Figure 2.10: Vapor phase compositions of long chain alkanes for the systems in fig-
ures 2.8b, 2.9a, and 2.9b. Comparison of the predictions from the new equation of state
(solid lines) and PC-SAFT (dashed lines) with experimental data from Joyce et. al. [89, 90].
extrapolated parameters can predict HDPE densities with reasonable accuracy along
with predicting better phase behavior for HDPE-pentane system than PC-SAFT. As
pointed out by Gross and Sadowski [79], extrapolated parameters do not account for
high molecular effects such as entanglement, and shielding which are not observed
in lower n-alkanes. Hence, the obtained parameters were modified slightly along
with kij∙, to obtain a better fit for the phase behavior of HDPE-n-pentane system.
Finally, the parameters for HDPE were fixed at m∕Mw = 0.02361, σ = 4.4357Â, and
e∕k = 278.78 K. The parameters give better agreement for the density data of HDPE
in the previous pressure and temperature range, with an average absolute deviation
of 3.74%. The solid curve in figure 2.11a also shows the phase behavior of HDPE-
pentane using these parameters in a cloud point pressure versus polyethylene (PE)
56