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Pré-Publication, Document De Travail Année : 2020

Mechanics and structure of carbon black gels under high-power ultrasound

Résumé

Colloidal gels made of carbon black particles are "rheo-acoustic" materials: their mechanical and structural properties can be tuned using high-power ultrasound, sound waves with submicron amplitude and frequency larger than 20 kHz. The effect is demonstrated using two experiments: rheology coupled to ultrasound to test for the gel mechanical response and an ultra small-angle X-ray scattering experiment coupled to ultrasound to test for structural changes within the gel. We show that high-power ultrasound above a critical amplitude softens carbon black gels at rest due to the formation of micro-cracks in the bulk. The gel softens exponentially with a characteristic time of a few seconds. High-power ultrasound also eases the flow of the gel thanks again to the formation of micro-cracks. High shear rates however tend to select a gel structure that is less sensitive to ultrasound.
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Dates et versions

hal-03049332 , version 1 (29-11-2021)

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Noémie Dagès, Pierre Lidon, Guillaume Jung, Frédéric Pignon, Sébastien Manneville, et al.. Mechanics and structure of carbon black gels under high-power ultrasound. 2020. ⟨hal-03049332⟩
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