1999 Volume 32 Issue 5 Pages 611-618
PVT data are measured for ten fractionation cuts of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) at temperatures (298–338) K and pressures up to 30 MPa. The range of number-average molecular weights for these polymer cuts is from about 210 to 4960. The Tait equation represents accurately the effect of pressure on the liquid densities. Isothermal compressibilities for each polymer cut can be calculated with the aid of this equation. The experimental results reveal that the density of PEG increases with the average molecular weight but an opposite dependence is found for PPG. Nevertheless, the densities become insensitive to molecular size when the molecular weights of PEG are greater than 420 and those of PPG are greater than 3420. These new PVT data are correlated with both the Flory-Orwoll-Vrij and the Schotte equations of state. The characteristic parameters of the models so determined appear to depend on the molecular weight of polymers.
