Interfacial tension factors affecting

The negatively charged hydrophilic headgroup of the anionic surfactants may comprise sulfate, sulfonate, sulfosuccinate or phosphate groups attached to an extended hydrophobic backbone [82]. The nature of the hydrophilic group will influence the extent of electrostatic stabilization, the behaviour of the surfactant as a fiinction of pH, the degree of hydrolysis, and the variation of latex stability with time, electrolyte and temperature conditions. The nature of the backbone hydrophobe will influence the adsorption behaviour of the surfactant onto the latex particle surface, its cmc value, the interfacial tension (which affects monomer emulsification), and the extent of steric stabilization, among other factors. 

The mechanism of droplet deformation can be briefly summarized as follows. The factors affecting the droplet deformation are the viscosity ratio, shear stress, interfacial tension, and droplet particle size. Although elasticity takes an important role for general thermoplastics droplet deformation behavior, it is not known yet how it affects the deformation of TLCP droplet and its relationship with the processing condition. Some of... 

Water Uptake. There is evidence to suggest that water uptake caused by capillary forces is the crucial factor in the disintegration process of many formulations. In such systems the pore structure of the tablet is of prime importance and any inherent hydrophobicity of the tablet mass will adversely affect it. Therefore, disintegrants in this group must be able to maintain a porous structure in the compressed tablet and show a low interfacial tension towards aqueous fluids. Rapid penetration by water throughout the entire tablet matrix to facilitate its breakup is thus achieved. Concentrations of disintegrant that ensure a continuous matrix of disintegrant are desirable and levels of between 5 and 20% are common. 

Kellerhals, G.E. and Chiou, C.S. "Use of Perspective Plots to Aid in Determining Factors Affecting Interfacial Tensions Between Surfactant Solutions and Crude Oil," Soc. Pet. Eng. J.. June 1982, 350-352. 

Movements in the plane of the interface result from local variations of interfacial tension during the course of mass transfer. These variations may be produced by local variations of any quantity which affects the interfacial tension. Interfaeial motions have been ascribed to variations in interfacial concentration (H6, P6, S33), temperature (A9, P6), and electrical properties (AlO, B19). In ternary systems, variations in concentration are the major factor causing interfacial motion in partially miscible binary systems, interfacial temperature variations due to heat of solution effects are usually the cause. 

Emulsification is a stabilizing effect of proteins a lowering of the interfacial tension between immiscible components that allow the formation of a protective layer around oil droplets. The inherent properties of proteins or their molecular conformation, denaturation, aggregation, pH solubility, and susceptibility to divalent cations affect their performance in model and commercial emulsion systems. Emulsion capacity profiles of proteins closely resemble protein solubility curves and thus the factors that influence solubility properties (protein composition and structure, methods and conditions of extraction, processing, and storage) or treatments used to modify protein character also influence emulsifying properties. 

Literature data is almost entirely for small equipment whose capacity and efficiency cannot be scaled up to commercial sizes, although it is of qualitative value. Extraction processes are sensitive because they operate with small density differences that are sensitive to temperature and the amount of solute transfer. They also are affected by interfacial tensions, the large changes in phase flow rates that commonly occur, and even by the direction of mass transfer. For comparison, none of these factors is of major significance in vapor-liquid contacting. 

Efficient phase separation is critical, since cross-phase contamination has an inherently adverse effect on mass-transfer efficiency. In addition, carryover of solvent in aqueous effluent streams results in loss of solvent from the process, impacting process economics. Phase separation is affected by several physicochemical factors, including the viscosities and densities of the opposing bulk phases and the interfacial tension of the two-phase system. All of these properties contribute to the dimensionless dispersion number, which describes the tendency of two dispersed phases to separate... 

The factors affecting the design of mechanically agitated liquid-liquid reactors are the miscibility of the liquid phases, the interfacial tension, and the densities and viscosities of the liquid phases, as well as the density and viscosity differences between the two liquids. As shown in Fig. 21, a variety of stirrer configurations are available to carry out liquid-liquid reactions. 

Horvath and his co-workers have successfully adapted (36) the sol-vophobic theory as put forward by Sinanoglu et al. (37, 3S) to evaluate AC assoc and, hence, the factors affecting solute retention under a wide range of experimental conditions. This theoretical approach reveals that the capacity factor is a function inter alia of the interfacial surface tension... 

Figure 13. Electrophoretic mobility (Fen Kem 3000) of the emulsion from Figure 12 after cationic polymer addition (A). The cationic polymer has neutralized the oil droplet surface charge and electrostatically destabilized the emulsion. The photomicrograph (B) shows this destabilized emulsion that has begun to flocculate or a lomerate but that is not coalescing. This electrostatic destabilization is not the only factor affecting emulsion stability. Factors such as interfacial tension and film strength can prevent coalescence of the emulsion droplets, even though they can now closely approach each other and ag omer-...

The utility of liquid-liquid extraction as a separation tool depends upon both phase equilibria and transport properties. The most important physical properties that influence transport properties are liquid-hquid interfacial tension, liquid density, and viscosity. These properties influence solute diffusion and the formation and coalescence of drops, and so are critical factors affecting the performance of hquid-liquid contactors and phase separators. 

The flow rate of both phases, viscosity, density, surface tension, and size and shape of the packing determine the value of a . These same factors affect the value of the mass transfer coefficients Ky and Kx. Therefore, it is expedient to include a in the mass transfer equation and define two new quantities KyU and Kxa. These quantities would then be correlated with the solution parameters as functions of various chemical systems. If A is the absorption tower cross-sectional area, and z the packing height, then Az is the tower packing volume. Defining Ai as the total interfacial area ... 

Thermodynamic and Kinetic Effects on Polymorphic Outcome Because of the interplay between thermodynamic factors (free energies, solubilities, concentrations, interfacial tensions), temperature, and molecular recognition in determining nucleation of a new phase, it is essential to consider the effects of thermodynamic and kinetic factors when using solvents to selectively nucleate polymorphs. Threlfall (2000) has thoroughly considered thermodynamic and kinetic factors and the conditions in which the solvent may or cannot affect polymorphic outcomes. The analysis is briefly summarized here. 

The reduction of the tension at an interface by a surfactant in aqueous solution when a second liquid phase is present may be considerably more complex than when that second phase is absent, i.e., when the interface is a surface. If the second liquid phase is a nonpolar one in which the surfactant has almost no solubility, then adsorption of the surfactant at the aqueous solution-nonpolar liquid interface closely resembles that at the aqueous solution-air interface and those factors that determine the efficiency and effectiveness of surface tension reduction affect interfacial tension reduction in a similar manner (Chapter 2, Section IIIC,E). When the nonpolar liquid phase is a saturated hydrocarbon, both the efficiency and effectiveness of interfacial tension reduction by the surfactant at the aqueous solution-hydrocarbon interface are greater than at the aqueous solution-air interface, as measured by pC2o and IIcmc, respectively. The replacement of air as the second phase by a saturated hydrocarbon increases the tendency of the surfactant to adsorb at the interface, while the tendency to form micelles is not affected significantly. This results in an increase in the CMC/C2o ratio. Since the value of rm, the effectiveness of adsorption (Chapter 2, Section IIIC), is not affected significantly by the presence of the saturated hydrocarbon, the increase in the... 

There are usually many candidate solvents for any particular application. Important factors to consider are (1) the affinity of the solute for the solvent (i.e., its distribution coefficient should be large) (2) the affinity of other species in the mixture for the solvent (i.e., their distribution coefficients should be small) (3) solvent safety considerations (e.g., flammability and toxicity) (4) solvent handling properties such as density, viscosity, and vapor pressure (5) solvent solubility in the raffinate phase (high solubilities may translate into high solvent losses unless steps are taken to prevent such losses) and (6) solvent cost. In addition, liquid-liquid interfacial tension affects the interfacial area and the rate of mass transfer between the phases. 

It is also seen that there are great differences between systems, both in the preexponential factor—which primarily affects the overall level of the nucleation rate—and in the exponential factor—which primarily determines the steepness of the curve with respect to temperature. The difference Teq — Thom roughly equals 40 K for ice, 28 K for sucrose, and 26 K for tristearate in paraffin oil. In natural fats, where triglycerides crystallize from a triglyceride oil, the temperature difference is only about 20 K, presumably because the interfacial tension between oil and crystal is far smaller (about 4 rather than lOmN-m-1). 

The presence of liquid crystalline phases, their intermolecular structure and especially their state of dispersion definitely can affect interfacial tensions and interfacial tension transients (10), and may also influence other factors such as viscosity and the retention of surfactant during flow through a porous medium. 

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