ADSORPTION AND DESORPTION OF WATER-VAPOR ON AN ABSORBENT POLYACRYLIC POLYMER .3. ROLE OF LOCAL THERMAL EFFECT IN ADSORPTION-KINETICS

In this paper, water vapour adsorption kinetics on a superabsorbant polymer of the acyclic acid are studied. The shape of isokinetic curves plotted in the (p, T) equilibrium diagram, is the direct consequence of the adsorption exothermicity. This leads to modification of the local temperature and in consequence the vapour pressure reference at T(c) (temperature constraint), is different from the vapour pressure at T(r) (temperature response). There is no modification of the adsorption mechanism in relation to this thermal effect, as was observed in rehydration kinetics, or in Smith-Topley effect studies (evaporation, dehydration, decomposition of carbonates or ammonium salts).