Rheology of Dispersions

Normalized non-ergodicity parameter F (qd, t = ∞) for different separation parameter  to the glass transition with smooth crossover to the analytic qd = 0 value. Comparisson

Colloidal dispersions offer a wide range of technological applications ranging from cosmetics over food science to building materials. Sufficiently high concentrated dispersion can show a liquid to glass transition. Understanding the mechanical behavior of colloidal glasses is crucial for developing a fundamental theory as well as for processing and the applications of the final products.
Mechanical stress govern the flow and deformation dynamics in liquids and solids. To sudden deformation a liquid flows and a solid responses elastically. Recently [1] discovered, that colloidal dispersion show precursors of the emergence of rigidity, time-dependent long-ranged anisotropic stress correlations, close to the transition form liquid to glass. We intend to work this insight further by applying the microscopic theoretical framework of MCT (mode coupling theory) and we will put it to test with advanced rheological studies on model colloidal suspensions in collaboration with groups at the  Karlsruher Institut f ̈ur Technologie (KIT) (Prof. Dr. Manfred Wilhelm and Dr. Nico Dingenouts)

Frequency dependent storage and loss moduli G⊥,′ and G⊥,′′ in linear response from MCT calculation, corresponding to the macroscopic qd = 0 and microscopic qd = 7.2 stress reponse.
Frequency dependent storage and loss moduli G⊥,′ and G⊥,′′ in linear response from MCT calculation,
corresponding to the macroscopic qd = 0 and microscopic qd = 7.2 stress reponse.

References

[1] F. Vogel, A. Zippelius and M. Fuchs, Europhys. Lett., 125, 68003 (2019)

[2] M. Caraglio, L. Schrack, G. Jung & T. Franosch, Commun. Comput. Phys., 29 (2021), pp. 628-648 (2021)

[3] Bayer, M., J. M. Brader, F. Ebert, E. Lange, M. Fuchs, G. Maret, R. Schilling, M. Sperl and J. P. Wittmer,
Phys. Rev. E, 76, 011508 (2007)