Hildebrand solubility parameter group contribution methods

The Hildebrand solubility parameters may be calculated using group contribution methods, wherein the overall solubility parameter is the sum of contributions from Van derV feals dispersion forces, Sd dipole-dipole interaction and hydrogen bonding. 

The first two terms represent the combinational entropy of mixing. Since these entropy terms are usually small in polymer blends, AG, is dominated by the balance between the third and fourth terms. The third term represents physical forces that can be estimated using Hildebrand s approach from solubility parameters calculated using group contribution methods for a set of carefully chosen groups which are free from association (see also Section 2.1.6) [8,15]. The fourth term represents the favorable hydrogen-bonding contribution to AG - Its... 

Traditionally, solubility parameters are given in (cal cm ) = Hild(ebrands), in honour of the founder of the regular solution theory, Joel Hildebrand. The solubility parameters were originally defined in conjunction with the regular solution theory. Now, they are more commonly listed in (MPa) (= (J cm ) ). In the absence of experimental data, the solubility parameters of both solvents and polymers can be estimated via group contribution methods, as discussed by van Krevelen and Hoftyzer (1972). 

Also, the original Hildebrand approach has been refined to take into account the contribution of polar groups and hydrogen bsolubility parameters. These mndifications of the Flory-Huggins theory and of the solubility parameter concept have made these methods an even more useful tool in the description of solutions, especially of mixtures containing polymer compounds. A comprehensive treatment of these extensions of Flory-Huggins and Hildebrand s theories, as well as the new equation of state approach of Flory (1965), bns re ntly been published (Shinoda, 1978 Olahisi et al 1979). 

Solubility parameter theory was advanced first by Hildebrand and Scott. Small developed a method for calculating the parameters from the contributions of groups within the molecule. Bunell, Hansen, and Crowley et al. were especially successful in utilizing the concept for the formulation of solvent-based... 

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