Flory-Huggins rigid-lattice model

In addition to the Flory-Huggins rigid-lattice model, the development of the thermodynamics of polymer... 

Thermodynamic descriptions of polymer systems are usually based on a rigid-lattice model published in 1941 independently by Staverman and Van Santen, Huggins and Flory where the symbol x(T) is used to express the binary interaction function [16]. Once the interaction parameter is known we can calculate the liquid liquid phase behaviour. 

The calculation of the entropy of mixing, ASm, of polymers in solution was carried out by Flory (3) and Huggins (4) in 1942. The Flory-Huggins (FH) theory, based on the rigid lattice model developed for solutions of small molecules, leads to the following expression for the free energy of mixing ... 

Flory-Huggins theory (Flory, 1941, 1942, 1945 Huggins, 1941, 1942abc, 1958 Tompa, 1956 Volkenshtcin, 1959 Casassa, 1976, 1977) is based on a model of a rigid lattice of m cells, whose volume i i is commensurable to that of the LMWL molecule. The lattice with the coordination number u contains m2 macromolecules and m LMWL molecules. Each macromolecule is composed of z fragments (segments), each occupying one cell of the lattice ... 

Like the Flory-Huggins model, the Sanchez-Lacombe lattice fluid theory is based on the assumption that segments of solvent molecules and polymer molecules occupy the lattice sites of a rigid lattice, but vacant lattice sites are also allowed. The number of vacant lattice sites, and as a consequence the total number of lattice sites, are pressure-dependent, and in this way compressibility is introduced. 

---