Showing papers on "Surface tension published in 1974"
TL;DR: Pure bending of a membrane bilayer is developed including different properties for each membrane half, and chemically induced moments are considered as a possible mechanism for crenation of red blood cells.
643 citations
01 Nov 1974
TL;DR: In this paper, an equation of state is developed which allows the surface tension of a low-energy solid to be determined from a single contact angle formed by a liquid which is chemically inert with respect to the solid and whose liquid surface tension is known.
Abstract: An equation of state is developed which allows the surface tension of a low-energy solid to be determined from a single contact angle formed by a liquid which is chemically inert with respect to the solid and whose liquid surface tension is known. The equation of state is obtained using two independent methods. In the first one, similar arguments to those in previous papers are used; however, the qualitative argument, based on the general appearance of plots, is replaced by computer curve fitting and statistical analysis. The second method, which has not been employed heretofore, treats the solid surface tension as an adjustable parameter. Molecular arguments in conjunction with the interaction parameter Φ are used to eliminate poor choices of the solid surface tension. The results are in excellent agreement with the first method. The range of validity of the equation of state and practical points in its application are discussed.
636 citations
TL;DR: From the experimental results, the free energies of transfer of the amino acid residues from the solution to the surface have been calculated to yield a hydrophobicity scale of the residues, in fairly good agreement with that of Nozaki and Tanford.
449 citations
TL;DR: In this article, the electrical conductance, density, viscosity, and surface tension of fluoride mixtures have been systematically collected and evaluated for 44 binary mixtures over a range of compositions and temperatures.
Abstract: Data on the electrical conductance, density, viscosity, and surface tension of fluoride mixtures have been systematically collected and evaluated. Results are given for 44 binary mixtures over a range of compositions and temperatures. Values of the above properties for the single salts have been updated in accord with previously advanced recommendations.
343 citations
TL;DR: In this paper, the thermodynamics of a solid-liquid-vapor system both under chemical equilibrium and nonequilibrium conditions, based on the model of Gibbs, are discussed, and the degree of wetting or nonwetting of a flat and nondeformable solid by the liquid is defined by Young's equation in terms of the static interfacial tensions.
Abstract: The thermodynamics of a solid-liquid-vapor system both under chemical equilibrium and nonequilibrium conditions, based on the model of Gibbs, is discussed. Under chemical equilibrium conditions, the degree of wetting or nonwetting of a flat and nondeformable solid by the liquid is defined by Young's equation in terms of the static interfacial tensions. Under chemical nonequilibrium conditions, mass transfer across an interface results in a transient decrease in the corresponding specific interfacial free energy and the interfacial tension by an amount equal to the free energy of the effective chemical reaction per area at that interface. When the reaction is between the solid and the liquid, this transient lowering of the interfacial tension can cause the liquid drop to spread on the solid substrate if the interfacial energy reduction is large enough and also if the diffusion rates of the reacting components in the solid phase are slow enough relative to the flow rate of the liquid to cause the liquid at the periphery of the drop to be in dynamic contact with unreacted solid.
313 citations
TL;DR: In this paper, the rates of nucleation of liquid aerosols from the gaseous maxtures H2SO4+H2O and HNO3+H 2O at 25°C for various relative humidities (10% to 100%) and various activities of acid vapor were calculated using the Flood-Neumann-Doring-Reiss-Doyle theory of binary homogeneous necleation.
Abstract: The rates of nucleation of liquid aerosols from the gaseous maxtures H2SO4+H2O and HNO3+H2O at 25°C for various relative humidities (10% to 100%) and various activities of acid vapor are calculated using the Flood‐Neumann‐Doring‐Reiss‐Doyle theory of binary homogeneous necleation The activities of acid vapor needed for nucleation are 25 to 300 times smaller for H2SO4+H2O than for HNO3+H2O This is due to the much larger free energy of mixing in the liquid phase for H2SO4+H2O Conversion from activities to actual pressures leads to condentrations of nitric acid which are much too high to be found under normal atmospheric conditions On the other hand, the concentrations of sulfuric acid vapor needed to nucleate droplets in the H2SO4+H2O system are in the range 4(10−5) to 13(10−2) ppm, a concentration which can result from photo‐oxidation of SO2 in the atmosphere Calculations are made of the growth curves for H2SO4+H2O droplets (radius versus composition) at various relative humidities from the critical size radius up to a 1000 A radius, corresponding to nuclei large enough to serve as condensation centers for heterogeneous nucleation A generalized version of the Kelvin equation which includes the composition dependence of the surface tension for a binary mixture is derived and applied in calculating these growth curves Sign errors in the second derivatives of the free energy in Doyle's paper are corrected The limitations of the binary homogeneous nucleation theory at extremely low concentrations of one of the components are discussed and it is shown that this theory becomes inapplicable if the actual vapor pressure of one component is below 10−6 torr
217 citations
TL;DR: In this paper, the effect of pressure on the surface tension of water was investigated in a number of gas-water systems at 25/sup 0/ using a capillary-rise method.
Abstract: In recent years, there has been a resurgence in interest concerning bulk and surface properties of water. One area of research that has received comparatively little attention concerns the effect of pressure on the surface tension of water. This paper reports results obtained in measuring interfacial tension as a function of pressure for a number of gas-water systems at 25/sup 0/ using a capillary-rise method. The systems involving water with carbon dioxide and nitrous oxide were of particular interest, since it is known that on the one hand these gases are more soluble than expected in bulk water while on the other hand water is abnormally soluble in compressed CO2 and N2O, leading to the question of whether a corresponding anomaly is to be found with respect to adsorption at the interface of water with these 2 gases. (36 refs.)
205 citations
TL;DR: In this article, a Monte Carlo analysis of the surface structure and surface tension of a liquid with molecules interacting according to the Lennard Jones 12-6 potential is described. But the analysis is limited to the case of liquid argon.
Abstract: A Monte Carlo computation of the surface structure and surface tension of a liquid with molecules interacting according to the Lennard‐Jones 12–6 potential is described. The computation demonstrates the presence of a well‐developed layer structure at the surface extending to a depth of about eight molecular layers. The calculated surface tension agrees well with that predicted by Toxvaerd's extension of the Barker‐Henderson perturbation theory to nonuniform fluids. The latter theory also predicts well the averaged behavior of the surface density profile (though not the development of the layered structure). This theory is used with accurate pair and triplet potentials to calculate values of the surface tension of liquid argon that agree quantitatively with experiment over a wide range of temperatures.
181 citations
01 Nov 1974
TL;DR: In this article, the surface thermodynamics of a two-component three-phase solid-liquid-vapor system is considered, and it is shown that an equation-of-state type of relation exists between the solid vapers, the solid liquid, and the liquid vapor interfacial tensions.
Abstract: The surface thermodynamics of a two—component three—phase solid—liquid—vapor system is considered. Under the assumption that the solid is ideal, i.e., smooth, homogeneous, rigid, and has no appreciable vapor pressure, it is shown that an equation-of-state type of relation exists between the solid—vapor, the solid—liquid, and the liquid—vapor interfacial tensions. The existence of this relation in conjunction with Young's equation makes it, in principle, possible to determine the solid-vapor and the solid—liquid interfacial tensions from contact angles. A test is described which, on the basis of contact angle data for a solid in contact with several liquids, allows one to decide whether or not adsorption of the vapor of the liquids on the solid is appreciable.
141 citations
Patent•
IBM1
TL;DR: In this paper, a source of energy is selectively applied to a liquid stream to reduce the surface tension of the liquid and is applied before the stream would randomly break up into droplets.
Abstract: A source of energy is selectively applied to a liquid stream to reduce the surface tension of the liquid and is applied before the stream would randomly break up into droplets. Both the quantity of energy applied and the time period that the energy is applied are controlled to control the time to droplet breakoff and the time between droplets by selectively reducing the surface tension of segments of the stream. The source of energy can be high intensity light, which is converted by the stream to heat energy, or a source of heat (resistive or inductive) with the resistive heat being applied to the stream by conduction and the inductive heat being converted by the stream to heat energy.
131 citations
01 Nov 1974
TL;DR: In this paper, Ellipsometrically determined adsorption isotherms are reported for water on two types of pyrolytic carbon, on polyethylene, and on stearic acid-coated copper, for relative pressures up to close to the saturation pressure, P0, and for various temperatures.
Abstract: Ellipsometrically determined adsorption isotherms are reported for water on two types of pyrolytic carbon, on polyethylene, and on stearic acid-coated copper, for relative pressures up to close to the saturation pressure, P0, and for various temperatures. Contact angle data for bulk water on the same solids are included; advancing angles of 60°–90° were found. The adsorbed film thickness reaches 40–80 A in the first two systems, but only a few angstroms in the second two; correspondingly, the surface pressures of P0, π0, are large in the first two cases and small in the second two. Large contact angle thus does not necessarily imply low π0. The data are fitted to a previously published potential-distortion model, which allows adsorption and contact angle behavior to be related.
TL;DR: In this paper, a simple theoretical analysis correctly predicts that at an advancing contact line, i.e., one where liquid replaces gas in contact with the solid, the contact angle exceeds its equilibrium value and flow along the fluid interface is toward the contact line.
TL;DR: In vivo experiments were performed on human subjects to gain quantitative information on the motion of the tear film, and it is postulated that this motion is driven by surface tension gradients, caused by non-uniformities in the concentration of the surface active material found at the tearFilm surface.
TL;DR: In this paper, the effects of fluid viscosity and surface tension on the incipient conditions for vortex formation and on vortex size and shape were investigated in two different sizes of cylindrical tanks with adjustable vanes at the perimetry.
Abstract: Different fluids were used to investigate the effects of fluid viscosity and surface tension on the incipient conditions for vortex formation and on vortex size and shape. Experiments were conducted in two different sizes of cylindrical tanks with adjustable vanes at the perimetry to allow varying degrees of initial circulation to be generated at the entrance to the test section. The results of the experiments demonstrated that: (1) free surface vortex flow is affected by initial circulation and viscosity, but, for the ranges tested, is not affected by surface tension; (2) the coefficient of the discharge is a function of the Reynolds and circulation numbers; and (3) regions in which an air core will or will not form can be defined by the depth of flow, orifice size, and circulation and Reynolds numbers.
TL;DR: In this article, an external wall potential is introduced to stabilize the phase separation and the coexistence curve, surface tension, and surface energy are found to be in good agreement with experimental results.
Abstract: Classical ensembles interacting by Lennard‐Jones (LJ) forces and exhibiting liquid vapor phase separations are investigated for reduced temperatures t = T/Tc from 0.515 to 0.955 by Monte Carlo methods. An external wall potential is introduced to stabilize the phase separation. The coexistence curve, surface tension, and surface energy are found to be in good agreement with experimental results. The film exhibits a layered structure at the lower temperatures. It is proposed that the method can be exploited to study inhomogeneous systems in general and phase coexistence in particular.
TL;DR: In this paper, the authors introduced the concept of a quantitative measure for the efficiency with which surfactants depress surface or interfacial tension is introduced, where the quantity, log (1/C)π=20, where C is the bulk concentration or surfactant required to reduce the surface pressure by 20 dynes/cm (surface pressure, π=20), is a suitable measure of the efficiency.
Abstract: The concept of a quantitative measure for the efficiency with which surfactants depress surface or interfacial tension is introduced. It is shown that the quantity, log (1/C)π=20, where C is the bulk concentration or surfactant required to reduce the surface or interfacial tension by 20 dynes/cm (surface pressure, π=20), is a suitable measure of the efficiency. This quantity is a linear function of the free energy of transfer of the surfactant molecule from the interior of the bulk phase to the interface. The effect upon the efficiency of various structural groupings in both the hydrophobic and hydrophilic portions of the molecule is calculated and the results discussed. From surface and interfacial tension data, it is shown that the free energy decrease involved in the transfer of a −CH2-group at π=20 to the aqueous solution-air interface is 450–500 cal mole−1 at 25 C; for the aqueous solution-heptane interface, the free energy decrease/−CH2-group transferred is greater than 427 cal mole−1 at 50 C.
TL;DR: In this article, the authors used the calculus of variations to determine theoretically the stable equilibria, by calculating the energy change when the liquid in equilibrium experiences axially symmetrical perturbations under physically realistic constraints.
Abstract: In a drop of liquid which hangs below a horizontal support or a t the end of a tube, the forces due to surface tension, pressure and gravity are in equilibrium. Amongst the many possible equilibrium shapes of the drop, only those which are stable occur naturally. The calculus of variations has been used to determine theoretically the stable equilibria, by calculating the energy change when the liquid in equilibrium experiences axially symmetrical perturbations under physically realistic constraints. If the energy change can be made negative, the drop is unstable. With this criterion, stable equilibria have been identified through which the naturally growing drops evolve until they reach a maximum volume, when they become unstable. These results are illustrated by calculations relating to typical experimental conditions.
TL;DR: In this paper, surface concentrations and film pressures of slick-forming organic constituents were measured in situ and on surface water samples from the Pacific Ocean, west of San Diego, and it was estimated that a fourfold compression of the surface layer by horizontal convergent forces was required to create visible slicks at this location.
TL;DR: In this article, the surface tension and its temperature derivative, dγ / dT, were measured by means of Wilhelmy slide techniques for dilute (≤ 1.5 m) aqueous solutions of NaCl, KCl, NaI, and KI.
TL;DR: In this paper, the authors investigated the mechanical equilibrium of solid axisymmetric particles floating in a horizontal fluid/liquid interface in a gravitational field, and the critical sizes of spheroids retained by capillary forces at the interface were calculated as functions of the particle and fluid densities, the interfacial tension, and contact angle on the solid surface.
TL;DR: Compared with other fundamental physical properties of liquid metals, such as surface tension and viscosity, density is more amenable to accurate measurement as mentioned in this paper, making it more suitable for accurate measurement.
Abstract: Compared with other fundamental physical properties of liquid metals, such as surface tension and viscosity, density is more amenable to accurate measurement. Accurate data are highly desirable bec...
TL;DR: In this paper, the authors investigated the role of surface tension and two surface viscosities during the entrapment of residual oil by water and during the subsequent displacement by surfactant solutions.
Abstract: Qualitiative theories are developed to explain the roles of surface tension and the two surface viscosities during the entrapment of residual oil by water and during the subsequent displacement of residual oil by surfactant solutions. The results are in agreement with available experimental data concerning the effects to be observed as the oil-water surface tension is reduced. Limited data suggest an order of magnitude criterion for the critical surface tension above which no residual oil can be recovered. The two surface viscosities do not affect the entrapment of residual oil, but they are predicted to play a major role in the displacement of residual oil by surfactant solutions.
TL;DR: In this article, no correlation of useful predicting power exists between the tendency of a nematic liquid to align transverse to a solid surface and the difference between the surface free energies of the liquid and the substrate.
Abstract: Contrary to recent claims, no correlation of useful predicting power exists between the tendency of a nematic liquid to align transverse to a solid surface and the difference between the surface free energies of the nematic liquid and of the substrate. Observations that lead to this conclusion are reported for systems in which (i) the composition but not the surface tension of the nematic liquid, (ii) the adsorbed layer and hence the surface free energy of the substrate, and (iii) the temperature is varied.
TL;DR: In this article, the authors investigated the thermodynamics of a liquid-metal surface using a pseudo-atom model for the ions and electrons and derived the surface energy and tension following the classical Kirkwood-Buff procedure.
Abstract: The thermodynamics of a liquid-metal surface are investigated using a pseudo-atom model for the ions and electrons. By treating the energy of the electrons as an effective potential for the pseudo-ions, the statistical mechanics of the latter can be evaluated. The surface energy and tension are then derived following the classical Kirkwood-Buff procedure. In the metallic case, the surface energy and tension include indirect effects due to the variation of electron density at the surface as well as the usual direct contribution which arises from the change in the pairwise distribution of atoms caused by the presence of the surface. Some numerical results are presented and compared with experiment. These indicate that, for simple liquid metals, the observed increase in surface tension as a function of increasing bulk electron density is mainly due to an indirect term, that is, the change in self-energy of a pseudo-atom as a function of electron density.
01 Feb 1974
TL;DR: In this paper, surface tension components of chlorobenzene and carbon disulfide have been evaluated by the same method and their spreading pressures on ice were computed, showing that both liquids form autophobic adsorption layers which change the nature of ice surface.
Abstract: Dispersion and polar components of surface free energy of ice have been calculated using the principle of additivity and geometrical mean of similar forces interacting across the interface of contiguous phases. Comparison of those components shows a qualitative difference between ice and water surfaces; ice being predominantly of nonpolar character. Surface tension components of chlorobenzene and carbon disulfide have been evaluated by the same method and their spreading pressures on ice were computed. The results show that both liquids form autophobic adsorption layers which change the nature of ice surface.
TL;DR: The shape of deformed dispersed drops of two-phase systems can be fixed by converting them into a gel state provided the lifetime of these anisodiametrical dispersed particles is not lesser than the transition time as discussed by the authors.
Abstract: 1.
The deformation of dispersed particles of twophase liquid systems investigated by the small-angle light scattering method corroborates the fact that the viscosity ratio between the dispersed and continuous phases is important. Under experimental conditions the deformation is observed atη′/η < 4–6 and it is maximum asη →η. The drop axial ratio increases with shear rate and drop volume, and decreases with increasing interfacial tension.
2.
In principle, the shape of drops deformed in the flow can be fixed by converting the continuous medium into gel state. The resulting anisotropic gel filled with anisodiametrical liquid drops oriented along the direction of shear can be called as capillary-structure gel which are anisotropic by their optical and mechanical properties.
3.
The structure of two-phase liquid systems in the flow is shown to strongly depend on the lifetime of anisodiametrical dispersed drops exhibiting high degree of asymmetry. The dynamic equilibrium, breakdown of liquid cylinder ⇄ coalescence of drops, is also of great importance. When the dispersed phase passes from liquid to gel state, the dynamic equilibrium shifts towards the breakdown of liquid cylinder due to suppressed coalescence of dispersed particles in the gel state.
4.
The shape of deformed dispersed drops of two-phase systems can be fixed by converting them into a gel state provided the lifetime of these anisodiametrical particles is not lesser than the transition time.
TL;DR: In this paper, it was shown that the effect of the presence of surfactant will be more important in the final than in the initial stages of droplet formation, which is relevant to emulsification.
Abstract: The formation of droplets from cylindrical oil films supported by oleophilic filaments has been studied experimentally. In the absence of surfactant, the initial rate of growth of a disturbance on the cylindrical fluid surface was shown to depend on the interfacial tension, the film thickness, cylinder radius and liquid viscosity (as expected by theory). It was shown by theory and experiment that the effect of surfactant is to increase the resistance of the surface against dilational and compressional deformation in such a way that the initial rate of growth of droplets can be decreased by a factor of 4 as compared with the rate for a clean surface.It is argued that the effect of the presence of surfactant will be more important in the final than in the initial stages of droplet formation. This is most obvious for droplet formation from free cylinders, a process relevant to emulsification.
TL;DR: In this article, a silicone-based surfactant was used to increase the efficiency of iron-based spray solutions applied to chlorotic citrus trees for stomatal penetration of leaves.
Abstract: Wetting and stomatal penetration of plant leaves by spray solutions can be obtained when the surface tension of the spray solution is sufficiently low. Low surface tension fluorocarbon and silicone-based surfactants were active at lower concentrations and were found to be less harmful to plant cell membranes than a comparable carbohydrate-based surfactant. A silicone-based surfactant greatly increased the efficiency of iron solutions sprayed onto chlorotic citrus trees.
TL;DR: In this article, the spectrum of light scattered by thermally excited surface waves on water has been investigated and the value of the surface tension and, after careful analysis of instrumental broadening, was determined.
Abstract: The spectrum of light scattered by thermally excited surface waves on water has been investigated and the value of the surface tension and, after careful analysis of instrumental broadening, the value of the viscosity determined. The results are in good agreement with those obtained by more conventional techniques. In contrast to a recent report by McQueen and Lundstrom (ref. (1)) who also performed a light scattering experiment, an anomalously high viscosity was not found. These authors invoked the concept of a highly structured surface region, in order to interpret their data. This region probably does not exist.