Page 270 - Gas Adsorption Equilibria

256 Chapter 5

Eqs. (2.9, 2.10). They show a monotonous increase with increasing sorptive
gas density and coincide remarkably well thus proving – in this example –
that oscillometric and gravimetric measurements lead (within experimental
uncertainties) to identical results.

Figure 5.8. Reduced masses resulting from oscillometric and gravimetric adsorption
measurements of on activated carbon (Norit R1 Extra) at 293 K.
Gibbs excess masses and absolute masses adsorbed

3. OSZILLOMETRIC - GRAVIMETRIC
MEASUREMENTS OF GAS ABSORPTION IN
SWELLING MATERIALS

3.1 Introductory Remarks

Polymeric materials can absorb considerable amounts of gas, for example
especially at elevated pressures (p) and temperatures (T) above the so-
called glass transition temperature [5.19]. This often causes changes in size
and volume of the polymer, which have to be taken into account in industrial
processing situations, for example in gas separation processes using
polymeric sorbent materials [5.20]. Sorption phenomena of swelling polymers
cannot be measured adequately by either gravimetric or volumetric methods,