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Measurement surface tension

The film pressure is defined as the difference between the surface tension of the pure fluid and that of the film-covered surface. While any method of surface tension measurement can be used, most of the methods of capillarity are, for one reason or another, ill-suited for work with film-covered surfaces with the principal exceptions of the Wilhelmy slide method (Section II-6) and the pendant drop experiment (Section II-7). Both approaches work very well with fluid films and are capable of measuring low values of pressure with similar precision of 0.01 dyn/cm. In addition, the film balance, considerably updated since Langmuir s design (see Section III-7) is a popular approach to measurement of V. [Pg.114]

An interesting change of the UV-absorbances with electrolyte concentration was observed for A18 and T18, as shown in Fig. 5. The molar extinction coefficient of A18 decreased by about 7% at 0.09 mM, and that of T18 about 10% at 0.16 mM. These concentrations may correspond to the critical micelle concentration, since the cmc observed from the surface tension measurements were about 0.1 mM for both A18 and T18. [Pg.146]

Table 17 shows the CMCs of sodium alcohol propoxysulfates at 20°C determined from surface tension measurements by the maximum bubble pressure [127] and Table 18 shows the critical micelle concentrations of sodium pro-poxylated octylphenol and propoxylated nonylphenol sulfates. Surface tension... [Pg.254]

When the CMC determination is made by surface tension measurements, the resulting curve appears without minimum as a single surfactant. It is probable that an inversion takes place through the adsorption of the LSDA onto the surface of the Ca soap micelle, so that complete precipitation does not occur [23]. Zhang and Xiao [32] are of the opinion that the dispersion comes from the union of LSDA with the free ionic soap molecules. The particles from the soap-LSDA mixture are far larger than the corresponding soap molecules in soft water and therefore result in turbidity in hard water. [Pg.641]

While the method based on the surface tension measurement has been established since the pioneering work of Gouy, conceptual and experimental problems arise with solid electrodes, whose surfaces cannot... [Pg.31]

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. [Pg.69]

Capacitance and Surface Tension Measurements of Liquid Liquid Interfaces Zdenek Samec... [Pg.12]

The interpretation of phenomenological electron-transfer kinetics in terms of fundamental models based on transition state theory [1,3-6,10] has been hindered by our primitive understanding of the interfacial structure and potential distribution across ITIES. The structure of ITIES was initially studied by electrochemical and thermodynamic analyses, and more recently by computer simulations and interfacial spectroscopy. Classical electrochemical analysis based on differential capacitance and surface tension measurements has been extensively discussed in the literature [11-18]. The picture that emerged from... [Pg.190]

Kakiuchi et al. [75] used the capacitance measurements to study the adsorption of dilauroylphosphatidylcholine at the ideally polarized water-nitrobenzene interface, as an alternative approach to the surface tension measurements for the same system [51]. In the potential range, where the aqueous phase had a negative potential with respect to the nitrobenzene phase, the interfacial capacity was found to decrease with the increasing phospholipid concentration in the organic solvent phase (Fig. 11). The saturated mono-layer in the liquid-expanded state was formed at the phospholipid concentration exceeding 20 /amol dm, with an area of 0.73 nm occupied by a single molecule. The adsorption was described by the Frumkin isotherm. [Pg.437]

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. [Pg.439]

Howell, E. 2001. Dynamic surface tension measurements of liquid solder using oscillating jets of elliptical cross section. Mechanical and Industrial Engineering. University of Illinois at Chicago, Chicago, IL. pp. 75. [Pg.406]

It is known from laboratory tests that surface tension measurement can provide reliable information regarding existing detergent concentration. Work is being carried out in various institutes on such sensors for the commercial sector. However, for use in domestic washing machines, only sensors that are extremely inexpensive, maintenance-free and durable are suitable. How much of a breakthrough can be achieved here in the future remains to be seen. [Pg.31]

K. Tauer, C. Dessy, S. Corkery, K.-D. Bures, On-line surface tension measurements inside stirred reactors , Colloid Polymer Sci. 1999, 277, 805-811. [Pg.114]

Some of the compounds described in this chapter were studied for specific physical properties. Surface tension measurements with solutions of 9-16 in 0.01 M hydrochloric acid demonstrated that these zwitterionic X5Si-silicates are highly efficient surfactants.21 These compounds contain a polar (zwitterionic) hydrophilic moiety and a long lipophilic z-alkyl group. Increase of the n-alkyl chain length (9-15) was found to result in an increase of surface activity. The equilibrium surface tension vs concentration isotherms for 9 and 16 were analyzed quantitatively and the surface thermodynamics of these surfactants interpreted on the molecular level. Furthermore, preliminary studies demonstrated that aqueous solutions of 9-16 lead to a hydrophobizing of glass surfaces.21... [Pg.227]

Encouraged by the results from static surface tension measurements, we next ran force-area curves on 3N, 6N, and ION acids. As Figure 33 indicates, there is pronounced discrimination between the racemic and enantiomeric monolayers, and those differences are sharply dependent on the subphase acidity, as had been impUed by the surface tension behavior. [Pg.246]

Equilibrium spreading pressures, like static surface tension measurements, provide a means to determine surface energies under equilibrium conditions. On lOA H2SO4, racemic crystals (Fig. 10) spread within 5 min to an equilibrium pressure of 8.6 dynes/cm, whereas about 8 hr was required by either (i )-(+)- or (5)-(-)- crystals to spread to a final pressure of 5.5 dynes/cm. [Pg.247]

Fig. 5, curve 1, shows - for dodecyl ether sulfates - the areas occupied by a molecule at c as a function of the number, m,of EO groups. The values were calculated by the Gibbs equation from the surface tension measurements. For 0 - m - 2 there is an area increase with increasing m, however, considerably... [Pg.11]

The molar absorptivities for the two betaines and the three sulfobetaines in aqueous solution are listed in Table I. Before being used for surface tension measurements, aqueous solution of surfactants were further purified by repeated passage (12) through minicolumns (SEP-PAK Cjs Cartridge, Waters Assoc., Milford Mass.) of octadecylsilanized silica gel. The concentration of surfactant in the effluent from these columns was determined by ultraviolet absorbance, using the molar absorptivities listed in Table I. [Pg.51]

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. [Pg.52]

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). [Pg.62]

CMC values were obtained from dye (azobenzene) solubilization and surface tension measurements. Values of 7f used in the above equation were obtained via extrapolation (4-5). For very low values of Mjj, there is concern about... [Pg.119]

The aggregation behavior of C21-DA salt in dilute electrolyte medium appears to resemble that of certain polyhydroxy bile salts (25,16). That C21-DA, with a structure quite different from bile acids, should possess solution properties similar to, e.g., cholic acid is not entirely surprising in light of recent conductivity and surface tension measurements on purified (i.e., essentially monocarboxylate free) disodium salt aqueous solutions, and of film balance studies on acidic substrates (IX) The data in Figure 3 suggest that C21-DA salt micelles Incorporate detergents - up to an approximate weight fraction of 0.5 -much like cholate Incorporates lecithin or soluble... [Pg.120]

Surface Tension Measurement. Surface tension was determined with a Rosano Tensiometer (Arenberg-Sage Inc., Jamaica Plain, Mass.) utilizing a sand-blasted platinum blade. [Pg.131]

CED values can be determined from surface tension measurements, (2) the effects of particular molecular components of surfactant molecules on surface tension and CED can be addressed, and (3) the emulsion type and stability can be evaluated based on either molecular structure surface tension and/or CED. [Pg.260]

Surface Tension Measurements. The surface tension of surfactant... [Pg.294]


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