Models for residual chemical potential and activity coefficient in the liquid phase

1 Models for residual chemical potential and activity coefficient in the liquid phase 

Since polymer solutions in principle do not Mfill the rules of the ideal mixture but show strong negative deviations from Raoult s law due to the difference in molecular size, the athermal Flory-Huggins mixture is usually applied as the reference mixture within polymer solution thermodynamics. Starting from Equation [4.4.11] or from 

The total solvent activity/activity coefficient/chemical potential is simply the sum of the athermal part as given above, plus a residual contribution  

The residual part has to be explained by an additional model and a number of suitable models is now listed in the following text. 

The Flory-Huggins interaction function of the solvent is the residual function used first and is given by Equations [4.4.12 and 4.4.13] with / RT = It was originally 

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