Flory—Huggins theory entropy changes

What is the change in entropy of mixing, according to the Flory-Huggins theory Explain and write the equation. 

The basis for phase separation in polymer blends must be considered further here. For the Flory-Huggins theory of incompressible polymer mixtures (see Section 3.3), the small entropy of mixing is dominated by the heat of mixing, leading to the conclusion that the heat of mixing must be zero or negative to induce miscibility. When the system is compressible, the reverse may be true. Compressible in the current sense means that the theory includes terms for volume changes. 

The entropy and enthalpy change on mixing are, according to the modified Flory-Huggins theory, given by ... 

Nonideal thermodynamic behavior has been observed with polymer solutions in which A Hm is practically zero. Such deviations must be due to the occurrence ofa nonideal entropy, and the first attempts to calculate the entropy change when a long chain molecule is mixed with small molecules were due to Flory [8] and Huggins [9]. Modifications and improvements have been made to the original theory, but none of these variations has made enough impact on practical problems of polymer compatibility to occupy us here. 

At about 55 % the slope of the Ago curve shows a sudden change. This indicates the occurrence of a polymer-solvent compound with 6 molecules acetone per glucose-unit, in conformity with X-ray investigations It is to be noted in this connection, that the entropy of mixing in the system cellulose nitrate-acetone becomes negative in the limit of very low concentrations of acetone. This is explained by Schulz on the assumption that the solvent molecules are absorbed by the cellulose nitrate on to localised sites (perhaps in an orientated state), to which one would have to attribute a lower entropy. A behaviour of this type is, of course, not accounted for in Huggins and Flory s theory of the entropy of mixing. 

Parameters related to differences in size and shape and respectively change in internal energy of mixing Entropy correction terms Parameter related to average interaction energy Internal energy of the system Flory s equation of state Flory-Huggins Staverman theory... 

A quantitative theory of the change in conformational entropy produced by the mixing of flexible chain polymers with a solvent of low molecular weight was formulated by Flory [3] and Huggins [4],... 

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