Development of a Predictive Equation of State for Solvents,

Monomers, and Polymers

Walter G. Chapman, Rice University, Houston, TX  USA

Engineers need a tool to confidently extrapolate available phase

equilibria data or to predict phase behavior when data is lacking.

Several recent advances in statistical mechanics have led to

accurate equations of state for associating polyatomic fluids that

are beginning to meet this need.  These advanced equations of state

enable engineers to predict the effects of molecular weight,

polydispersity, polarity, intermolecular association, and

compressibility on the phase behavior of mixtures containing

solvents, monomers, and polymers.

One of the most successful of these equations of state is the

statistical associating fluid theory (SAFT).  SAFT is based on

extensions and simplifications of Wertheim's thermodynamic

perturbation theory for associating fluids.  In this seminar, we

briefly review the physical basis for the SAFT approach and discuss

the strengths and weaknesses of the equation of state.  An advantage

of theoretically based equations of state is that the theory can be

systematically extended to more complex fluid systems.  These points

are illustrated through comparisons with phase equilibria data for

monomers, solvents, and copolymer systems.