• Title, Summary, Keyword: Surface Tension

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Surface Tension and Antithrombogenicity of Silk Fibroin Films Graft-Copolymerized with Methyl Methacrylate and Styrene by Cold Methane Plasma Initiation (저온 메탈플라스마 전처리 견피브로인 막에의 메틸메타크릴레이트 및 스티렌의 그라프트 공중합, 막의 표면장력 및 항혈전성)

  • Ha, Wan-Sik;No, Il-Jun;Kim, Jun-Ho
    • Textile Science and Engineering
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    • v.26 no.4
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    • pp.33-41
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    • 1989
  • Silk fibroin was dissolved in calcium chloride/ethanol/water mixture(1/2/8 in mole ratio)at 7$0^{\circ}C$ for 4hrs. The dissolved silk fibroin was regenerated by casting the dialyzed solution into the film. The films were treated with 50% aqueous methanol solution for 15 min. Then the films were graft-copolymerized with methylmethacrylate and styrene by methane plasma initiation and their antithrombogenicities were investigated by the methods of blood clotting and platelet adhesion tests. The results from the two "in vitro" tests were analyzed in connection with surface tension of the film. It was found that the antithrombogenicity of films was improved by the surface grafting and varid with the fraction of polar component of surface tension to the total surface tension of film.n of film.

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A New Model and Equation Derived From Surface Tension and Cohesive Energy Density of Coagulation Bath Solvents for Effective Precipitation Polymerization of Acrylonitrile

  • Zhou, You;Xue, Liwei;Yi, Kai;Zhang, Li;Ryu, Seung Kon;Jin, Ri Guang
    • Carbon letters
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    • v.13 no.3
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    • pp.182-186
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    • 2012
  • A new model and resultant equation for the coagulation of acrylonitrile monomers in precipitation polymerization are suggested in consideration of the surface tension (${\gamma}$) and cohesive energy density ($E_{CED}$). The equation was proven to be quite favorable by considering figure fittings from known surface tensions and cohesive energy densities of certain organic solvents. The relationship between scale value of surface tension (${\gamma}$/M) and cohesive energy density of monomers can be obtained by changing the coagulation bath component for effective precipitation polymerization of acrylonitrile in wet spinning.

Surfactant Aided Air-sparging for Groundwater Remediation (계면촬성제 첨가에 따른 지하수 폭기법의 폭기효율 변화 연구)

  • 소효은;최경민;이승재;김헌기
    • Economic and Environmental Geology
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    • v.35 no.5
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    • pp.421-428
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    • 2002
  • Lab-scale experiments were conducted to evaluate the effect of surface tension reduction on the extension of the influence zone and the VOC removal efficiency of ground water sparging. A glass column packed with coarse sand was used for VOC removal test at two different surface tensions. A glass column without porous media was also used fer control purpose prior to sand-packed column test. A quasi-two-dimensional glass box model, packed with a sand, was used fer sparging zone tests at different water surface tensions. Surface tension of the aquoues solution used in this study was controlled using sodium dodecyl sulfate (SDS). For the glass, sand column experiments, total amount of air filled in the media increased as surface tension decreased. Toluene (used as VOC in this study) removal rate increased slightly with decreased surface tension f3r both free water column and sand-packed column. Air sparging zone extended up to 500% as the surface tension decreased. Combining the results from two different experiments, VOC removal efficiency is expected to increase significantly with surface tension reduction.

A Study on Vortex Pair Interaction with Fluid Free Surface (자유표면에 작용하는 와동 현상에 대한 연구)

  • Sohn K.;Ryu H. K.;Kim K. H.;Kim S. W.
    • 한국가시화정보학회:학술대회논문집
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    • pp.67-72
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    • 2002
  • Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. another purpose of this study is to investigate the effect of surface active material which can change the surface tension and we must consider when we refer to turbulent flow on surface tension. therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before, and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

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A Study on Vortex Pair Interaction with Fluid Free Surface

  • Kim, K.H.;Kim, S.W.
    • Journal of ILASS-Korea
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    • v.10 no.4
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    • pp.26-31
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    • 2005
  • Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. Another purpose of this study is to investigate the effect of surface active material which call change the surface tension and we must consider when we refer to turbulent flow on surface tension. Therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before. and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

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A Study on the Viscosity and Surface Tension for Foaming Materials and the Effects of Addition Elements (발포재료(Al)의 점성 및 표면장력과 첨가요소의 영향에 관한 연구)

  • Park, Soo-Han;Kim, Sang-Youl;Ahn, Duck-Kyu;Ha, Dong-In;Cho, Soon-Hyung;Bae, Suk-Cheon;Hur, Bo-Young
    • Korean Journal of Materials Research
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    • v.12 no.9
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    • pp.729-734
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    • 2002
  • Porous Al metal was produced by batch type casting process. In this foaming process, the viscosity and surface tension of molten Al as two most important factors have been investigated in the temperature range of 680-95$0^{\circ}C$ by the ring method and rotational method respectively. The experimental results showed that both the surface tension and viscosity of the melt decreased linearly with increasing temperature. Addition of Ca decreased surface tension, but increased viscosity significantly.

Analysis of Surface Crack under Tension and Bending Stress in Plate (인장과 굽힘응력을 받는 판재의 표면균열해석)

  • 오환섭;박철희;허민구
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.4
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    • pp.121-128
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    • 1998
  • In this study, when tension and bending stress act on plate simultaneously, stress intensity factor is analyzed at crack tip with using BEM(Boundary Element Method). In this analysis, stress intensity factors(S.I.F) are defined for variable ligament, aspect and stress ratio($\sigma$T/$\sigma$B). Consequently, predicted that crack grow to depth direction at low aspect and ligament ratio in tension stress and to surface direction in bending stress. Tension and bending stress act on plate same time, effect of tension stress in the first stage and effect of bending stress in the after stage was to observed. The outbreak of secondary crack in backside is under the control of stress amplitude and predict that the point of outbreak is mear backside.

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Purification and Characterization of Biosurfactant from Tsukamurella sp. 26A

  • Choi, Kyung-Suk;Kim, Soon-Han;Lee, Tae-Ho
    • Journal of Microbiology and Biotechnology
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    • v.9 no.1
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    • pp.32-38
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    • 1999
  • A biosurfactant produced by Tsukamurella sp. 26A was purified by procedures including acid precipitation, ethylacetate extraction, and adsorption chromatography. The purified biosurfactant reduced the surface tension of water from 72 mN/m to 30 mN/m at a concentration of 250 mg/l, whereas the minimum interfacial tension against n-hexadecane was lowered to 1.5 mN/m at a concentration of 40 mg/i. The compound stabilized oil-in-water emulsions with a variety of commercial oils and had strong emulsification and stabilization activities when compared to those of commercial emulsifiers and stabilizers. Surface tension was stable over a broad range of pH (2-12) and temperature ($100^{\circ}C$, 3h). The biosurfactant was identified as glycolipid having a hydrophilic moiety of trehalose.

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A Molecular Dynamics Study of Thermophysical Properties and Stability of Nanoscale Liquid Thread (분자동역학 해석을 이용한 액체 극미세사의 열역학적 물성과 안정성 연구)

  • Kim, Byeong-Geun;Choi, Young-Ki;Kwon, Oh-Myoung;Park, Seung-Ho;Lee, Joon-Sik
    • Proceedings of the KSME Conference
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    • pp.1366-1371
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    • 2003
  • Molecular dynamics (MD) simulations are conducted to investigate the thermophysical characteristics and the stability of liquid threads for various conditions. A cylindrical thread in the simulation domain is made of Lennard-Jones molecules. The surface tension of liquid threads can be determined from local densities, local normal and transverse components of the pressure force. In order to understand the effects of thread radii on surface tensions, the Tolman equation is modified on the basis of the cylindrical coordinates for prediction of surface tensions. Surface tensions calculated from the MD simulation agree with the prediction from the modified Tolman equation. In addition, surface tensions decrease linearly with increasing system temperature. For a binary system, the surface tension decreased linearly compared to that for a pure system with increasing binary ratio of solute molecules which have relatively large value of the affinity coefficient. For a fixed binary ratio, the surface tension increased slightly with the affinity coefficient and the maximum value appear around where the affinity coefficient is 1.5 and decreased rapidly for upper value of 1.5. In addition, the critical wavelengths of perturbations are proven to be directly proportional to the equimolar dividing radii of the liquid threads.

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Effect of Physical Properties of Polymer Solution on the Thickness of Ultrathin Membrane Prepared by Water Casting Method (고분자용액의 물성이 수면전개 박막의 두께에 미치는 영향)

  • Nam, Suk-Tae;Han, Myeong-Jin;Choi, Ho-Sang;Park, Young Tae
    • Applied Chemistry for Engineering
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    • v.9 no.2
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    • pp.200-206
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    • 1998
  • The effect of surface tension and viscosity of polymer solution on the thickness of water casting membranes was studied. Spreading of polymer solutions on water surface was governed by the surface tension and viscosity of the polymer solution. The thickness of water casting membrane was affected by these two factors. The properties, mentioned above, were proportional to the polymer concentration. The order of magnitude in surface tension was PVC>PS>CA and that of viscosity was CA>PS>PVC. The difference of surface tension between water and polymer solution acts as driving force for spreading of polymer solution, but the viscosity as resistance. The thickness of polymeric membrane prepared by water casting was PS>CA>PVC. The order of membrane thickness was not as same as that of surface tension. This phenomena were due to the viscosity which acts as more effective spreading resistance than the surface tension.

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