Constitutive equations for Ca2+ -alginate gels

Constitutive equations accounting for the coupling between chemical and mechanical phenomena are developed for the Ca2+ alginate gel from the framework of thermodynamics of irreversible processes with internal variables. The development of the model is based on the Gibbs–Duhem relation and kinetic relations acting on generalized non-equilibrium forces. The constitutive equations are then compared to mechanical data obtained from uniaxial compressive tests at different velocities. A good agreement is observed between model and data. Furthermore, the model is able to predict the evolution of the mechanical response when the initial quantity of crosslinked Ca2+ ions varies.