Stabilization surfactants

One may rationalize emulsion type in terms of interfacial tensions. Bancroft [20] and later Clowes [21] proposed that the interfacial film of emulsion-stabilizing surfactant be regarded as duplex in nature, so that an inner and an outer interfacial tension could be discussed. On this basis, the type of emulsion formed (W/O vs. O/W) should be such that the inner surface is the one of higher surface tension. Thus sodium and other alkali metal soaps tend to stabilize O/W emulsions, and the explanation would be that, being more water- than oil-soluble, the film-water interfacial tension should be lower than the film-oil one. Conversely, with the relatively more oil-soluble metal soaps, the reverse should be true, and they should stabilize W/O emulsions, as in fact they do. An alternative statement, known as Bancroft s rule, is that the external phase will be that in which the emulsifying agent is the more soluble [20]. A related approach is discussed in Section XIV-5. 

Colloidal Stabilization. Surfactant adsorption reduces soil—substrate interactions and faciUtates soil removal. For a better understanding of these interactions, a consideration of coUoidal forces is required. 

There are special shale stabilizing surfactants consisting of nonionic alkanol-amides [900, %2], for example, acetamide monoethanolamines and diethanolamines. 

Oil-in-water emulsions provide a cost-effective alternative to the methods mentioned previously, namely, heating or diluting. A typical transport emulsion is composed of 70% crude oil, 30% aqueous phase, and 500 to 2000 ppm of a stabilizing surfactant formulation [1497]. Nonionic surfactants are relatively insensitive to the salt content of the aqueous phase ethoxylated alkylphenols have been used successfully for the formation of stable emulsions that resist inversion. 

M. Jarrett. Nonionic alkanolamides as shale stabilizing surfactants for aqueous well fluids. Patent WO 9632455, 1996. 

Uses Manufacture of triethylenemelamine and other amines fuel oil and lubricant refining ion exchange protective coatings adhesives pharmaceuticals polymer stabilizers surfactants. 

In this situation, the equilibrium thickness at any given height h is determined by the balance between the hydrostatic pressure in the liquid (hpg) and the repulsive pressure in the film, that is n = hpg. Cyril Isenberg gives many beautiful pictures of soap films of different geometries in his book The Science of Soap Films and Soap Bubbles (1992). Sir Isaac Newton published his observations of the colours of soap bubbles in Opticks (1730). This experimental set-up has been used to measure the interaction force between surfactant surfaces, as a function of separation distance or film thickness. These forces are important in stabilizing surfactant lamellar phases and in cell-cell interactions, as well as in colloidal interactions generally. 

Macromonomers afford a powerful means of designing a vast variety of well-defined graft copolymers. These species are particularly useful in the field of polymer blends as compatibilizers and/or stabilizers (surfactants). When macromonomer itself is an amphiphilic polymer, then its polymerization in water usually occurs rapidly as a result of organization into micelles. In copolymerizations, important factors for macromonomer reactivity are the thermodynamic repulsion or incompatibility between the macromonomer and the trunk polymer and its partitioning between the continuous phase and the polymer particles [4,5]. 

One useful method of aqueous defoaming is to add a nonfoam stabilizing surfactant which is more surface-active than the stabilizing substance in the foam. Thus a foam stabilized with an ionic surfactant can be broken by the addition of a very surface-active but nonstabiliz-ing silicone oil. The silicone displaces the foam stabilizer from the interface by virtue of its insolubility. However, it does not stabilize the foam because its foam films have poor elasticity and rupture easily. 

One kind of surface emulsion that is desirable is the Orinoco bitumen emulsion produced from in situ steam stimulation and recovery in the Orinoco River deposit in Venezuela. This emulsion is reformulated into Orimulsion , an O/W emulsion, containing about 30% fresh water and a stabilizing surfactant (typically about 0.1 percent each of monoethanolamine and an alcohol ethoxylate) [588,759,760], The O/W emulsion has a viscosity of about 450 mPa-s (30 °C, 100 s-1) compared with the original bitumen viscosity of about 10000 mPa-s [760,761], This emulsion can be used as an alternative fuel for power-generating plants. Being water-continuous the emulsion is easily handled and transported, but otherwise behaves similarly to fuel oil. 

A foam that, in addition to the stabilizing surfactants, contains polymer and a cross-linking agent. The foam is first generated as a polymer-thickened foam, and after a delay period, gels. See also Stiff Foam. 

The epoxy-PVC plastisol type is a mixture of a plastisol-grade PVC powder, primary PVC plasticizers (e.g., dioctyl phthalate), a liquid DGEBA epoxy resin, thickeners, stabilizers, surfactants, and other additives. The epoxy serves as a secondary plasticizer, acts as a stabilizer (acid scavenger), and helps to fortify the plastisol by crosslinking during cure. 

Classes a and b imply the requirement of a covalently bonded, non-diffusible protective layer to achieve F/T stability, whereas Class c involves either a freezing-point lowering (glycols, salts) or additional stabilization (surfactants), presumably in emulsions already moderately stable to freezing and thawing. 

Sorbitan sesquioleate Base, emulsifying agent, solubilizing agent, stabilizer, surfactant, vehicle iv, im... 

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