Measurement of gas absorption in a swelling polymeric material by a combined gravimetric-dynamic method

A new gravimetric-dynamic method is described allowing to measure simultaneously the amount of gas absorbed by a polymeric material and its change in volume due to absorption. The method determines a 3-dimensional change in size of the polymer sample. The sample can be of either dense, pulverous, or pellet-like shape. The method combines well known gravimetric measurements with a dynamic method where the inertia of mass is determined instead of its gravity. This leads to an additional information on the volume of the sample. The dynamic measurements can be performed either by slow oscillations of a rotational pendulum or by the relaxational motion of a floating rotator. Sample data of the mass absorbed (m) and volume (V) of the loaded sorbent are given for the system carbon dioxide/polycarbonate pellets at T = 293 K in the pressure range 0 < p < 6 MPa.