PVT of fractionation cuts of poly(ethylene glycol) and poly(propylene glycol) from 298 K to 338 K and pressures up to 30 MPa

PVT data are measured for ten fractionation cuts of poly(ethylene glycol) ( PEG) and poly(propylene glycol) (PPG) at temperatures (298-338) K and press ures 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 accura tely the effect of pressure on the liquid densities. Isothermal compressibi lities for each polymer cut can be calculated with the aid of this equation . The experimental results reveal that the density of PEG increases with th e average molecular weight but an opposite dependence is found for PPG. Nev ertheless, the densities become insensitive to molecular size when the mole cular 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 an d the Schotte equations of state. The characteristic parameters of the mode ls so determined appear to depend on the molecular weight of polymers.