The name is absent

to provide an accurate description of the phase behavior of polymer solutions for the
whole range of polymer weight fractions, as pointed out by Gross and Sadowski [48].
They found that the EOS significantly underestimated the cloud point pressure of
polymer solutions at polymer concentrations greater than 10wt.%. This is significant
since the polymer concentration in systems of industrial interest is typically between
10 and 20wt.%.

As evident from previous discussion, all variants of the SAFT including PC-SAFT
have used the chain term originally proposed by Chapman et al. [46, 47]. Hence, a
possible reason for the inaccuracy in polymer phase behavior prediction is inaccu-
racy in this chain term. The chain term was developed from Wertheim’s theory for
associating fluids by forcing spheres to bond, to form a mixture of chain fluids. For
hard chain fluid, although the results are in good agreement with molecular simula-
tion results, the SAFT-HS EOS becomes less accurate as the molecular chain length
increases [47, 80]. Ghonasgi and Chapman [80], and independently Chang and San-
dler [81], demonstrated that a SAFT Dimer EOS for hard-chain fluids, created by
bonding hard-sphere dimers (or diatomics) together to form chain-like molecules is in
excellent agreement with molecular simulation results for long chain molecules [80].

In this work, a new EOS for real fluids based on the SAFT Dimer hard-chain term
has been proposed. The new EOS, labeled as SAFT-D, describes the phase behav-
ior of polymer solutions accurately over the whole range of polymer concentrations.
Moreover, a better representation of the coexistence curves for long chain molecules

36

<<   45   46   47   48   49   50   51   >>

More intriguing information