Multiple light scattering in random systems: Analysis of the backscattering spot image

This study concerns the multiple scattering of light in random granular systems and the analysis of the image formed by the light scattered by a random medium. We developed an imagery method with high grey level resolution for visualization and analysis of the intensity profile in the backscattering spot image. We further present statistical models for the radiative transfer in granular media only involving the photon mean path length, the asymmetry factor and the absorption probability of photons. A renormalization of the photon trajectory in the medium gives a photon transport equation for anisotropic scattering and leads to an analytical expression for the intensity profile in the backscattering spot. We finally compare the results from imagery experiments with the predictions from numerical simulations and statistical models

Experimental and analytical study of periodic heat conduction in a multilayer medium

We have performed experiments consisting to probe a multilayer material with a pulsed laser light flux and to measure the time dependent temperature at interfaces. A real time and high gray level imagery technique gives the backscattered flux at the entrance face of the composite and the incident heat flux entering in the slab. We further present an analytical model for studying transient diffusive phenomena in a one dimensional multilayer medium submitted to periodic external conditions. This approach uses a matricial formalism and the development of the incident thermal flux on an orthogonal complete base of rectangular functions called "Walsh functions". The use of the transfer matrix formulation then leads to a eigenvalues transcendental equation. The experimental method for steady or periodic heating of the slab together with the model predictions yields the thermo-physical parameters of the multilayer medium

Evaluation of the mechanical properties of compacted paraffin powders. Effect of formulation

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Thermoplastic starch plasticized by an ionic liquid

International audienceThermoplastic starch (TPS) plasticized by 1-butyl-3-methylimidazolium chloride ([BMIM]CI) was obtained by melt processing. The resulting electrically conductive TPS samples were less hygroscopic than glycerol plasticized TPS samples. Despite this lower water uptake, [BMIM]CI seems to be intrinsically a more efficient plasticizer of starch. [BMIM]CI plasticized TPS samples show a much higher elongation at break in the rubbery state than the glycerol plasticized TPS samples. Their unusually low rubbery Young's modulus for thermoplastic starch (0.5 MPa) suggests a strong reduction of hydrogen bonds between the starch chains due to the presence of the ionic liquid. A detailed IR spectroscopy analysis supports this interpretation

Plasticization of starch by a ionic liquid: melt processing and mechanical properties

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