Three-phase diagram

The three phase diagrams, or parts of diagrams, shown in Fig. A1.28, all have a eutectic point. Mark the point with an arrow and list the eutectic temperature and composition in wt% (the co-ordinates of the point). 

In 1959, J. H. Schulman introduced the term microemulsion for transparent-solutions of a model four-component system [126]. Basically, microemulsions consist of water, an oily component, surfactant, and co-surfactant. A three phase diagram illustrating the area of existence of microemulsions is presented in Fig. 6 [24]. The phase equilibria, structures, applications, and chemical reactions of microemulsion have been reviewed by Sjoblom et al. [127]. In contrast to macroemulsions, microemulsions are optically transparent, isotropic, and thermodynamically stable [128, 129]. Microemulsions have been subject of various... 

Fig. 6 Three-phase diagram illustrating the area of existence of microemulsions. (From Ref. 24.)...

FIGURE 7.3 Hypothetical three-phase diagram of surfactant/oil/water composition illustrating the rapid change in the constitution as a microemulsion phase is diluted in water. 

Figure 1. Part of the three phase diagrams of [C (EO -decane-water] for 6 temperatures.

Figure 2. Part of the three-phase diagram of the C CEOJ -decane-water system. isotropic inverse micelle phase N liquid...

Absolute alcohol is required for the production of gasohol. Figure E4-1 shows a three-phase diagram of gasoline-ethanol-water. Notice how just a small amount of water can make the gasoline divide into two phases. 

Figure 5. A three phase diagram for C02 (Reproduced with permission from reference 14. Copyright 1986 Canadian Institute of Mining Metallurgy, and Petroleum.)...

A number of alternative ways are available for indicating the equilibrium in a system of nonstoichiometric composition. For a binary system, for example, there are the following three phase diagrams ... 

Fig. 1. A schematic representation of the pseudo three-phase diagram of surfactant/cosurfactant-oil-water systems (a) oil-in-water microemulsion (b) water-in-oil microemulsion (o) bicontinuous structure (d) lamellar structure and (e) conventional two-phase emulsion.

The SANS technique was further adopted to study the partitioning of monomer between microemulsion droplets and polymer particles for various monomers (ST, w-butyl methacrylate, -butyl methacrylate, and CeMA) (34). It was found that, during microemulsion polymerization, the partitioning of monomer is strongly dependent on the composition of microemulsion, especially on the distance to the phase boundary in the pseudo three-phase diagram of the surfactant/cosurfactant-oil-water system. For example, the monomer partitioning is linear in nature and the concentration of monomer in polymer particles is quite low if the initial microemulsion composition is far away from the phase boundary. In contrast, the monomer partitioning is essentially nonlinear and the... 

Near the cosurfactant (co) corner the changes are small compared with the three-phase diagram (Figure 10.4). The O/W microemulsion near the water-surfactant (sa) axis is not in equilibrium with the lamellar phase, but with a non-colloidal oil + cosurfactant phase. 

Air-cathode composition showing the structure and functions of each component, (b) Three-phase diagram for the oxygen-reduction process in the aqueous electrolyte. 

Figure A2.5.31. Calculated TIT, 0 2 phase diagram in the vicmity of the tricritical point for binary mixtures of ethane n = 2) witii a higher hydrocarbon of contmuous n. The system is in a sealed tube at fixed tricritical density and composition. The tricritical point is at the confluence of the four lines. Because of the fixing of the density and the composition, the system does not pass tiirough critical end points if the critical end-point lines were shown, the three-phase region would be larger. An experiment increasing the temperature in a closed tube would be represented by a vertical line on this diagram. Reproduced from [40], figure 8, by pennission of the American Institute of Physics.

The accompanying sketch qualitatively describes the phase diagram for the system nylon-6,6, water, phenol for T > 70°C.f In this figure the broken lines are the lines whose terminals indicate the concentrations of the three components in the two equilibrium phases. Consult a physical chemistry textbook for the information as to how such concentrations are read. In the two-phase region, both phases contain nylon, but the water-rich phase contains the nylon at a lower concentration. On this phase diagram or a facsimile, draw arrows which trace the following procedure ... 

Nevertheless, possibiUties for confusion abound. From the definitions of microemulsions and macroemulsions and from Figure 1, it immediately follows that in many macroemulsions one of the two or three phases is a microemulsion. Until recentiy (49), it was thought that all nonmultiple emulsions were either oil-in-water (O/W) or water-in-oil (W/O). However, the phase diagram of Figure 1 makes clear that there are six nonmultiple, two-phase morphologies, of which four contain a microemulsion phase. These six two-phase morphologies are oleic-in-aqueous (OL/AQ, or O/W) and aqueous-in-oleic (AQ/OL, or W/O), but also, oleic-in-microemulsion (OL/MI), microemulsion-in-oleic (MI/OL), aqueous-in-microemulsion (AQ/MI), and microemulsion-in-aqueous (MI/AQ) (49). 

Even at the lowest temperatures, a substantial pressure is required to soHdify helium, and then the soHd formed is one of the softest, most compressible known. The fluid—soHd phase diagrams for both helium-3 and helium-4 are shown in Eigure 1 (53). Both isotopes have three allotropic soHd forms an fee stmeture at high pressures, an hep stmeture at medium and low pressures, and a bcc stmeture over a narrow, low pressure range for helium-4 and over a somewhat larger range for helium-3. The melting pressure of helium-4 has been measured up to 24°C, where it is 11.5 GPa (115 kbar) (54). 

Fig. 3. Phase diagram for helium-3 where A, B, and A1 represent the three superfluid phases and PCP is the polycritical poiat. The dashed lines iadicate the...

Fig. 6. Phase diagram for three crystalline and two Hquid forms of phosphoms(V) oxide. To convert kPa to mm Hg, multiply by 7.5.

For sodium palmitate, 5-phase is the thermodynamically preferred, or equiUbrium state, at room temperature and up to - 60° C P-phase contains a higher level of hydration and forms at higher temperatures and CO-phase is an anhydrous crystal that forms at temperatures comparable to P-phase. Most soap in the soHd state exists in one or a combination of these three phases. The phase diagram refers to equiUbrium states. In practice, the drying routes and other mechanical manipulation utilized in the formation of soHd soap can result in the formation of nonequilibrium phase stmcture. This point is important when dealing with the manufacturing of soap bars and their performance. 

Glassification of Phase Boundaries for Binary Systems. Six classes of binary diagrams have been identified. These are shown schematically in Figure 6. Classifications are typically based on pressure—temperature (P T) projections of mixture critical curves and three-phase equiHbria lines (1,5,22,23). Experimental data are usually obtained by a simple synthetic method in which the pressure and temperature of a homogeneous solution of known concentration are manipulated to precipitate a visually observed phase. 

The Class I binary diagram is the simplest case (see Fig. 6a). The P—T diagram consists of a vapor—pressure curve (soHd line) for each pure component, ending at the pure component critical point. The loci of critical points for the binary mixtures (shown by the dashed curve) are continuous from the critical point of component one, C , to the critical point of component two,Cp . Additional binary mixtures that exhibit Class I behavior are CO2—/ -hexane and CO2—benzene. More compHcated behavior exists for other classes, including the appearance of upper critical solution temperature (UCST) lines, two-phase (Hquid—Hquid) immiscihility lines, and even three-phase (Hquid—Hquid—gas) immiscihility lines. More complete discussions are available (1,4,22). Additional simple binary system examples for Class III include CO2—hexadecane and CO2—H2O Class IV, CO2—nitrobenzene Class V, ethane—/ -propanol and Class VI, H2O—/ -butanol. 

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