W. Wang et al., A COMPARISON OF LATTICE FLUID MODELS FOR THE CALCULATION OF THE LIQUID-LIQUID EQUILIBRIA OF POLYMER-SOLUTIONS, Fluid phase equilibria, 114(1-2), 1996, pp. 47-62
The group contribution lattice-fluid equation of state (GCLF) has been
compared to the Sanchez-Lacombe (S-L) equation of state and experimen
tal data for liquid-liquid equilibrium in polymer-solvent systems. Bot
h equations of state are shown to be capable of predicting upper criti
cal solution temperatures, lower critical solution temperatures, simul
taneous upper and lower critical temperatures and ''hour glass'' behav
ior in which there is no upper or lower critical temperature. The pred
ictions of the GCLF model and S-L model are compared to systems which
show a LCST and both a LCST and UCST. The specific systems studied inc
lude: acetic acid/dodecane, polyisobutylene/n-pentane, polyethylene/n-
hexane, polystyrene/n-hexane, polyisobutylene/n-pentane, and polystyre
ne/acetone. The GCLF showed good agreement with the experimental data
for systems with a LCST. In all cases the GCLF model performed better
than the S-L model. The GCLF showed good sensitivity to the molecular
weight of the polymer, but failed to show the needed sensitivity to pr
essure. The enhanced performance of the GCLF model was attributed to u
sing saturated vapor and liquid properties simultaneously to regress t
he group parameters for the model.