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Zero-shear viscosity η0 is one of the most important rheological parameters used in polymer industry. The value of η0 is determined at the end of the creep phase as

η0 = τ0 / γ ̇ 3 = τ0 / tanβ

Unit: [Pas]; with the constant shear rate γ ̇ 3 = Δγ3 / (t2 – t1) = (γ3 – γ2) / (t2 – t1) = tanβ which is independent of time (see Figure 6.8); γ ̇ 3 is often referred to as γ ̇ 0.

The value of zero-shear viscosity corresponds to the behavior of the dashpot D3 in the Burgers model, resulting in a “creep rate” value, i. e. in a very low rate of deformation or shear rate. In order to avoid exceeding the limit of the LVE deformation range between the time points t1 and t2, the total deformation value should not increase too much in this period (see also Chapter 6.2.1: values of γmax).