Poroelasticity of a covalently crosslinked alginate hydrogel under compression

This paper studies the poroelastic behavior of an alginate hydrogel by a combination of theory and experiment. The gel-covalently crosslinked, submerged in water, and fully swollen-is suddenly compressed between two parallel plates. The gap between the plates is held constant subsequently, and the force on the plate relaxes while water in the gel migrates. This experiment is analyzed by using the theory of linear poroelasticity. A comparison of the relaxation curve recorded in the experiment and that derived from the theory determines the elastic constants and the permeability of the gel. The material constants so determined agree well with those determined by using a recently developed indentation method. Furthermore, during relaxation, the concentration of water in the gel is inhomogeneous, resulting in tensile hoop stresses near the edge of the gel, and possibly causing the gel to fracture.