抄録
Superabsorbent hydrogels display a drastic change in volume by absorbing several hundred times their own weight of water, and they have attracted a considerable amount of attention in recent years in widely diversified fields. It is well-known that the dynamic behaviors of hydrogel particles swelling in the solution are markedly influenced by the ionic environment of the solution. In this study, both expression and expansion properties of the granular bed of the superabsorbent hydrogels under the action of the mechanical loads were investigated at various ionic environments using the KCl solution, in order to clarify the role of the osmotic pressure of the solution on the deformation behaviors of hydrogel particles. The expression behaviors were described accurately via the simplified computation method based upon the modified Terzaghi model. As the concentration of the KCl solution was increased, the expression rate was increased, and the packed hydrogels became dense. Interestingly, these results were similar to the tendency obtained under the absence of the mechanical loads. It was revealed that the data were analyzed well on the basis of the idea of the effective osmotic pressure of the solution. Moreover, in the expansion process of the compressed bed of hydrogel particles, it was clarified that the secondary expansion effect known as the creep effect plays an important role on the expansion behavior. The dynamic behaviors of the gel expansion were evaluated well by the simplified computation method in which the creep effect was taken into account.
