The closed-loop coexistence curves of liquid-liquid equilibria were calculated by decorated-UNIQUAC model, incoporating the decorated lattice and UNIQUAC model. The applicability of decorated-UNIQUAC model to the polymer solution, the salt solution and polymer blend systems was tested by adding appropriate concepts.
For PEG-water systems, closed-loop diagrams were calculated by correcting the over-estimated size factor in decorated-UNIQUAC on the basis of the blob rescaling concept. The blob size, which depends on not only the solution states but also the chain properties of the polymer, varies along with rigidity of polymer chain. For various molecular weights of PEG, the calculated results showed good agreements in the size and shape of phase diagrams.
For salt solution systems, the effects of ionic forces were considered as a form of the chemical theory in addition to decorated-UNIQUAC model. The closed-loop diagram of tetra-n-butylammonium thiocyanate-water system was also calculated.
In the PMMA-PC blend systems, closed-loop diagrams were also caluculated by correcting the over-estimated structural parameter on the basis of blob rescaling concepts, and the proposed method fairly reproudced the size and shape of the region of phase separations.