D. Gourgouillon et al., SIMULTANEOUS VISCOSITY AND DENSITY-MEASUREMENT OF SUPERCRITICAL CO2-SATURATED PEG-400, The Journal of supercritical fluids, 13(1-3), 1998, pp. 177-185
In order to analyse the effect of supercritical fluid (SCF) addition o
n polymer viscosity we have used, for the first time, a high precision
vibrating wire instrument, for the simultaneous measurement of viscos
ities and densities of a SCF-saturated polymer. For the density measur
ements, this technique makes use of the buoyancy force exerted by a fl
uid on a solid sinker, detected by means of a vibrating wire sensor pl
aced inside the measuring cell. The viscosity and density of the fluid
are obtained by analysis of the resonance curve of the vibrating-wire
, using a rigorous model for describing the hydrodynamic effects of th
e fluid on the wire motion. Results of the preliminary measurements ca
rried out on a commercial linear thermoplastic oligomer [Poly (ethylen
eglycol) 400] saturated with CO2 are presented, in a range of temperat
ures from 313 to 348 K (3 isotherms) and at pressures up to 25 MPa. A
sharp decrease of the viscosity was observed for all temperatures. The
highest viscosity reduction was reached at the lowest temperature. (C
) 1998 Elsevier Science B.V.