Modeling the rheology of gelatin gels for finite deformations. Part 2. Viscoelastic solid model

The viscoelastic solid model proposed in this work can predict the rheological responses of gelatin gels for finite deformations. This rheological model considers a degree of physical cross-links at a given maturation time, which is partially attained from those links totally available when a pure elastic network is achieved. Thus, both an elastic network formed by permanent links on the average and a viscoelastic network composed of the remaining adaptive links are described at each maturation time. This model for gelatin gels considers appropriately the interplay between the networks involving: (a) viscoelastic relaxation as a consequence of an imposed mechanical history, (b) average degree of physical cross-links in the partially generated permanent network acting in the short-term mechanical response. In this context of analysis the standard viscoelastic solid is obtained asymptotically for small deformations. Also the effect of shear rate on the shear test is studied and the braking phenomenon is analysed in relation to the formation of microstructure by considering viscoelastic parameters.