Fig. 2.

Rheological response of a solid-like network that is embedded in a liquid. (A) Phenomenological model for the quantitative evaluation of rotation traces, from which three parameters are deduced: the shear modulus G of the solid network, the viscosity η₀ of the embedding liquid, and the effective viscosity η₁ representing plastic deformation of the solid network. The constant shear stress σ is suddenly applied at time 0. The expression of the characteristic time τ is given in the text, and the strain amplitude Δγ is the prefactor of the exponential term in Eq. 1. (B) Examples of strain traces acquired during the aging and hardening of glycerol, induced by the application of a constant shear stress σ = 107 Pa at time t = 0. The plot shows data taken during the first 4 days of an observation period of 2 weeks. The traces were fitted with Eq. 1 resulting from the model described in A, except when breaking events occurred (e.g., day 1, p.m.). The dashed lines give two examples of these fits to the data.