Emulsions appearance

Emulsions Appearance (as phase separahon), color, odor, pH, and viscosity... 

Does an emulsion appear when the two phases are vigorously stirred ... 

The emulsifying properties of these polymeric surfactants demonstrate that the chemical structure influences the kinetic behaviour of interfacial tension reduction. An increase of sulfopropyl moieties reduces the interfacial tension slower while an increase in 2-hydroxy-3-phenoxy propyl moieties reduces the interfacial tension faster. The ionic strength of the emulsion appears to increase the rate of tension reduction. The average droplet size of oil-in-water emulsions in presence of previously dissolved 2-hydroxy-3-phenoxy propyl sulfopropyl dextran is around 180 nm immediately after preparation and increases with time. The presence of ionic moieties appeared to facilitate emulsification at low polymer concentrations due to electrostatic repulsions between the oil droplets [229]. 

Microemulsions, like micelles, are considered to be lyophilic, stable, colloidal dispersions. In some systems the addition of a fourth component, a co-surfactant, to an oil/water/surfactant system can cause the interfacial tension to drop to near-zero values, easily on the order of 10-3 - 10-4 mN/m, allowing spontaneous or nearly spontaneous emulsification to very small drop sizes, typically about 10-100 nm, or smaller [223]. The droplets can be so small that they scatter little light, so the emulsions appear to be transparent. Unlike coarse emulsions, microemulsions are thought to be thermodynamically stable they do not break on standing or centrifuging. The thermodynamic stability is frequently attributed to a combination of ultra-low interfacial tensions, interfacial turbulence, and possibly transient negative interfacial tensions, but this remains an area of continued research [224,225],... 

All the emulsions appeared to have similar particle sizes, estimated to be in the range of 0.1-0.5/. The monomers were all polymerization grade and polymerized without purification since no significant difference in induction period or rate was observed with distilled monomer. 

Emulsions Appearance (particularly with regard to phase separation and color), odor, PH, viscosity, and the effects of heating and cooling. 

Chemical nature Non-ionic emulsion Appearance White free-flowing emulsion pH 9.0... 

Chemical nature non-ionic silicone emulsion Appearance white, free-flowing liquid pH 7.5... 

Chemical nature modified silicone emulsion Appearance ivory-colored, pourable liquid Density 8.2 lbs. per gallon... 

Chemical nature Reactive resinous emulsion Appearance Free-flowing, off-white emulsion Solubility Dispersible in water at any concentration Density 8.6 pounds per gallon... 

Chemical nature Combination wax-zirconium salt emulsion Appearance White free flowing liquid pH 4.0-4.5... 

Type Polyethylene emulsion Appearance Milky white pH 7.5 - 8.0 Total Solids 40+-0.5%... 

Type Modified cationic polyolefin emulsion Appearance Tan emulsion pH 3.5... 

Type Modified nonionic acrylic emulsion Appearance White liquid emulsion pH 4.5... 

All of the emulsions appear to be Newtonian in the range of shear rates studied (Fig. 5). No significant change in the viscosity of the fresh emulsions was observed at NaOH concentrations above 6.0 x 10 moles NaOH/gram oil, but the viscosity did decrease as NaOH concentration decreased, particularly below 4 x 10 as shown in Table I and Fig. 5. 

Many successful formulations are based on emulsion techniques. In these formulations, oil and water are mixed in such a way that small, uniformly shaped oil droplets are dispersed in the water phase (oil in water) or water droplets are dispersed in a continuous oil phase (water in oil). An emulsion appears as a cloudy suspension. When an oil-in-water emulsion has oil droplets so small as to produce a clear solution, then formulation is called a microemulsion. The oil phase of the emulsion can provide lipophilic proteins with some protection from enzymatic digestion while the product is in the intestinal tract. Water-in-oil microemulsion formulations have been developed for oral insulin delivery.50... 

As shown in the ASP examples later in this chapter, emulsions increase injection pressure and decrease water injection rate and liquid production rate. However, the advantages of emulsions appear to be greater than the disadvantages (Cheng et al., 2001). 

Values corresponding to surfactants or charged polymeric emulsifiers (only those actually synthesized) that lead preferentially to the formation of OAV and W/O emulsions appear respectively in white and black rectangles. Grey rectangles display HLB values of the most balanced emulsifiers. 

To the naked eye, emulsions appear as uniform, opaque liquids or pastes of vdiite or slightly yellowish color. The microscope reveals that emulsions are by no means uniform substances. They are non-uniform and consist of a multitude of small droplets, usually of spherical shape, and varying diameters, floating in the surrounding liquid. Emulsions with particles... 

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