Ternary Low Molecular Weight Systems

Three component systems are found to exist with various arrangements of phases. The three components may be essentially immiscible and exist as three distinct phases. Consider combining benzene, mercury, and water, which are all immisdble. They will form three layers in order of their inverse density benzene water mercury. If the three components are all totally miscible, they will exist as a single miscible phase. This is the case with aliphatic hydrocarbon mixtures (e.g., hexane, heptane, and octane) under most conditions. Intermediate situations are possible where varying levels of solubility between components widely exist. These often give rise to two phase configurations. One example is when two of the components are fully miscible and both are immiscible with a third component (e.g., benzene and toluene with water as a third component). If the three components have a limited mutual solubility, there will be composition ranges where one, two, or three phases exist and each contains some of each of the components. The classical solution thermodynamics of ternary solutions is implicit in most treatments of chemical thermodynamics (1,2,3]. 

It is useful to consider the thermodynamics of phase equilibrium in ternary regular solutions. Here again we are concerned with 

Consider a regular solution (Section 3.2) that combines together the entropy of mixing for an ideal solution with an endothermic heat of mixing term. The entropy of mixing for a ternary system may be shown to be [4]  

6 Ternary Systems Polymer Blends plus Liquid Additives 

When the ternary solutions exhibit immiscibility, we must be concerned with the conditions for phase equilibrium between the two or three phases. Phase equilibrium in ternary systems is considered in detail in the book by Masing [5]. 

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In this chapter, we have described the behavior of ternary systems. This includes ternary low molecular weight systems (Section 6.2). Polymers with two low molecular weight liquids (Section 6.3) binary polymer blends with a low molecular weight liquid (Section 6.4), binary polymer blends with amphiphilic molecules or block/graft copolymers (Sections 6.5 through 6.7), high impact polystyrene (Section 6.8) and ternary polymer blends (Section 6.9). 

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