Pseudoemulsion film model

Pseudoemulsion Film Model. Although much attention is traditionally focused on foam lamellae, the thin liquid films bounded by gas on each side and denoted as air—water—air (A/W/A), a distinct but related thin liquid film, may be the most important for foam stability in the presence of oil. That is, the thin liquid films bounded by gas on one side and by oil on the other denoted air—water-oil (A/W/O). These films are illustrated in Figure 6a—6c. They are also referred to as pseudoemulsion films (48). Their importance stems from the fact that it is possible for the pseudoemulsion film to be metastable in a dynamic system, even when the thermodynamic entering coefficient is greater than zero. 

A single model of foam-oil interaction cannot account for all situations. Certain foam—oil sensitivity models can be reconciled with both microvisual studies and core-flood foam effectiveness measurements, all for a wide variety of foams, oils, porous media, and other experimental conditions. However, exceptions are readily found. In an earlier section, the models of emulsification—imbibition, pseudoemulsion film thinning, entering, and spreading were introduced. Cases in favor of, and exceptions to, the applicability of each of these can be found in the literature. Although this situation prompts some inclination to search for additional mechanisms, the truth may be that all the models presented have some validity and that one or another valid mechanism is most significant in a given situation. 

The thin liquid films bounded by gas, on one side, and by oil, on the other side, denoted air-water-oil (A/W/O) or oil-water-air (O/W/A) are referred to as pseudoemulsion films [58]. They are important because the pseudoemulsion film can be metastable in a dynamic system even when the thermodynamic entering coefficient is greater than zero. Several groups [58, 70, 107] have interpreted foam destabilization by oils in terms of pseudoemulsion film stabilities [65]. This is done based on disjoining pressures in the films, which may be measured experimentally [105], or calculated from electrostatic and dispersion forces [107]. The pseudoemulsion model has been applied to both bulk foams and foams flowing in porous media. 

FIG. 32 Scanning laser microscopic reflection features of pseudoemulsion films from the model foaming solution (60 mM SDS/0.5 wt.% PVA) for the silicone oU antifoams (A series) and the mixed-type antifoams (B series). Estimated images of vertical sectional views are shown under these features. 

Fig. 33 illustrates the SLM reflection features of the pseudoemulsion films from the model foaming solution formed on the top of the hydrophobic silica antifoams (C series) and the silicone resin antifoams (D series). Estimated images of the vertical sectional views are also shown under these SLM features. It is seen that the pseudoemulsion films were confirmed on the top of their particles when the thickness of the surfactant solutions was slightly... 

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