COR-eos and BH-eos parameters for polymer melts with the error in the all-variables method
✍ Scribed by Christian Wohlfarth
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 778 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
All the data for more than 100 polymer melts in a PVT data base were used to determine best-fit characteristic parameters for two different theoretical equations-of-state (eos) : the chain-of-rotators (COR) and the Bruce Hartmann (BH) eos. Fitting was performed by applying an error in all-variables algorithm that was recently developed by Hartmann et al. Despite their very different theoretical basis, both equations-of-state led to close descriptions of the PVT surface with comparable average deviations. 0 1993 John Wiley & Sons. Inc. ---l + Z . B ( F ) , RT* 2 ( 3 ) Chien et al.55 adjusted the empirical coefficients A,,
and Bi to the PVT data, internal energies, and vapor pressure data of methane, ethane, and propane. These coefficients are considered to be "universal" constants for all our calculations in this work. Finally, three parameters remain in the COR-eos, i.e., Vo, c , and T*, which must be fitted to experimental PVT data (which is the special aim of this work).
Originally, the COR-eos was not thought to be applicable to polymer melts. Its main purpose was the calculation of phase equilibria in solvent mixtures. Regener et a1.58r59 also proved the COR-eos to be useful for phase equilibrium calculations in polymer solutions. Wohlfarth and co-workers applied the COR-eos to high-pressure phase equilibria in monomer /polymer mixtures!' As all these calculations are rather sensitive with respect to the characteristic parameters of the pure components, the error in the all-variables-fit procedure now provides more accurate parameters for this task.