Evaluation of equation‐of‐state parameters from PVT data

Abstract

The characteristic parameters for three different equation-of-state (EOS) theories have been determined for polystyrene and low-molecular weight polyisoprene using pressure-volume-temperature (PVT) data. Basically two procedures for the calculation of characteristic parameters were applied. The characteristic parameters were calculated, firstly, from coeficients of expansion, compressibilities and densities, and secondly, by fitting the corresponding EOS to PVT data minimizing the sum of the squares of the differences between experimental and calculated pressures. The characteristic parameters obtained by the two methods are compared with regard to their ability to describe PVTdata.Acomparison ofthe three different EOS theories reveals that, for describing polymeric liquids, the modified cell model of Dee and Walsh is superior to the theory of Flory, Orwoll and Vrij as well as to the lattice fluid theory of Sanchez and Lacombe. Finally, formulae are given to convert the characteristic parameters from one theory into those of another.

Pressure–volume–temperature dependencies of polystyrenes

“…see [9][10][11][12]. However, the P*, T*, V* values published by various authors for supposedly the same polymer are different.…”

“…In addition Tait empirical relation has been used [8]. Curro [9], Zoller [10], Rodgers [11], Rudolf et al [12], reviewed and evaluated the suitability of several eos to describe the PVT behavior. Of the six mentioned theoretical expressions [11] the two: Dee and Walsh (D-W) modified cell model (MCM) [7], and Simha and Somcynsky (S-S) latticehole theory [4] performed well.…”

Pressure–volume–temperature of molten and glassy polymers

“…Furthermore, the Tait empirical relation for seawater density also has been used 9. Curro,10 Zoller,11 Rodgers,12 and Rudolf et al13 reviewed and evaluated the suitability of several EOS to describe the PVT surface within the liquid state. The Simha–Somcynsky ( S –S) theory4 was found to well describe the PVT dependencies,14–18 as well as to provide good measure of the internal pressure, surface tension, cohesive energy density, or solubility parameters 19, 20.…”

The influence of stereoregularity on the miscibility of poly(propylene)s

“…d is defined through characteristic parameters for EOS theories can be obtained from pressure-volume-temperature (PVT) measurements. 8 In order to quantify the…”

“…8 Graessley et al showed that the SPC can be I. The polymerization procedure using homogeneous metallocene/methylalumoxane catalyst applied successfully in order to describe or predict the miscibility behavior of several binary polysystems was described elsewhere.…”