzle was examined experimentally. The paints tested were non-Newtonian fluids, composed of epoxy resin, solid particles and other additives. The paint spray discharged from the nozzle was visualized and recorded using a digital camera with back illumination. Due to presence of the solid particles, perforation of liquid sheet was observed in most cases, even at low-Reynolds number conditions (Re < 15,000) where the aerodynamic-wave breakup mode is used to be dominant for pure liquids. However, with the increase of the particle concentration, the sheet became longer and the thickness at breakup became thinner to some extent. This is because, with higher concentration of solid particles, the stabilizing effect by the viscosity increase predominates over the destabilizing effect by perforation.

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An Experimental Study for Fluidized Bed Behaviour with Temperature Change. (유동층(流動層)의 온도변화(溫度變化)에 따른 유동특성(流動特性)에 관한 실험적(實驗的) 연구(硏究))

  • Baek, Ko-Kil;Seo, Jeong-Yun
    • Solar Energy
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    • v.6 no.1
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    • pp.3-11
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    • 1986
  • Minimum fludizing velocities and voidages were investigated for closely sized sand and magnesia particles with mean diameters in the range of $297-841\;{\mu}m$ over the temperature between 15 and $1.000^{\circ}C$. Boundaries between changing behaviour at $Re_{mf}=14$ and Ar=17,000 were observed. In beds of fine particles in Geldart's group "B", the minimum fluidizing velocity ($U_{mf}$) decreased as temperature increased, but not as much as expected on account of the gas viscosity increase, furthermore the increase in the minimum fluidizing voidage (${\in}_{mf}$). With larger particles in group "D", $U_{mf}$ increased, first, with temperature increase because of reduced gas density, and depending on the particle size, $U_{mf}$ reduced as flow conditions moved from turbulent to laminar. Among the correlations predicting $U_{mf}$, Ergun equation agreed best with the experimental data providing that the change in ${\in}_{mf}$ according to temperature is allowed for.

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유기 Hectorite Gel의 Rheology에 미치는 극성연가제에 관한 연구

  • 김창규
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.10 no.1
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    • pp.49-74
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    • 1984
  • Rheology of gels prepared with stearyl dimethyl benzyl ammonium hectorite (SDBAH) and various polar additives in n-butyl acetate was investigated by measuring the viscosity and rheogram. Including generally recognized polar additives, additional studies on the rheogram and viscosity were made with ether-type methyl cellosolve and carbitol, with dimethyl sulfoxide (DMSO) having sulfonyl group, and furthermore with above-mentioned polar additives containing small quantity of water, It was observed that molecular size, dipole moments and dielectric constants of polar additives had a great influence on viscosity increase and rheology of SDBAH gel, and the increase of SDBAH interlayer spacing was important factor in gel formation and viscosity change. It was also shown that thixotropy effect was increased with the increase of polar additive concentration, finally changed to rheopexy from thixotropy as the concentration of polar additives was increased more than about 40% of SDBAH weight. In addition thixotropy changed to rheopexy as the increase of shear rate. It was further found that the aqueous solutions of polar additives (water content, 5-25%) had more effects on rheology than additives without water, and particularly 95clo DMSO solution was the most effective. And the optimum concentration of polar additives showing maximum viscosity in the same SDBAH concentration system was examined.

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