ISO/TR 20659-2:2024

This document gives information on an interlaboratory comparison for the determination of the time-dependent structural change (thixotropy) using rheological test methods. Thixotropy is the reversible, time-dependent decrease of shear viscosity η at a constant shear rate γ or shear stress τ.
This document provides examples of fields of application, in which important material properties can be characterized by the thixotropy. These fields of application include:
—     effectiveness of rheological additives and thixotropic agents, respectively;
—     stability of the structure at rest (e.g. behaviour when starting to pump);
—     wet film thickness after processing;
—     levelling and sagging behaviour (e.g. without brushmarks or sag formation);
—     orientation of effect pigments.