Showing papers on "Surface tension published in 1988"
TL;DR: In this paper, it was shown that the relation between contact angles and the three controlling parameters ybw, yg, and 7s of a polar solid, S, cannot be established by means of one single equation.
Abstract: It is demonstrated that, while the Lifshitz-van der Waals (rLW) and the polar, Lewis acid-base (rAB) surface tension components are additive, the Lewis acid-base electron-acceptor (7') and electron-donor (y-) surface tension parameters (which on account of the intrinsic asymmetry of their interactions are connected in a more complex manner) are not additive. Contact angle data cannot, in general, be correlated with a single surface tension property. The relation between contact angles and the three controlling parameters ybw, yg, and 7s of a polar solid, S, cannot be established by means of one single equation. These three unknowns can, however, be determined by means of contact angle measurements with three different liquids L (of which two must be polar and H-bonding), which are completely characterized as to their respective rkw, yL+, and y i parameters by using a modified Young-Good-GirifalcoFowkes equation 3 times. In view of these considerations. recent claims to have proven the applicability of a single "equation of state" are shown to be spurious.
1,256 citations
TL;DR: In this article, the authors survey recent theoretical work which elucidates how such systems arrive at their observed patterns, focusing on dendritic solidification, simple local models thereof, and the Saffman-Taylor finger in 2D fluid flow.
Abstract: A variety of non-equilibrium growth processes are characterized by phase boundaries consisting of moving fingers, often with interesting secondary structures such as sidebranches. Familiar examples are dendrites, as seen in snowflake growth, and fluid fingers often formed in immiscible displacement. Such processes are characterized by a morphological instability which renders planar or circular shapes unstable, and by the competing stabilizing effect of surface tension. We survey recent theoretical work which elucidates how such systems arrive at their observed patterns. Emphasis is placed upon dendritic solidification, simple local models thereof, and the Saffman-Taylor finger in two-dimensional fluid flow, and relate these systems to their more complicated variants. We review the arguments that a general procedure for the analysis of such problems is to first find finger solutions of the governing equations without surface tension, then to incorporate surface tension in a non-perturbative manne...
626 citations
Book•
31 Dec 1988
TL;DR: This book discusses the properties of Colloids, the structure of which has changed over time, and the role of surface chemistry in the development of these properties.
Abstract: Chapter 1: What are Colloids? Chapter 2: Why are Colloidal Dispersions Stable? Basic Principles Chapter 3: Why are Colloidal Dispersions Stable? Interparticle Forces Chapter 4: How are Colloidal Dispersions Prepared? Chapter 5: What is the Role of Surface Chemistry? Surface Tension and Adsorption Chapter 6: Some Important Properties of Colloids I Kinetic Properties Chapter 7: Some Important Properties of Colloids II Scattering Radiation Chapter 8: Some Important Properties of Colloids III Rheology Chapter 9: How are Colloidal Dispersions Destroyed? I Aggregation Processes Chapter 10: How are Colloidal Dispersions Destroyed? II Coalescence and Particle Growth Chapter 11: Association Colloids and Self-Assembly Systems Chapter 12: Thin Films, Foams and Emulsions Chapter 13: Gels Chapter 14: The Industrial Importance of Colloids Chapter 15: The Future of Colloid Science
600 citations
01 Jun 1988-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the Gibbs and Langmuir adsorption isotherms were used to calculate the entropy and enthalpy of surface active components such as oxygen, sulfur, selenium, and tellurium.
Abstract: Since the fluid flow, heat transfer, and the resulting weld properties are significantly affected by interfacial tension driven flow, the variation of interfacial tension in dilute binary solutions is studied as a function of both composition and temperature. Entropy and enthalpy of adsorption of surface active components such as oxygen, sulfur, selenium, and tellurium in Fe-O, Fe-S, Fe-Se, Cu-O, Cu-S, Cu-Se, Cu-Te, Ag-O, and Sn-Te systems were calculated from the analysis of the published data on interfacial tension of these systems. For these calculations, a formalism based on the combination of Gibbs and Langmuir adsorption isotherms was used. Interfacial tensions in Cr-O, Co-S, and Ni-S systems, where the data are scarce, were predicted by using certain approximations. The computed values were found to be in reasonable agreement with the data available in the literature. Temperature coefficients of interfacial tensions were calculated for several binary systems. It was demonstrated that in dilute solutions, the temperature coefficient of interfacial tension is strongly influenced by the heat of adsorption which, in turn, is influenced by the difference in electronegativity between the solute and solvent ions.
470 citations
TL;DR: In this paper, a treatment to deal with dynamic surface tension data of surfactant solutions is suggested, which is divided into four stages: induction region, fast fall region, meso-equilibrium region, and equilibrium region.
320 citations
TL;DR: In this paper, surface tension and surface excess energy are calculated, from which surface excess entropy is evaluated, and surface potential χ can be evaluated to be about +0.16 V at T=300 K, which confirms recent experimental results.
Abstract: Molecular dynamics simulations have been carried out for liquid–vapor interface of water and also of Lennard‐Jones system. Surface tension and surface excess energy are calculated, from which surface excess entropy is evaluated. These thermodynamic quantities suggest the existence of some liquid‐structural change near the surface of water, which is not seen in Lennard‐Jones system. For water, orientational structuring near the surface is studied and two types of orientation are found. In the vapor side, a water molecule has a tendency of projecting one hydrogen atom toward the vapor, and in the liquid side, a molecule prefers to lie down on the surface with both hydrogen atoms slightly directed to the liquid. From these results, surface potential χ can be evaluated to be about +0.16 V at T=300 K, which confirms recent experimental results. The ellipticity coefficient is also discussed and the assumption often used in analysis of experimental results of ellipsometry is found to be inadequate for water due ...
273 citations
TL;DR: In this article, the surface structure and properties of miscible blends of polystyrene (PS) with polyvinyl methyl ether (PVME) have been studied as a function of the blend composition and constituent molecular weights.
Abstract: : The surface structure and properties of miscible blends of polystyrene (PS) with poly(vinyl methyl ether) (PVME) have been studied as a function of the blend composition and constituent molecular weights. The lower surface tension of the PVME compared to that of PS results in preferential adsorption of PVME at the surface. The surface PVME enrichment is characterized by measurements of the surface tension as a function of the temperature, accomplished with an automated pendant drop apparatus, and by x-ray photoelectron spectroscopy (XPS). Angle-dependent XPS has been used to determine the surface concentration profiles of the blend constituents.
247 citations
TL;DR: In this paper, the surface tension of a liquid-vapor interface has been determined accurately in a molecular dynamics simulation, and it is shown that the usually truncated tail of the potential strongly increases the surface tensor if taken into account.
Abstract: The surface tension of a Lennard‐Jones liquid–vapor interface has been determined accurately in a molecular dynamics simulation. Our values tend to be smaller than those from previous simulations. It is shown that the usually truncated tail of the potential strongly increases the surface tension if taken into account.
234 citations
Journal Article•
201 citations
TL;DR: In this paper, a thermodynamic treatment is developed wherein the surface concentration of ionic surfactants is distinguished from their surface excess concentration by the contribution from the electrical double layer.
187 citations
TL;DR: In this article, the effect of temperature and number average molecular weight on interfacial tension between immiscible homopolymers is measured using an automated pendant drop apparatus, which utilizes Video Digital Image Processing techniques.
Abstract: : Interfacial tensions between immiscible homopolymers are measured using an automated pendant drop apparatus, which utilizes Video Digital Image Processing techniques. A recently developed robust shape analysis algorithm is used to analyze the experimental drop profiles. The data show the effect of temperature and number average molecular weight (Mn) on the interfacial tension for the immiscible blends polystyrene-poly(methyl methacrylate), polybutadiene-poly(dimethyl siloxane) and polystyrene-hydrogenated 1,2 polybutadiene. Interfacial tension decreases linearly with temperature and increases with molecular weight. The data for all three systems can be approximated by an empirical relationship. The interfacial tension data for the latter blend system are compared with thermodynamic theories of polymeric interfaces. A square gradient theory approach, in conjunction with the Flory-Huggins expressions for the free energy of mixing, predicts a magnitude and temperature dependence of interfacial tension which are in reasonable agreement with experimental data, and does predict a molecular weight dependence which roughly follows the empirical relationship.
01 Jan 1988
TL;DR: In this article, the pull-off force between molecularly smooth mica surfaces has been measured as a function of the relative vapor pressure of cyclohexane, n-hexane and water.
Abstract: The pull-off force between molecularly smooth mica surfaces has been measured as a function of the relative vapor pressure of cyclohexane, n-hexane, and water. For the experiments with water both normal mica (with surface potassium ions) and ion-exchanged mica (covered with hydrogen ions) have been used. The results of an earlier study (L. R. Fisher and J. N. Israelachvili, Colloids Surf. 3, 303 (1981)) have been shown to lead to erroneous conclusions due to the use of a rolling and shearing spring. Here a nonrolling and virtually shear-free double cantilever spring has been used. At high relative vapor pressures (p/ps ≳ 0.7) the pull-off force for all vapors is dominated by the Laplace pressure in a capillary-condensed annulus. There is a small but noticeable contribution from a solid-solid interaction across the annulus, but surface deformations do not appear to affect the measured pull-off force. As the relative vapor pressure decreases from ∼0.7 to 0, the pull-off force varies smoothly and approaches its value in the “dry” state. There is no difference in behavior between water and the nonpolar liquids other than can be explained in terms of the solid-solid contribution to the adhesion. It is concluded that such measurements do not give any immediate information on the validity of the bulk surface tension for very high (r
TL;DR: A review of the literature data pertaining to the surface tension of pure iron and iron binary alloys is presented in this article, where approximate surface activities of the alloying elements have been deduced.
Abstract: A review has been conducted of the literature data pertaining to the surface tensions of pure iron and iron binary alloys. Approximate values for the respective surface activities of the alloying elements have been deduced. Of particular note are the high surface activities exhibited by Group VI elements in iron, together with the positive temperature coefficients of surface tension found with these alloys. Literature data for the suggested surface structures of the melts, based upon adsorption measurements, are included in this review.
TL;DR: In this article, numerical algorithms for surface tension and viscosity are presented in the context of a Lagrangian treatment of incompressible hydrodynamics with a dynamically restructuring grid.
TL;DR: In this paper, the authors investigated the nonlinear evolution of initially small disturbances at an interface separating two fluids of different density and velocity, including surface tension effects, with the use of the vortex-sheet discretization approach.
Abstract: The nonlinear evolution of initially small disturbances at an interface separating two fluids of different density and velocity, including surface tension effects, is investigated with the use of the vortex‐sheet discretization approach. The location of the interface is tracked in time by following the motion of each vortex under the combined influence of all other vortices. The influence of surface tension and density discontinuity is incorporated in an equation governing the evolution of the circulation of each vortex. Increasing the surface tension or the density ratio is shown to reduce the growth of the disturbance. For density ratios larger than 0.2 a critical wavenumber exists that divides the unstable part of the spectrum into a region where a vorticity singularity can develop (with interface rollup) and a region where two finite vortical centers are formed (with partial or no rollup). For lower density ratios this bifurcation phenomenon is not observed.
TL;DR: In this article, the effect of ethanol on the critical micelle concentration (CMC) of several surfactant aqueous solutions has been studied by surface tension methods, and the results show that with increasing alcohol concentration the CMC values first reach a minimum at an intermediate ethanol mole fraction x2* ≈ 0.055 and then increase with increasing x2.
Patent•
16 Feb 1988TL;DR: In this paper, a method for preparing stable even coatings of a silicone lubricant on a low surface energy polymeric surface of an article includes plasma treatment of the surface in an atmosphere of a siloxane monomer.
Abstract: A method for preparing stable even coatings of a silicone lubricant on a low surface energy polymeric surface of an article includes plasma treatment of the surface in an atmosphere of a siloxane monomer. A layer of polysiloxane is deposited on the low energy surface to give a polysiloxane surface. A film of a polysiloxane lubricant having a surface tension substantially the same as or less than the surface energy of the polysiloxane surface is applied to the polysiloxane layer.
TL;DR: In this article, steady state relative permeabilities as functions of interfacial tension were measured with the highly volatile methane-propane system, and the most important conclusions to be derived from this work are that the curvatures of the relative permeability curves diminish as the interfacial tensor is reduced, the irreducible gas and liquid saturations approach zero as the interfacial tension approaches zero, and relative gas-oil permeabilities for gas-condensate reservoirs are altered from the normal relative
Abstract: Relative permeabilities are believed to be influenced by interfacial tension through capillary forces in porous rocks. An experimental procedure was developed and used with the highly volatile methane-propane system. The objective was to measure steady state relative permeabilities as functions of interfacial tension. Interfacial tension level of the methane propane mixture, which is considered to be representative of a gas-condensate system, was varied by changing the steady state pressure of the experiment. Individual relative permeability curves obtained as a function of gas saturation approach the 45/sup 0/ diagonals for both gas and oil as the interfacial tension level is lowered. At the highest interfacial tension for which experiments were performed (0.82 dynes/cm), the relative permeability curves approached those obtained for a nitrogen-kerosene flood for which the interfacial tension is approximately 30 dynes/cm. The methane-propane mixtures were prepared in the laboratory. Compositions were determined with a chromatograph. The most important conclusions to be derived from this work are that the curvatures of the relative permeability curves diminish as the interfacial tension is reduced, the irreducible gas and liquid saturations approach zero as the interfacial tension approaches zero, and relative gas-oil permeabilities for gas-condensate reservoirs are altered from the normal relative permeabilitiesmore » only at pressures, temperatures and compositions close to the critical point.« less
TL;DR: In this article, the conditions for obtaining the electrocapillary curves of the dilauroylphosphatidylcholine (DLPC) monolayer formed at the polarized nitrobenzene-water interface have been studied using the pendant drop method.
Abstract: The conditions for obtaining the electrocapillary curves of the dilauroylphosphatidylcholine (DLPC) monolayer formed at the polarized nitrobenzene–water interface have been studied using the pendant drop method. To facilitate the measurement, the system for the interfacial tension measurement, including the computer software for the data handling, has been developed based on digital image processing of the video image of a pendant drop. The 95% confidence interval of the measured interfacial tension value was ±0.06 mN m−1. The time required to measure an electrocapillary curve with 30 points was 30 min, while the time necessary to convert the image data to the interfacial tension was 1 min. The potential drop across the monolayer has been demonstrated to influence the stability of the monolayer strongly. The DLPC markedly lowered the interfacial tension by forming a stable monolayer when the interface was polarized so that the aqueous phase has a negative potential with respect to the nitrobenzene phase. ...
TL;DR: In this paper, the authors examined the wicking flow in random fiber networks for various pure liquids and surfactant solutions and found that all liquids used obey the rate law of the simple Lucas-Washburn theory, indicating depletion of surfactants from the wetting front by adsorption onto the fiber surfaces during penetration.
TL;DR: In this paper, the surface tension of water, hexadecane, silicone oil, and aqueous solutions of glycerin levitated in air has been measured, and the results have been compared with those obtained with standard ring tensiometry.
TL;DR: In this paper, a three-parameter generalized equation for surface tension from the triple point to the critical point was proposed, which not only fits the data well but also is good for interpolation between the normal boiling point and critical point.
Abstract: A three-parameter generalized equation is proposed for surface tension from the triple point to the critical point. This equation not only fits the data well but also is good for interpolation between the normal boiling point and the critical point. This equation is also good for extrapolation to the triple point. This equation has been tested using the surface tension of water from the triple point to the critical point. The constants of this equation obtained using orthobaric surface tensions are given for a number of compounds. The isobaric surface tensions determined at a pressure of 1 atm do not differ significantly from the orthobaric surface tensions. Such data also have been used in obtaining equations from the triple to the critical point.
TL;DR: In this article, the effect of surface tension on steady-state rotating fluids in a low-gravity environment is studied and the profile of the interface of two fluids is derived from Laplace's equation relating pressure drop across an interface to the radii of curvature that has been applied to a low gravity rotating bubble that contacts the container boundary.
Abstract: The effect of surface tension on steady-state rotating fluids in a low-gravity environment is studied. AH values of the physical parameters used in the present calculations, except in the low-gravity environments, are based on the measurements carried out by Leslie in the low-gravity environment of a free-falling aircraft. The profile of the interface of two fluids is derived from Laplace's equation relating pressure drop across an interface to the radii of curvature that has been applied to a low-gravity rotating bubble that contacts the container boundary. The interface shape depends on the ratio of gravity to surface-tension forces, the ratio of centrifugal to surface tension forces, the contact radius of the interface to the boundary, and the contact angle. The shape of the bubble is symmetric about its equator in a zero-gravity environment. This symmetry disappears and gradually shifts to parabolic profiles as the gravity environment becomes nonzero. The location of the maximum radius of the bubble moves upward from the center of the depth toward the top boundary of the cylinder as gravity increases. The contact radius of interface to the boundary r0 at the top side of cylinder increases, and r0 at the bottom side of the cylinder decreases as the gravity environment increases from zero to 1 g.
Book•
01 Jan 1988
TL;DR: In this paper, the role of adsorption layers of polymers in stabilizing dispersal polymers is discussed, as well as the influence of low-molecular-mass surfactants on the properties of dispersed polymers.
Abstract: 1. General Colloid Chemistry of Polymers. General. Dispersion in colloidal polymer systems. 2. Microheterogeneous Structure of One- and Multi-Component Polymer Substances. Modern concepts of the structure of amorphous polymers. Structural heterogeneity of polymers. 3. Structure Formation in Disperse Polymer Systems. Thermodynamics of the formation of particles of a new phase. Theory of spinodal decomposition. Phase separation in polymer systems. Dissipative processes as a cause of microheterogeneity in polymer systems. 4. Surface Tension in Disperse Systems. Surface tension of solutions. Surface tension of polymer melts. Surface tension of solid polymers. 5. Surface-Active Properties of Polymers and the Influence of Low-Molecular-Mass Surfactants on the Properties of Disperse-Polymer Systems. Polymers as surfactants. Influence of surfactants on the properties of oligomers and polymers. Influence of surfactants on the strength and destruction of polymers. 6. Adsorption of Polymers on Solid Surfaces. Adsorption from dilute solutions. Isotherms of polymer adsorption from dilute solutions. Aggregation mechanism of adsorption. Some features of polymer adsorption kinetics on highly dispersed adsorbents. The role of adsorption layers of polymers in stabilizing disperse systems. Adsorption from polymers blends. 7. Polymer Adhesion. Thermodynamic description. Adhesion strength. Adhesion theory. Mechanism of adhesion joint formation. Internal stresses in adhesion joints. Colloid-chemical approaches to the increase of adhesion strength. 8. Structure and Properties of Surface and Interfacial Polymer Layers. Surface layers of polymer phases. Surface layers of polymers on the surface of solids. Interfacial layers in heterogeneous mixtures of polymers. Features of the interfacial region structure in polymer mixtures. Microheterogeneity of surface layers. Monomolecular layers of polymers. 9. Filled Polymers as Disperse Systems. General. Structure formation in polymers in the presence of dispersed fillers. Mechanical properties of filled polymers. Rheological properties of filled polymers. Surface modifications of fillers. Mechanisms of reinforcing action of fillers in polymers. Polymers filled with colloidal metals. 10. Colloidal Mixtures of Polymers. Theoretical concepts of mixing and compatability of polymers. Empirical determination of polymer compatability. Features of diagrams of the state of binary mixtures. Rheological properties of binary mixtures. 11. Colloid-Chemical Features of Polymer-Polymer Systems. Separation of polymer-polymer systems. Thermodynamics of the formation of stable dispersion systems. Dispersity of polymer-polymer compositions. Colloidal and chemical structure of polymer-polymer systems. 12. Gelation of Solutions Polymer Gels. Classification of polymer gels. Gel-formation conditions. Mechanism of gel-formation processes and structure of polymer gels. Phase state of polymer gels. Polymer gels as disperse colloidalsystems. 13.
TL;DR: In this paper, the profile of a thin liquid film completely wetting a rough solid surface was studied and it was shown that the long-wavelength undulations of the liquid interface follow those of the solid surface, while short wavelength undulations are strongly damped.
Abstract: We study the profile of a thin liquid film completely wetting a rough solid surface. The long-wavelength undulations of the liquid interface follow those of the solid surface, while short-wavelength undulations are strongly damped. There is Lorentzian damping of wavelengths smaller than the healing length ξ determined by a balance between surface tension and disjoining pressure. Undulations with wavelength smaller than the mean film thickness e are exponentially damped. We study in detail the case where the binary interactions between molecules may be described by an inverse power law potential such as the Van der Waals potential. These results are relevant for recent ellipsometry and grazing incidence x-ray scattering experiments.
TL;DR: In this article, a differential interference microscope was used to observe the separation of crude oil droplets from a solid silica surface in the presence of a micellar solution, and the mechanism of oil droplet separation appeared to be a combination of both a rolling-up mechanism and a diffusional mechanism.
01 Jan 1988
TL;DR: In this paper, the surface-tension gradient due to temperature or concentration gradients in the free melt surface is considered as a driving force for convection in crystal growth from the melt, and it is shown that surface tension-driven flow is especially important in small melt volumes, near the free surface of larger volumes, or under conditions of weightlessness.
Abstract: Convection is an important parameter in crystal growth from the melt. A driving force for convection besides buoyancy, crystal rotation and crucible rotation, is the surface-tension gradient due to temperature or concentration gradients in the free melt surface. This article points out that in the various melt-growth techniques with free melt surface, e.g. the floating-zone technique, the Czochralski technique and the open-boat zoning, surface-tension-driven flow is likely to occur and to influence the growth. Surface-tension-driven flow is especially important in small melt volumes, near the free surface of larger volumes, or under conditions of weightlessness (e.g. in Spacelab). Under the large temperature gradients encountered in crystal growth, surface-tension-driven flow can become time dependent. Numerical studies, experiments on surface-tension-driven flow, and observations in real growth systems are reviewed.
TL;DR: In this paper, the effect of surface tension, buoyant force, gravitational force, and particle motion during collision was taken into account. But the authors did not consider the impact of the surface tension on contact times.
Abstract: Contact time during bubble/particle collision is calculated by taking into consideration the effect of surface tension, buoyant force, gravitational force, and particle motion during collision. From this analysis for the estimation of contact times and from induction lime measurements, the flotabilities of different coals have been predicted. A good agreement between the predicted and experimentally measured Hallimond-tube flotation response was found
TL;DR: In this article, a three-dimensional model of the thermocapillary flow within the molten region during laser surface heating is developed, which physically corresponds to the process of a stationary laser beam irradiating on the surface of a moving workpiece.
Abstract: A three‐dimensional model of the thermocapillary flow within the molten region during laser surface heating is developed. This physically corresponds to the process of a stationary laser beam irradiating on the surface of a moving workpiece. The recirculating flow due to the surface tension gradient is much faster than the scanning motion. This allows a perturbation solution. The basic solution corresponds to the stationary axisymmetric case, and the perturbation is based on a small scanning velocity. The advantage of seeking a perturbation solution is that the three‐dimensional flow is modeled by two sets of two‐dimensional equations which are presumably much more tractable than the original three‐dimensional equations. Numerical solutions are obtained. The solid‐liquid interface is determined by an iterative scheme. In the presence of the recirculating flow, the heat transfer becomes convection dominated. The absorbed laser energy is convected sideways so that a wider and shallower molten region is obta...