Multiphase separation

under certsuu conditions, 7 phases transform to one phase, such a state of the systems is referred to as the 7-order critical state (or the 7-order critical point) (Kohnstamm, 1926). 

According to Gibbs phase rule (Equation 1.2-32), in a i/-component system with 7 phases, / parameters (such as temperature, pressure, component concentrations) may 

If all the 7 phases turn out to be identical, the number of degrees of freedom in the critical state decreases by (7 — I), so 

The number of degrees of freedom / cannot be negative therefore, for a 7-ordeT critical point to exist, 2-y — 3 components are required at minimum. 

Ilencc, tbc 2nd-order critical point is realized in a one-component system, the 3rd-order one may be observed in a three-component (ternary) system, the 4th-order one — in a five-component system, and so on. 

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Here are some examples of multiphase separation processes. 

Multistage separation Column Generic multiphase separation, including absorber, stripper, rectifia... 

Thus, Equation 14 proves to be valid for multiphase separation as well. 

Figure 3.101. Cloud-poinl curves during multiphase separation (Solcetal., 1984) [Keprinttsl with iwriiiisMioii ftoiii Mattoiiiolecultn 17 (1984) 7 >-085. Copyr Rl - American Chemical Society]...

There are ample books in the literature considering in detail the thermodynamics of polymer solutions, i.e. the state of the P-I-LMWL system above the 9 point (for systems with an upper critical solution temperature) (see the bibliography). With the exception of riory (J953) and Tompa (1956), the other authors cither did not deal with phase separation or mentioned it only in its relation to fractionation. A need has, therefore, arisen to look into the questions of liquid-liquid phase separation (including multiphase separation) as c.arefully as possible, the more so that many applications of these problems can be introduced into the technology of polymer materials. 

The host-guest selectivity of macrocyclic ligands as measured in homogeneous solution can translate effectively into multiphase separations systems such as IC and liquid membranes, even when macrocyclic structures must be modified to accommodate system demands. Separations scientists have applied this selectivity in novel ways to these two methodologies to effect separations that have potential or realized practical uses, both in analytical chemistry and preparative separations. To date, only a fraction of the macrocyclic structures that exhibit such potential have been studied, and to the degree that this line of research is pursued vigorously, many further innovations can be expected. 

Craubner claims - that the perturbation calculus which he has devised is the most successful means of dealing with such phase phenomena thus far. Multiphase Separation. Separation of polymer solutions into more than two liquid phases which coexist in equililnium is known and was predicted by Tompa on the basis of Flory-Huggins theory (see next section). It is one of the success stories in solution thermodynamics that a 3-phase region, so small as to be difficult to find experimentally by chance, was predicted for a polyethylene/ diphenylether system and subsequently confirmed experimentally. ... 

Janik, H., Palys, B., Petrovic, Z. S. (2003), Multiphase-separated polyurethanes studied by micro-Raman spectroscopy, Macromol Rapid. Commun., 24,265-8. 

The description of the extent of separation achieved in a closed vessel for a mixture of molecules is treated in Chapter 1. Chapter 2 illustrates how to describe the separation of molecules in open separators under steady and unsteady state operation a description of separation for a size-distributed system of particles is also included. Chapter 3 introduces various forces developing species-specific veiocities, fluxes and mass-transfer coefficients, and illustrates how the spatial variation of the potential of the force field can develop multicomponent separation ability. The criteria for chemical equilibrium are then specified for different types of multiphase separation systems, followed by an illustration of integrated flux expressions for two-phase and membrane based systems. 

Akins, D. L. Kumar, V. T. High-performance liquid chromatography of cyanine dyes multiphase separation, purification, and substitution of the counter ion. J. Chromatogr., A 1995, 689, 269-273. 

Blending two or above polymers together is an important way to create synergis-tically new physical properties of the composites in the polymer industry. Furthermore, the multiphase separation is produced by polymer blending, and thus, phase morphology of the polymer blends significantly affects the final properties of the composites. When conductive fillers are added to the immiscible polymer blends, the location of conductive fillers in polymer phases may be various and could lead to different electrical properties of CPCs. In another word, conductive fillers can be selectively located in one of the polymer phases or at the phase interfaces [86-88], which can be controlled to constiuct a desirable conductive network structure in CPCs. 

Olvera de la Craz M, Sanchez IC (1986) Theory of multiphase separation in graft and star copolymers. Macromolecules 19 2501-2508... 

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