Thermodynamics of paint-related systems with engineering models

Paints are complex materials composed of polymers (binders) dissolved in on e or more solvents, pigments, and other additives. The thermodynamics of su ch systems is essential, for example, for selecting improved solvents and u nderstanding a number of phenomena related especially! to adhesion to solid surfaces and drying. Many engineering models have been applied over the la st decades for solutions with commoditity polymers. In this work the perfor mance of some of these models is investigated for paint-related systems, fo cusing on those drying by the so-called " lacquer mechanism " (evaporation of solvents). These are the Entropic-FV UNIFAC-FV, GC-Flory, and the Flory- Huggins models using various ways for estimating the FH parameter via solub ility, parameters. Achievements and shortcomings of these models are discus sed in conjunction with difficulties encountered in such calculations. We c onclude that, despite the uncertainties involved, several models yield reas onably accurate activity coefficients, even at infinite dilution. Thus, eng ineering models may be useful for solvent selection via semiempirical rules of thumb, which are based on thermodynamic considerations.