COMPARISON OF SANCHEZ-LACOMBE AND SAFT MODEL IN PREDICTING SOLUBILITYOF POLYETHYLENE IN HIGH-PRESSURE FLUIDS

Sanchez-Lacombe and SAFT (statistical associating fluid theory) models are used to describe phase behavior of polyethylene solutions (M(w) = 2,150, 16,400, 108,000, and 420,000, and M(w)/M(n) = 1.14, 1.16, 1.32 , and 2.66, respectively) in n-pentane and in n-butane at high pressur es. In order to test the predictive capability of the two models, all the predictions were conducted without any adjustment of the binary in teraction parameter. Even though both models correctly predict the gen eral trends of the phase envelopes and the LCST (lower critical soluti on temperature) nature of the systems. SAFT gives predictions that are much closer to the experimental data than the Sanchez-Lacombe model. (C) 1995 John Wiley and Sons, Inc.