Some Limitations of the Flory-Huggins Theory

In spite of its limitations, some of which are listed in the box below, the Flory-Hug- 

FIGURE 11-26 Experimental phase diagram of polystyrene of different molecular weights in acetone [redrawn from the data of Siow, Delmas and Patterson. Macromolecules, 5,29 (1972)1. 

Is based on a lattice model that uses various approximations in the counting process. 

It ignores free volume and only accounts for combinatorial entropy, 

It assumes random mixing of chains in calculating the entropy and segments in calculating the enthalpy. 

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