Concentration space ternary mixture

Figure 2.13b shows a structure of concentration space of mixture benzene (entrainer) (1) -isopropyl alcohol(2)-water(3). The mixture has a ternary azeotrope and three binary azeotropes. 

The (n - 1) concentration for an n-component mixture can be fixed independently because concentration of the nth component can be found from Eq. (1.2). That is why the dimensionality of the concentration space of binary mixture Ci is one, of ternary mixture C3 - two, of four-component mixture C4 - tree, etc. 

The binary eutectics are represented by points A (31.5 °C 72.5 per cent O, 27.5 per cent M), B (33.5 °C 75.5 per cent O, 24.5 per cent M) and C (61.5 °C 54.8 per cent M, 45.2 per cent P). Curve AD within the prism represents the effect of the addition of the component P to the 0-M binary eutectic A. Similarly, curves BD and CD denote the lowering of the freezing points of the binary eutectics B and C, respectively, on the addition of the third component. Point D, which indicates the lowest temperature at which solid and liquid phases can coexist in equilibrium in this system, is a ternary eutectic point (21.5 °C 57.7 per cent O, 23.2 per cent M, 19.1 per cent P). At this temperature and concentration the liquid freezes invariantly to form a solid mixture of the three components. The section of the space model above the freezing point surfaces formed by the liquidus curves represents the homogeneous liquid phase. The section below these surfaces down to a temperature represented by point D denotes solid and liquid phases in equilibium. Below this temperature the section of the model represents a completely solidified system. 

Copolymers can be mixed with other copolymers, homopolymers, or solvents. Broadly speaking, there are three general problems related to the phase behavior of these blends the microphase behavior, the interplay between microphase and macrophase separation, and micelle formation at low copolymer concentration. The mixtures sometimes form one phase, which can be either ordered or disordered, and sometimes they separate into two macrophases. In the latter case, each of the macrophases can be ordered or disordered. For example, there could be coexisting phases of spheres and cylinders. The phase behavior of a two component system can be summarized by a temperature-composition phase diagram [102,103], that of a three component system by a series of ternary phase diagrams, and so on. Space permits touching only briefly on a small sample of these possibilities in this chapter. Copolymers can also be used as surfactant in homopolymer-homopolymer blends, but that topic is beyond the scope of this chapter. 

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