*2.6. Thixotropic Properties*

### 2.6.1. Constant Shear Rate

Shear stress or *η*50 values were used to determine the time-dependent behavior of gum solutions at 25 ◦C. The experimental data could be fitted to the Weltman model (Equation (2)) and second-order structural kinetic model (Equation (3)), with *n* =2[26,27].

$$
\sigma = a + b \ln t \tag{2}
$$

In Equation (2), *σ* is the shear stress at time *t* (Pa), *a* is the initial shear stress (Pa), *b* is the time coefficient of thixotropic breakdown (Pa), and *t* is the time of shearing (s).

$$
\left[\frac{\eta - \eta\_c}{\eta\_0 - \eta\_c}\right]^{(1-n)} = (n-1)kt + 1\tag{3}
$$

In Equation (3), *η*0 is the initial apparent viscosity at *t* = 0 (structured state), *ηe* is the equilibrium apparent viscosity as *t* → ∞ (non-structured state), *k* = *k*(*γ*) is the rate constant, and *n* is the order of the structure breakdown reaction assumed as 2 in the second-order structural kinetic model.
