Preliminary analysis of Diffusion Coefficient Measurements in ternary mIXtures 4 (DCMIX4) experiment on board the International Space Station

Mialdun, Aliaksndr; Bataller, Henri; Bou-Ali, M. Mounir; Braibanti, Marco; Croccolo, Fabrizio; Errarte, Ane; Ezquerro, J.M.; Fernández, J.; Gaponenko, Yuri; García-Fernández, L.; Rodríguez, José Luis García; Shevtsova, Valentina

doi:10.1140/epje/i2019-11851-6

Cited by 16 publications

(8 citation statements)

References 32 publications

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“…Thermodiffusion experiments in ternary mixtures are performed on ground, by using different optical techniques [10,14,17,18], or in microgravity in order to avoid both convection and sedimentation. The thermodynamic characterization of ternary mixtures is one of the objectives of the following ESA projects: Diffusion Coefficient Measurements in ternary mIXtures (DCMIX) [18][19][20][21][22][23], Soret Coefficients in Crude Oil (SCCO) [1,[24][25][26][27] and Giant Fluctuations [28], as further elaborated in a recent colloquium paper [29].…”

Section: Introductionmentioning

confidence: 99%

Coupled non-equilibrium fluctuations in a polymeric ternary mixture

et al. 2019

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We investigate by dynamic shadowgraphy the non-equilibrium fluctuations at the steady state of a thermodiffusion experiment in a polymeric ternary mixture of polystyrene-toluene-nhexane. The structure function of the refractive index reveals the existence of quite different decay times, thus requiring the analysis of a wide range of correlation times. This is related to the simultaneous presence of three distinct decay modes corresponding to (from fastest to slowest) relaxation of temperature fluctuations, of the concentration fluctuations of the mixed solvent, and of the concentration fluctuations of the polymer in the binary solvent. An investigation of the decay times at the corresponding diffusive regimes provides a measurement of the thermal diffusivity and the two eigenvalues of the mass diffusion matrix of the ternary mixture. Similar experiments were performed in the past but here, to suppress the confinement effect and obtain a more direct comparison with the theory, a thicker sample is studied. Moreover, also a faster camera is used allowing the experimental observation of faster modes, like the propagative ones. The experimental values of the decay times are eventually compared with those predicted by different available theories. Finally, we present a more complete theoretical model to describe the non-equilibrium fluctuations in the bulk of a ternary mixture at the steady state of a thermodiffusion experiment.

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Section: Introductionmentioning

confidence: 99%

Coupled non-equilibrium fluctuations in a polymeric ternary mixture

et al. 2019

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“…Under microgravity conditions the Soret effect can be used to generate a concentration gradient in a fluid mixture under controlled conditions by applying a temperature gradient to the layer of mixture, with the advantage that experiments can be iterated at will by imposing/removing the thermal gradient. This method has been exploited during several experiment s of t he European Space Agency on thermodiffusion under microgravity conditions (Braibanti et al 2019), which benefited from the fact that the absence of gravity allows to investigate purely thermodiffusive processes, in the absence of convective instabilities.…”

Section: Thermodiffusionmentioning

confidence: 99%

“…The results obtained with GRADFLEX allowed to establish that linearized hydrodynamics is suitable to provide a fully quantitative description of the static structure factor of non-equilibrium fluctuations under the ideal conditions where the amplitude of fluctuations is small, and the diffusive process is stationary. At the same time, the development of the DCMIX project of the European Space Agency showed the interest of a wide community of scientists in the investigation of mass transport processes in multi-component liquid mixtures (Bou-Ali et al 2015;Galand et al 2019;Shevtsova et al 2014;Triller et al 2018;Mialdun et al 2019). Multi component mixtures exhibit a rich stability diagram, where the stability of the sample in the presence of gravity is compromised by the presence of double diffusion processes, which can lead to convective instabilities even when the initial density profile of the sample is stable (Šeta et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Giant Fluctuations Induced by Thermal Diffusion in Complex Liquids

Vailati

Philipp

Bataller

et al. 2020

Microgravity Sci. Technol.

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The GRADFLEX experiment of ESA has shown that under microgravity conditions a stationary thermodiffusion process is accompanied by giant non-equilibrium fluctuations with size as large as the size of the sample. In the presence of small concentration gradients, the features of the non-equilibrium fluctuations can be described by means of linearized hydrodynamics. However, the linear models are not suitable to describe most cases of applicative interest, such as fluctuations induced by large gradients and under non-stationary conditions. Moreover, presently the investigation of non-equilibrium fluctuations has mainly involved single component fluids and binary mixtures, but recently transport processes in ternary mixtures have attracted increasing interest due to the experiments performed on the International Space Station in the framework of the DCMIX project of ESA. The Giant Fluctuations (NEUF-DIX) project of ESA will investigate non-equilibrium fluctuations during diffusive processes occurring in complex multi-component mixtures, where one of the components is a macromolecule, such as a polymer, a colloid or a protein. Important objectives will be the exploration of the features of the fluctuations under non-ideal conditions, such as large gradients, transient processes, and concentrated samples, and the understanding of how the fluctuations affect the interactions between macromolecules. The project involves the development of a dedicated facility, consisting of an array of shadowgraph optical instruments working in parallel, each one equipped with a thermal gradient cell. Here we outline the design concept of the facility and the results of performance tests performed on a breadboard to evaluate the suitability of the designed instrument to carry out scientific measurements of non-equilibrium concentration fluctuations in space.

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“…13,[17][18][19] The DCMIX3 system is composed of water, ethanol, and triethylene glycol, 20 and the last campaign, DCMIX4, includes three additional mixtures of the system toluene, methanol, and cyclohexane; one mixture containing fullerene and a polymer diluted in a binary solvent. 21 The processing of the ISS data revealed that the final results were sensitive to the applied methodology. This is especially interesting in systems close to the stability boundary.…”

Section: Introductionmentioning

confidence: 99%