Rheological and flow birefringence studies of rod-shaped pigment nanoparticle dispersions

We study rheological and rheo-optical properties of suspensions of anisometric pigment particles in a non-polar fluid. Different rheological regimes from the dilute regime to an orientationally arrested gel state were characterized and compared with existing theoretical models. We demonstrate the intricate flow behaviour in a wide range of volume fractions. A unique combination of the optical properties of the particles results in a giant rheo-optical effect: an unprecedentedly large shear stress-induced birefringence was found in the isotropic range, exhibiting a sharp pre-transitional behaviour

Comportement mécanique de films nanocomposites de nanofibrilles de cellulose et poly(oxyde d’éthylène)

National audienc

Multiscale shear rheology of cellulose nanofibril water suspensions

International audienc

Comportement mécanique de films de nanocomposites de nanofibrilles de cellulose et de PEO

National audienc

Influence de l'atmosphère sur l'oxydation initiale de l'acier ferritique AIS 441 lors du recuit final de recristallisation

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Evolution of the metal/oxide interface during the initial stages of the high temperature oxidation of ferritic stainless steels.

International audienc

Micro-mechanics of electrostatically stabilized suspensions of cellulose nanofibrils under steady state shear flow

International audienc

On the origins of the elasticity of cellulose nanofiber nanocomposites and nanopapers: a micromechanical approach

International audienc

A Possible Mechanism for Protrusions Formation at the Metal/Oxide Interface During Short Time Oxidation of Ferritic Stainless Steel

International audienceHigh temperature oxidation of ferritic stainless steel for short durations leads to the formation of an original morphology at the metal/oxide interface. This interface is composed of metallic protrusions localized in a chromium-rich oxide layer through a discontinuous silica film. In this paper we propose a mechanism based on preferential diffusion paths for the oxygen through the oxide that are governed by the distribution of the hydrostatic pressure in this layer. We point out that the mechanical contrast between the oxide and the metal subjected to creep can be critical for the hydrostatic pressure gradient magnitude inside the oxide layer. This observation is likely to promote the formation of protrusions for specific conditions of temperature and time of exposure to oxidation

Evolution of the metal-oxide interface during the initial stage of the high temperature oxidation of ferritic stainless steels.

International audienceTwo grades of ferritic stainless steel, a bi-stabilised Ti, Nb (AISI 441) and a stabilised Ti (AISI 439), were oxidised at 1060 degrees C under the simulated process atmosphere for durations between 45 and 1800 s. Focused ion beam coupled with field emission gun and scanning electron microscopy was carried out to investigate the cross-section morphology of the oxide growing on ferritic stainless steels. Matrix protrusions localised at the metal - chromia interface through the silica layer are observed and the following mechanism for their formation is proposed. During the first step of oxidation, interface undulation, induced by growth stresses, in combination with silica precipitation at the metal - oxide interface lead to the formation of matrix protrusions in the chromia layer. For an increased oxidation time, due to the laterally silica growth matrix protrusions are trapped into the Cr(2)O(3) layer as matrix inclusions