Koningsveld-Staverman formalism

To approach AG of quasi-binary polymer solutions in an empirical way it is usual to invoke the Koningsveld-Staverman formalism [5], which chooses the familiar Flory-Huggins (FH) atheimal solution as the reference system and expresses AG as... 

Equation 1.15 may be regarded as the defining equation for the parameter y, since Ago can be evaluated by use of such standard techniques as osmotic pressure, light scattering, and sedimentation equilibrium. In the classic FH theory, y is taken as the strength of the polymer-solvent interaction. However, in the Koningsveld-Staverman formalism, it has no such meaning but is an empirical function which absorbs all the deviations of Ago in an actual quasibinary solution from that in the reference FH solution. 

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