Multiple interval thixotropic test (miTT)—an advanced tool for the rheological characterization of emulsions and other colloidal systems

• Published in: Rheologica acta 2022-03, Vol.61 (3), p.229-242
• Main Authors: Stadler, Florian J., Cui, Shuming, Hashmi, Saud, Handschuh-Wang, Stephan, Li, Wenqiang, Wang, Shichang, Yan, Zhi-Chao, Zhu, Guangming
• Format: Article
• Language: English
• Subjects: Cellulose; Characterization and Evaluation of Materials; Chemistry and Materials Science; Complex Fluids and Microfluidics; Emulsions; Engineering; Food Science; Graphene; Laboratories; Materials Science; Mechanical Engineering; Mechanical tests; Original Contribution; Polymer blends; Polymer melts; Polymer Sciences; Rheological properties; Rheology; Shear rate; Soft and Granular Matter; Test procedures; Viscosity
• ISSN: 0035-4511; 1435-1528
• DOI: 10.1007/s00397-021-01323-y

In the last years, the 3iTT protocol—a dynamic-mechanical test (DMT) at low deformation and constant frequency, followed by a start-up flow (SUF) at constant shear-rate, and a DMT—was developed as an alternative to check for changes in material behavior, which was extended to form the multiple interval thixotropic test protocol (miTT), differing in modifying the shear rates systematically. The results of this test routine are a viscosity function η( γ ˙ ) with increasing and decreasing γ ˙ and the dependence of G’ and G” on γ ˙ previous test . More importantly, the G’ and G” are strongly influenced by the previously applied shear rate. While regular emulsions show a decrease of G’ and G” upon a higher shear rate γ ˙ in the previous shear step, the pickering emulsions with graphene oxide show an increase. In both cases, the change is approximately reversible. The changes in G’ and G” correlate well with the emulgel composition.