Overview
ABSTRACT
Viscoelastic measurement probes the dynamics of fluid (or liquid) materials by transferring a shear stress of varying frequency and amplitude via interfacial contact. However, this transfer chain is not optimized. By strengthening the interfacial interaction with the substrate, the shear stress response can be several decades higher, further revealing that the shear modulus of fluids does not collapse at the sub-millimeter scale but acquires a finite value.
Mesoscopic elasticity opens the way to another understanding of instabilities, slow relaxations, shear-induced transitions, and the identification of non-equilibrium properties, particularly concerning microfluidic or thermal transport, whose mechanisms prove to be very different from those observed at the macroscopic scale.
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Read the articleAUTHORS
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Hakima MENDIL-JAKANI : UPMC Engineer –, Ph.D. in Science - CEA Research Director, SyMMES, Grenoble, France
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Laurence NOIREZ : –, EAHP Engineer, Ph.D. - CNRS Research Director, Gif-sur-Yvette, France
INTRODUCTION
Viscoelastic analysis is an integral part of the methods used to characterize deformable materials, whether they are fluids, plastics, gels, foams, biological fluids, etc. It provides insight into how a material behaves in response to mechanical stress across a wide range of frequencies, from one-thousandth of a rad/s to about 100 rad/s. Shear stress allows us to distinguish between solid and liquid (viscous) behavior based on the latter’s lack of shear resistance.
Given the importance of the information derived from viscoelastic analysis, the objective will be to optimize the measurement so that it reflects the properties of the material under consideration as accurately as possible. The innovation consists of optimizing the shear stress transfer chain for measuring the dynamic properties of fluids within a given frequency range, typically from 0.01 Hz to 15 Hz.
This transfer chain is notably improved by enhancing the interfacial interactions between the fluid and the substrate using surfaces with high wettability toward the fluid, whereas conventional measurements do not account for this parameter. Such an innovative integration highlights the need to consider the fluid’s properties as scale-dependent. At the submillimeter scale, fluids may exhibit shear elasticity, the effects of which remain difficult to detect using conventional approaches at the millimeter scale. It is therefore necessary to revisit the measurement protocols used in rheology, drawing on advances made in related disciplines such as tribology, adhesion, wetting, and thermal analysis.
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KEYWORDS
fluids | liquids | shear elasticity | sub-millimeter scale | viscoelastic properties | mesoscopic elasticity
EDITIONS
Other editions of this article are available:
- Archived version Jan 2010 1 by Patrick BARONI, Hakima MENDIL-JAKANI, Laurence NOIREZ
CAN BE ALSO FOUND IN:
Innovations for the full measurement of the viscoelastic properties of fluids
Principles of Measuring Viscoelastic Properties
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