Binodes: definition

The thermodynamic definition of the spinodal, binodal and critical point were given earlier by Eqs. (9), (7) and (8) respectively. The variation of AG with temperature and composition and the resulting phase diagram for a UCST behaviour were illustrated in Fig. 1. It is well known that the classical Flory-Huggins theory is incapable of predicting an LCST phase boundary. If has, however, been used by several authors to deal with ternary phase diagrams Other workers have extensively used a modified version of the classical model to explain binary UCST or ternary phase boundaries The more advanced equation-of-state theories, such as the theory... 

These nets arc by definition at least binodal, and the pts net was treated in Chapter 5. We will look at three more of these nets here. 

One more effect should be taken into account. Because the miscibility of two species depends on the ratio of their molecular mass, the situation arises where, on the change of the outer conditions, the system remains in a thermodynamically stable state for some fractions of definite molecular mass, while already undergoing the phase separation for other fractions. Although this point has practically not been dealt with in the hterature, its role in the formation of a non-equilibrimn frozen structure should be essential. It means that the state of a system turns out to be dependent on its history. Thus, again, the phase diagram by itself yields a poor indication of the system state within the region of immiscibility bomid by the spinodal or binodal curve. 

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