Critical properties of homopolymer fluids studied by a Lennard-Jones statistical associating fluid theory
Title:
Critical properties of homopolymer fluids studied by a Lennard-Jones statistical associating fluid theory
Author:
PAMIES, JOSEP C. VEGA, LOURDES F.
Appeared in:
Molecular physics
Paging:
Volume 100 (2002) nr. 15 pages 2519-2529
Year:
2002-08-10
Contents:
A Lennard-Jones statistical associating fluid theory, the soft-SAFT equation of state, is used to study the dependence of the critical properties on chain length for pure polymers. The critical constants of chains up to 106 monomer units are predicted. The main advantage of these calculations, versus others found in the literature, is the fact that the equation is able to accurately predict experimental data available only for short chain lengths and, at the same time, it is able to predict the critical properties in the infinite chain length scaling regime, without any further assumptions. The equation gives quantitative agreement with experimental and Monte Carlo simulation data for normal alkanes. For very long chains, the equation predicts mean-field scaling behaviour, as expected. Moreover, taking advantage of the linearity of the molecular volumes and dispersive energies with the chain molecular weight, a value of 1/5 is found for the critical compressibility factor of an infinitely long n-alkane chain. It is demonstrated that this is not contradictory to Wertheim's theory.
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