The Theory of Rubber Swelling

The seminal work of Flory and Rehner [1-3] set the framework for analysis of swollen polymer gels. In their approach it is assumed that in a crosslinked rubber at equilibrium the free energy of mixing and the change in elastic component are separable and additive. The chemical potential change on dissolution at equilibrium is written as  

The mixing term can be expressed using the liquid-lattice theory of Flory and Huggins [4, 5] as  

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