Surface tension

About: Surface tension is a research topic. Over the lifetime, 25410 publications have been published within this topic receiving 695471 citations.

The dependence of contact angles on drop size and line tension

Abstract: We report contact angle measurements of five n-alkanes, dodecane through hexadecane, on Teflon (FEP) as a function of drop size. In all cases the contact angles decreased by approximately 5° when the drop size was increased from approximately 1 to 4 mm contact radius. A complete solution to the problem of mechanical equilibrium of a sessile drop on a solid surface indicates that the dependence of the contact angle on drop size may be explained by including the effect of line tension in the Young equation. The observed drop size dependence of the contact angle yields a line tension of (2.5 ± 0.5) × 10−6 J/m. Over the range of n-alkanes studied it was not possible to discern any dependence of the line tension on liquid surface tension.

The Motion of Bubbles and Drops Through Liquids

Abstract: Publisher Summary Chemical engineers, metallurgists, geologists, brewers and cooks all try to understand processes in which bubbles or drops move through liquids. Because interfacial phenomena affect the motion in a number of different ways, there are many cases to consider. The simplest case is a bubble rising in a Newtonian liquid, far enough from boundaries to be treated as if isolated. It is assumed that the viscosity and density of the internal gas are negligible, and that the surface rheology reduces to the single parameter of a constant uniform surface tension. Another case is concerned with drops, whose interior viscosity and density are taken into account, but which satisfy the other conditions of Newtonian liquid. The most restrictive condition is constancy of the surface tension, for it requires exceptionally pure fluids. Experiments seldom agree with the predictions of above mentioned cases for small bubbles or drops unless great care is taken to remove impurities. These adsorb at the surface and lower the surface tension. The flow of the fluid then carries the impurities around the surface, setting up inequalities of concentration and hence of surface tension, which oppose the motion. The chapter contains an account of the motion of drops and bubbles in the ideal solutions of surfactants.

Direct determination of surface tension in the lung.

Abstract: We have used the spreading behavior of small drops of several fluorocarbon fluids and silicone oil on air-liquid interfaces to measure the surface tension of lungs in situ. The test fluids were calibrated in a surface balance at 37 degrees on monolayers of dipalmitoylphosphatidylcholine. At particular surface tensions characteristic of each fluid used, an increase in the tension of 1 mN/m or less caused the droplets to spread reversibly from a sphere to a lens shape. Using micropipettes we placed such droplets on the alveolar surfaces of excised rat lungs held at functional residual capacity and 37 degrees and found that the surface tension remained below 9 mN/m for at least 30 min. The surface tension-volume relationship was linear for tensions ranging from 9 to 20 mN/m.

Surface free-energy components of liquids and low energy solids and contact angles

Abstract: Employing the values of organic liquid surface tension and interfacial surface tension of water-organic liquid, values of dispersion and nondispersion components of these liquids were calculated and compared with those obtained in another way. For these organic liquids and water, the values of the contact angle on paraffin wax, polytetrafluoroethylene, polyethylene, polyethylene terephthalate, and polymethyl methacrylate were measured. The values of dispersion and nondispersion components of surface free energy of these polymers and paraffin wax were calculated using the measured values of the contact angle for diiodomethane and water and the calculated values of the components of their surface tension. These calculated data were in agreement with the literature data. Taking our values of free energy components of liquids and solids, the values of the contact angle for these solids were calculated and compared with those measured, obtaining good agreement. On the basis of the measurements and calculations it was found that dispersion and nondispersion components of surface free energy of liquids and solids “work well” in the systems studied.

Interfacial Phenomena: Equilibrium and Dynamic Effects

Abstract: FUNDAMENTALS OF INTERFACIAL TENSION Introduction to Interfacial Phenomena Interfacial Tension: Qualitative Considerations Interfacial Tension: Thermodynamic Approach Interfacial Tension: Mechanical Approach Density and Concentration Profiles Equilibrium Shapes of Fluid Interfaces Methods of Measuring Interfacial Tension Surface Tension of Binary Mixtures Surfactants Solid-Fluid Interfaces FUNDAMENTALS OF WETTING, CONTACT ANGLE, AND ADSORPTION Young's Equation Work of Adhesion and Work of Cohesion Phenomenological Theories of Equilibrium Contact Angles Acid-Base Interaction Contact Angle Hysteresis Adsorption Density Profiles in Liquid Films on Solids Characterizing Solid Surfaces COLLOIDAL DISPERSIONS Attractive Forces Electrical Interaction Colloids of All Shapes and Sizes Combined Attractive and Electrical Interaction: DLVO Theory Effect of Polymer Molecules on the Stability of Colloidal Dispersions Kinetics of Coagulation SURFACTANTS Micelle Formation Variation of CMC for Pure Surfactants and Surfactant Mixtures Other Phases Involving Surfactants Formation of Complexes Between Surfactants and Polymers Surface Films of Insoluble Substrates Solubilization and Microemulsions Phase Behavior and Interfacial Tension for Oil-Water-Surfactant Systems Effect of Composition Changes Thermodynamics of Microemulsions Applications of Surfactants: Emulsions Applications of Surfactants: Detergency Chemical Reactions in Micellar Solutions and Microemulsions INTERFACES IN MOTION: STABILITY AND WAVE MOTION Linear Analysis of Interfacial Stability Damping of Capillary Wave Motion by Insoluble Surfactants Instability of Fluid Cylinders or Jets Oscillating Jet Stability and Wave Motion of Thin Liquid Films: Foams Energy and Force Methods for Thermodynamic Stability of Interfaces Interfacial Stability for Fluids in Motion: Kelvin-Helmholtz Instability Waves on a Falling Liquid Film TRANSPORT EFFECTS ON INTERFACIAL PHENOMENA Interfacial Tension Variation Interfacial Species Mass Balance and Energy Balance Interfacial Instability for a Liquid Heated from Below or Cooled from Above Interfacial Instability During Mass Transfer Other Phenomena Influenced by Marangoni Flow Nonequilibrium Interfacial Tensions Effect of Surfactant Transport on Wave Motion Stability of Moving Interfaces with Phase Transformation Stability of Moving Interfaces with Chemical Reaction Intermediate Phase Formation Transport-Related Spontaneous Emulsification Interfacial Mass Transfer Resistance Other Interfacial Phenomena Involving Dispersed Phase Formation DYNAMIC INTERFACES Surfaces Basic Equations of Fluid Mechanics Flow Past a Droplet Asymptotic Analysis Dip Coating Spherical Drop Revisited Surface Rheology Drainage of Thin Liquid Films Dynamic Contact Lines Slip Thin and Ultrathin Films SIZE, SHAPE, STRUCTURE, DIFFUSIVITY, AND MASS TRANSFER Probing with Light More Light Diffraction Diffusion Dynamic Light Scattering NMR Self-Diffusion Coefficient *Each chapter provides an Introduction, General Topic and Text References, and Problems. Worked examples also appear throughout the chapters.