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 simultane ously 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 s ize 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 i ts gravity. This leads to an additional information on the volume of the sa mple. The dynamic measurements can be performed either by slow oscillations of a rotational pendulum or by the relaxational motion of a floating rotat or. Sample data of the mass absorbed (m) and volume (V) of the loaded sorbe nt are given for the system carbon dioxide/polycarbonate pellets at T = 293 K in the pressure range 0 < p < 6 MPa.