A study of the demixtion curve for finite

Let us now examine the shape of the demixtion curve for small values of p (dilute and semi-dilute solutions). In this case, we have 

The law of equal areas (Maxwell s rule) which defines the demixtion curve can be expressed as follows [see Appendix L, eqns (L.1) and (L.5)] 

This set of equations can be solved in parametric form, the parameter being t = ip /tp1 with 0 t qo. The representation is the following 

In this way, we obtain a universal curve which is represented in Fig. 14.16. We observe that the top of the curve is parabolic. In fact, eqns (14.5.6) show that in the vicinity of this point 

Let us now examine the low temperature behaviour (t 1). Equations (14.5.6) shows that in this case 

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