Surface tension, measurement techniques

Amin MS, Elborai S, Lee SH, He X, Zahn M (2005) Surface tension measurement techniques of magnetic fluids at an interface between different fluids using perpendicular field instability. J Appl Phys 97 10R308... 

Surface tension measurement techniques are divided into methods for solids and liquids. There are two modes for measuring the surface tension of liquids static and dynamic. Values reported in the literature are often static surface tensions of liquids. Tables 2.1-2.3 present a brief description of the common techniques for surface tension measurement of liquid and solid materials. Some of these methods have been described in further detail. 

The surface tension measurement techniques can be divided into the following three categories (i) Force Methods, which include the truly static methods of the capillary rise and Wilhelmy plate methods, as well as the dynamic detachment methods of the Du Nouy ring and drop weight, (ii) Shape Methods, which include the pendant or sessile drop or bubble, as well as the spinning drop methods, and (iii) Pressure Methods, which are represented by the maximum bubble pressure method. These techniques are summarized in the following sections of this chapter. 

Surface composition and morphology of copolymeric systems and blends are usually studied by contact angle (wettability) and surface tension measurements and more recently by x-ray photoelectron spectroscopy (XPS or ESCA). Other techniques that are also used include surface sensitive FT-IR (e.g., Attenuated Total Reflectance, ATR, and Diffuse Reflectance, DR) and EDAX. Due to the nature of each of these techniques, they provide information on varying surface thicknesses, ranging from 5 to 50 A (contact angle and ESCA) to 20,000-30,000 A (ATR-IR and EDAX). Therefore, they can be used together to complement each other in studying the depth profiles of polymer surfaces. 

Capacitance and surface tension measurements have provided a wealth of data about the adsorption of ions and molecules at electrified liquid-liquid interfaces. In order to reach an understanding on the molecular level, suitable microscopic models have had to be considered. Interpretation of the capacitance measurements has been often complicated by various instrumental artifacts. Nevertheless, the results of both experimental approaches represent the reference basis for the application of other techniques of surface analysis. 

Surface tension measurements. Solutions of the betaines were prepared with quartz-condensed, distilled water, specific conductance, 1.1 X 10" mho cm" at 25°C. All surface tension measurements were made by Wilhelmy vertical plate technique. Solutions to be tested were immersed in a constant-temperature bath at the desired temperature 0.02°C and aged for at least 0.5 h before measurements were made. The pH of all solutions was > 5.0 (usually, in the range 5.5-5.9), where surface properties show no change with pH. 

The synthesis and purification of C12BMG by the reaction of N-methyl-benzylamine with sodium chloroacetate followed by the quaternization of the resulting tertiary ammonioacetate with 1-bromododecane is described elsewhere (12). Purification of aqueous solutions of the surfactant for surface tension measurements and determination of the surface tension of the solutions by the Wilhelmy method using a sandblasted platinum blade were by techniques previously described (13). The concentration of C12BMG in aqueous solution was determined by measuring its absorbance at 263 nm (e = 350.5). 

Initially, this mechanism was proposed on the basis of results obtained for zeta potential and flotation (Fig. 29). The formation of the hydrophobic aggregates at the interface was confirmed after the advent of the fluorescence probing technique. The adsorption isotherm is determined in the presence of pyrene as the fluorescent probe and the emission spectra of pyrene in both supernatant and slurries were analyzed after adsorption. The h/h of pyrene in solutions of SDS containing 0.1 M NaCl and in the slurry are shown in Figs. 30 and 31. In solution, the ratio remains at around 0.6 till the CMC (as determined by surface tension measurement) is attained. Above CMC, the value becomes 1.0 due to the solubilization of pyrene in micelles. In... 

Such a development would be impossible without the generation of new experimental techniques extending the possibilities of studies of supramolecular systems. One such new technique is the vibrational (or infrared-visible) spectroscopy sum frequency generation [8] enabling one to lookatjustthe outer monolayer, thus providing more information than more standard methods like contact angle and surface tension measurements [9]. 

In this section, we present a few examples of instruments available for visual observation and imaging of colloids and surfaces, for measurement of sizes and for surface force measurements. Such a presentation can hardly be comprehensive in fact, that is not our purpose here. Throughout the book, we discuss numerous other techniques such as osmotic pressure measurements, light and other radiation scattering techniques, surface tension measurements,... 

Surface Tension Measurements. These were made with the Wilhclmy balance technique 1 The pipeline crude remained in contact with its own vapor throughout the measurements... 

Micelle formation of the nonionic detergent sorbitan monostearate in o-xylene, particularly the temperature dependence of the CMC, has been observed by Brown et al.I6 The data were obtained from surface tension, dye solubilization, and light scattering measurements. With regard to the CMC values the results derived from these techniques agreed reasonably well. The AH- and AS-values evaluated from the remarkable temperature dependence of the CMC cannot claim to be more than an estimate. Two different values of AH and AS at 25 and 45 °C were determined due to the considerable variation of the heat of micellization with temperature. The discrepancies between the values referring to dye solubilization and surface tension measurements are probably reasonable. 

The interface between plastic and wood fibres strongly influences the mechanical properties of a plastic/wood fibre composite. A means for evaluating the effectiveness of surface treatment on the wood fibres in the PVC/wood fibre composites is presented that investigated the adhesion between PVC and laminated wood veneers. Wood veneers were first treated with gamma-aminopropyltriethoxysilane, dichlorodiethylsilane, phthalic anhydride, and maleated PP for surface modification. The chemical modification made on the wood surfaces was then characterised by different complementary surface analytical techniques X-ray photoelectron spectroscopy and surface tension measurements. 63 refs. 

J. K. Spelt and E. I. Vargha-Butler. "Contact Angle and Liquid Surface Tension Measurements General Procedures and Techniques," in Applied Surface Thermodynamics (A. W. Neumann and J. K. Spelt, eds.). Surfactant Science Series. Vol. 63. Marcel Dekker. New York. 1996. pp.. 379-411. 

J. K. Spelt, M.A.Se. thesis, Surface Tension Measurements of Biological Cells Using the Freezing Front Technique," University of Toronto, 1980. 

Our understanding of miniemulsion stability is limited by the practical difficulties encountered when attempting to measure and characterize a distribution of droplets. In fact, most of the well-known, established techniques used in the literature to characterize distributions of polymer particles in water are quite invasive and generally rely upon sample dilution (as in dynamic and static laser light scattering), and/or shear (as in capillary hydrodynamic fractionation), both of which are very likely to alter or destroy the sensitive equihbrium upon which a miniemulsion is based. Good results have been obtained by indirect techniques that do not need dilution, such as soap titration [125], SANS measurements[126] or turbidity and surface tension measurements [127]. Nevertheless, a substantial amount of experimental evidence has been collected, that has enabled us to estabhsh the effects of different amounts of surfactant and costabihzer, or different costabilizer structures, on stabihty. 

Addison, C.C. (1943) The properties of freshly formed surfaces. Part I. The application of the vibrating-jet technique to surface-tension measurements of mobile liquids. J. Chem. Soc. 535-541. 

A.W. Neumann, R.J. Good, Techniques for Measuring Contact Angles, in Surface and Colloid Science, Vol. 2 (1979), E. Matijevic, Ed., p. 31. (Review contains many technical details relevant for surface tension measurements.)... 

Examples for charged monolayers cam be found from the literature by more or less following the scheme used for non-ionics, i.e. first discuss what can be obtained from surface tension measurements and then consider other techniques, obviouslywith a certain emphasis on the electrostatics. We shall not consider the classes anionic and cationic separately, notwithstanding the sometimes significant difference in behaviour and application. A number of monolayer properties involving charge effects have already been included in sec. 3.8b. There, lyotropic sequences were already discussed. 

Various experimental methods for dynamic surface tension measurements are available. Their operational timescales cover different time intervals. - Methods with a shorter characteristic operational time are the oscillating jet method, the oscillating bubble method, the fast-formed drop technique,the surface wave techniques, and the maximum bubble pressure method. Methods of longer characteristic operational time are the inclined plate method, the drop-weight/volume techniques, the funnel and overflowing cylinder methods, and the axisym-metric drop shape analysis (ADSA) " see References 54, 55, and 85 for a more detailed review. 

Surface tension measurements were made via the advancing contact-angle (yc) technique (15) with a Rame-Hart rheogoniometer. Values for yc are estimated to be accurate to 1.0 dyn/cm. 

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