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Université de Fribourg

Variations of the Herschel–Bulkley exponent reflecting contributions of the viscous continuous phase to the shear rate-dependent stress of soft glassy materials

Caggioni, Marco ; Trappe, Veronique ; Spicer, Patrick T.

In: Journal of Rheology, 2020, vol. 64, no. 2, p. 413–422

We explore the flow behavior of concentrated emulsions for which the viscosity of the continuous phase can be significantly varied by changing the temperature. The exponents obtained by fitting the shear rate-dependent stress with the popular Herschel–Bulkley (HB) model display a systematic dependence on the viscosity of the continuous phase, revealing that viscous dissipation via the...

Université de Fribourg

The structural colors of photonic glasses

Schertel, Lukas ; Siedentop, Lukas ; Meijer, Janne-Mieke ; Keim, Peter ; Aegerter, Christof M. ; Aubry, Geoffroy J. ; Maret, Georg

In: Advanced Optical Materials, 2019, p. 1900442

The color of materials usually originates from a combination of wavelength‐dependent absorption and scattering. Controlling the color without the use of absorbing dyes is of practical interest, not only because of undesired bleaching properties of dyes but also regarding minimization of environmental and health issues. Color control without dyes can be achieved by tuning the material's...

Université de Fribourg

Observation of strongly heterogeneous dynamics at the depinning transition in a colloidal glass

Şenbil, Nesrin ; Gruber, Markus ; Zhang, Chi ; Fuchs, Matthias ; Scheffold, Frank

In: Physical Review Letters, 2019, vol. 122, no. 10, p. 108002

We study experimentally the origin of heterogeneous dynamics in strongly driven glass-forming systems. Thereto, we apply a well-defined force with a laser line trap on individual colloidal polystyrene probe particles seeded in an emulsion glass composed of droplets of the same size. Fluid and glass states can be probed. We monitor the trajectories of the probe and measure displacements and...