Emulsion solid

Gas Liquid Solid — Foam Aerosol Emulsiom Aerosol Suspension Solid foam Solid emulsion Solid disersion... 

NOTE In simple filming amine formulations ODA is the most widely employed ingredient. Formulations are typically available as 100% concentrated flakes, 2 to 5% strength aqueous solutions, or 5 to 10% strength emulsions. Solid ODA should be stored without exposure to air because it gradually reacts with carbon dioxide to form ODA carbonate, which is white and crumbly in composition. 

Fig. 44. Schematic representation of Dd/JV plots for microgels formed in emulsion (solid lines) and in solution (dashed line). Solvent = toluene. Temperature = 25°C. The dotted line represents the plot of linear polystyrene. The 1,4-DVB contents are given in the figure. E = Einstein equation.

K049 Waste oil/emulsion/solids from petroleum... 

Phenomena at Liquid Interfaces. The area of contact between two phases is called the interface three phases can have only a line of contact, and only a point of mutual contact is possible between four or more phases. Combinations of phases encountered in surfactant systems are L—G, L—L—G, L—S—G, L—S—S—G, L—L, L—L—L, L—S—S, L—L—S—S—G, L—S, L—L—S, and L—L—S—G, where G = gas, L = liquid, and S = solid. An example of an L—L—S—G system is an aqueous surfactant solution containing an emulsified oil, suspended solid, and entrained air (see Emulsions Foams). This embodies several conditions common to practical surfactant systems. First, because the surface area of a phase increases as particle size decreases, the emulsion, suspension, and entrained gas each have large areas of contact with the surfactant solution. Next, because interfaces can only exist between two phases, analysis of phenomena in the L—L—S—G system breaks down into a series of analyses, ie, surfactant solution to the emulsion, solid, and gas. It is also apparent that the surfactant must be stabilizing the system by preventing contact between the emulsified oil and dispersed solid. Finally, the dispersed phases are in equilibrium with each other through their common equilibrium with the surfactant solution. 

Polytvinyl acetate) and its copolymers with ethylene are available as spray-chied emulsion solids with average particle sizes of 2-20 pm the product can be reconstituted to ail emulsion by addition of water or it can be added directly to formulations, e.g., concrete. 

Acrylic emulsion - The emulsion consisted of suspended crosslinked (gel) particles that are not water-soluble and form a film upon evaporation of the aqueous phase. However, the water did not evaporate quickly enough to form a continuous film on agar because agar is 95% water, and it continuously provided moisture that prevented film formation. The result was a porous barrier, but a continuous film was later obtained by dissolving dried emulsion solids in ethanol. 

In a binary dispersion, there is usually one of five interfaces to consider, where a polysaccharide, for example, may act as a protective colloid. These interfaces are liquid-solid (sol), liquid-liquid (emulsion), solid-solid (mixed xerogel), liquid-air (foam), and solid-air (powder). In any of these systems at... 

The solvent emulsification/evaporation method involves lipid precipitation in O/W emulsions. Solid lipids are dissolved in a water-immiscible organic solvent (e.g., cyclohexane) followed by emulsification in an aqueous medium. Upon evaporation of the solvent, the nanoparticle dispersion is formed due to lipid precipitation. Residue of organic solvents is the major problem of this method [94], However, the microemulsion and solvent emulsification/evaporation methods can be performed conveniently in the laboratory without specific apparatuses. 

As it is well known, the contacts between drops (in emulsions), solid particles (in suspensions) and gas bubbles (in foams) are accomplished by films of different thickness. These films, as already discussed, can thin, reaching very small thickness. Observed under a microscope these films reflect very little light and appear black when their thickness is below 20 nm. Therefore, they can be called nano foam films. IUPAC nomenclature (1994) distinguishes two equilibrium states of black films common black films (CBF) and Newton black films (NBF). It will be shown that there is a pronounced transition between them, i.e. CBFs can transform into NBFs (or the reverse). The latter are bilayer formations without a free aqueous core between the two layers of surfactant molecules. Thus, the contact between droplets, particles and bubbles in disperse systems can be achieved by bilayers from amphiphile molecules. 

Appearance Opaque white emulsion Solids content 55% pH 4.0-5.0... 

Appearance a thin, milky latex emulsion Solids 54% minimum pH 5+-0.5... 

When two surfaces approach each other, two forces exist one repulsive and one attractive. Whether or not the surfaces touch and coalesce depends on the relative sizes of the two forces. This is equally true for liquids (e.g., oil droplets in an emulsion), solids (e.g., finely divided CaCOs), and films (air bubbles in a foam). The description of these interactions is stated in the DLVO theory (8). 

EMULSION IS USUALLY DEFINED as a system consisting of a liquid dispersed with or without an emulsifier in an immiscible liquid, usually in droplets of larger than colloidal sizes. In petroleum emulsions, solids play an extremely important role in both the formation and stability of emulsions. These solids can be oil-phase components such as wax crystals or precipitated asphaltenes, or mineral components that are partially oleophilic, a property that allows them to act as stabilizers between the oil and water phases. 

In this section, we discuss the effects of solids addition on the rheology of oil-in-water emulsions, in particular, the effects of solids size (size distribution) and shape (spherical versus irregular). Because the type of the oil used to form an emulsion is important in determining the viscosity of the oil-in-water emulsion, the rheology of the emulsion-solids mixtures is also influenced by the type of oil. Thus, two distinct emulsion systems with added solids will be discussed (1) synthetic (Bayol-35) oil-in-water emulsions 21, 57) and (2) bitumen-in-water emulsions (58). The synthetic oil has a viscosity of 2.4 mPa s, whereas the bitumen has a viscosity of 306,000 mPa s at 25 C. The Sauter mean diameter of the oil droplets is 10 xm for synthetic oil, and 6 xm for bitumen-in-water emulsions. The synthetic OAV emulsions are fairly shear-thinning, whereas the bitumen OAV emulsions are fairly Newtonian. 

We also discuss the conditions under which emulsions can be considered as a continuous phase toward the added solids, where the prediction of the emulsion-solids viscosity is possible. 

Figure 16. Variation of the viscosity of emulsion-solids mixtures with shear stress at different solids volume fraction. (Reproduced with permission from reference 57. Copyright 1991 Pergamon Press.)...

Effects of Solids Shape. The viscosities of emulsion-solids mixtures are compared when irregular-shaped silica sand and spherical glass beads are added separately to an oil emulsion. The results are shown in Figure 18 for different sizes of glass beads and silica sand for synthetic oil. 

Because the emulsion-solids mixtures are non-Newtonian fluids, a shear stress or a shear rate must be specified when any comparison is made. In Figure 18a, comparison is made between the 22- xm silica sand and the 19- xm glass beads at a shear stress of 6 Pa. The differences in the solids mean diameter and in their size distributions are small. The degree of influence on the viscosity is therefore mainly due to the solids shape. Similar results are... 

Effects of Solids Size. The effect of solids size on the viscosity of the emulsion-solids mixtures is shown in Figure 19 for synthetic OAV emulsions. The oil concentration (solids-free basis) is 60% by volume, and the solids used are silica sand. The comparison is made at shear stresses of 6 and 14 Pa. The viscosity is expressed as the relative viscosity (t7ows/ 7ow)t lhat is, the viscosity of the emulsion-solids mixture divided by the viscosity of the solids-free emulsion. At low solids volume fraction (<0.1), solids size has little effect. 

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