Contact angles and interfacial tension

Maze and Burnet [61,62] developed a more satisfactory scheme for the determination of contact angle and interfacial tension from the shape of sessile drops both above and below 90. They utilized a numerical nonlinear regression procedure in which a calculated drop shape is made to fit a number of arbitrary selected and measured points on the drop profile. In other words, the measured drop shape (one-half or the meridian section) is described by a set of coordinate... 

Dispersion behaviour in systems with liquid/liquid or liquid/gas interfaces (i.e. droplet or bubbles) has traditionally been described in terms of rheological properties, wetting properties, including contact angle and interfacial tensions, or phase behaviour and stability measurements. Direct force measurements provide a means to fundamentally probe the interactions between deformable interfaces that significantly impact the dispersion (or emulsion) behaviour. 

Figure A. Contact angles and interfacial tensions of oil-water-emulsifier systems with middle phases as a function of the emulsifier partition between oil and water.

To quantify the effects of mixed waste con sition on wettability and interfacial tension equilibrium, aqueous phase receding contact angle and interfacial tension were measured. Inter cial tension was measured ida a spinning drop tensiometer Model 500 (University of Texas, Austin, TX) and contact angles were obtained using axisymmetric drop shape analysis (17) on quartz slides. Contact angles are reported through the aqueous phase. 

By incorporating the definition of and Wq (see Contact angles and interfacial tension), Eqn. 1 can be rearranged to give the Good-Girifalco equation for interfacial tension Yi2 in terms of the Surface energy values yi and yi of the two phases... 

See Contact angles and interfacial tension for the definitions and a note on nomenclature of the surface energy terms. It is important to realize that Eqn. 2 depends only on the definitions, and so is universally valid. 

Considerations, such as these, have lead Good and others to use the term Lifshitz-van der Waals forces when referring in the context of Contact angles and interfacial tension and Surface energy components to weak interactions between molecules. 

Debye and Keesom forces together with London Dispersion forces are known coiiec-tively as van der Waals forces. See Lifshitz-van der Waals forces for a further discussion. They play a significant role in the Adsorption theory of adhesion and in surface phenomena such as Contact angles and interfacial tension. 

Other related articles are as follows Contact angles and interfacial tension. Infrared spectroscopy. Pre-treatment of fluorocarbon polymers. Primers for adhesive bondii. Roughness of surfaces. Surface analysis. 

Related articles are Adsorption theory of adhesion, Contact angles and interfacial tension. Pre-treatments of polymers. Surface energy. Wetting and spreading. 

These ideas are farther developed in other articles, in particnlar. Surface characterization by contact angles - polymers. Wetting and spreading, Wetting and work of adhesion, Contact angles and interfacial tension. Pre-treatments of polymers and Pretreatment of metals prior to bonding. 

This equation should be compared with Eqn. 2 in Contact angles and interfacial tension, where the subscript notation is explained. 

Equation 4 applies to an interface across which only dispersion forces act if other forces act as well, there must be another negative term on the right-hand side, giving the further lowering of interfacial energy (see Contact angles and interfacial tension, Eqn. 2, and Surface characterization by contact angles - polymers, Eqn. 4). Over the years, it... 

Contact angles and interfacial tension D E PACKHAM Young s equation work of adhesion, interfacial tension and surface energy... 

In this section, let us eonsider the macroscopic wetting behavior of an axisymmetric meniscus from a thermodynamic viewpoint and discuss the possibility of the measurement of the contact angle and interfacial tension [61]. As in the analysis stated above, the theoretical consideration is based on the assumption described by Eq. (9). 

In previous studies , Good-Girifalco plots were constructed using both the contact angle and interfacial tension data obtained with PEG/DEX biphasic systems on a variety of cell types. The resultant critical interfacial tension for spreading applied only to a particular PEG/DEX mixture, and thus lacked generality and strict comparability. 

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