Thermodynamics and Solubility Parameters

Modifications have been suggested to improve these models to describe the thermodynamics of polymer-polymer miscibility (Huggins, 1942 Flory, 1965 McMaster, 1973 Patterson and Robard, 1978). 

An alternate approach, which starts from blends and evaluates their interaction parameters, is the use of the Hildebrand Solubility Parameter concept (Hildebrand and Solubility, 1964 Gee, 1942, 1947). This has been used for solvent-solvent miscibility as well as for polymer-solvent mixing because it provides a more intuitive approach to predicting miscibility of polymers with solvents including solutions and gels such as swelling of vulcanized rubbers in organic liquids. Both of the models have similar deficiencies in themselves that they do not account for equation of state effects, and a consideration of speeific interactions can be added only as perturbation to these models. 

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