Compression-Permeability Properties of Compressed Bed of Superabsorbent Hydrogel Particles

The average pore size of the gel network of a superabsorbent hydrogel particle was evaluated based on the data of the permeation rate of water through the compressed bed of gels obtained with the use of a compression-permeability cell (C-P cell). The pore size evaluated based on the Happel's cell model using the C-P cell data was compared with that obtained from the Kozeny-Carman equation in which the Kozeny constant k was assumed to be 5.0. It was clarified that the use of k = 5.0 in Kozeny-Carman equation underestimated the pore size compared to the calculations using the Happel's cell model. Moreover, the effect of bound water in the gel was clarified.