(725g) Mechanical Properties of Ionically Crosslinked Alginate Gels

Polymer network and gels show nonlinear elastic responses under applied load. They may stiffen or soften under large deformation. The nonlinearity is related to the network structure, i.e. flexibility of chain and chain elongation ratio, crosslinking density, nature and length of crosslinking, and environmental conditions. Here, we investigate strain stiffening behavior of ionically cross-linked alginate hydrogel using large amplitude oscillatory shear (LAOS). The gels were obtained by using divalent calcium salt. Alginate volume fraction was kept constant (1 wt. %) and alginate to calcium ratio was varied to obtain gels with different crosslink density. The nonlinear rheological parameters are estimated from the stress responses to elucidate the strain stiffening behavior of the structure. The relationship between molecular structure and macroscopic elastic responses will be presented. Our results provide a better understanding on the deformation mechanism of ionic alginate gel under large deformation.