Simultaneous measurement of the concentration of a supercritical gas absorbed in a polymer and of the concomitant change in volume of the polymer. The coupled VW-pVT technique revisited

Results for CO2 in medium-density polyethylene, MDPE, and in poly(vinylidene fluoride), PVDF (or PVF2), in the range of temperatures up to 391 K and pressures up to 43 MPa, are reported and discussed. Experiments allow the apparent concentration of gas dissolved in the polymer to be established; the associated swelling of the polymer is estimated using the Sanchez-Lacombe equation of state. Then, the data of the corrected concentration of the gas in the polymer are correlated with the semi-empirical 'dual-mode' model. Whenever possible to compare our results are in good agreement with existing literature data.