Beaucoup de fluides naturels, en particulier les huiles lourdes, sont des mélanges complexes de molécules possédant une large distribution de tailles et de propriétés chimiques. Dans ces systèmes, la dynamique des molécules est complexe et le comportement de relaxation et de diffusion ne peut pas se décrire par un simple temps de relaxation ou coefficient de diffusion. Néanmoins, la relaxation RMN à bas champ et les mesures de diffusion sont devenus des outils puissants pour étudier de tels fluides. On peut contourner la complexité en analysant les mesures en termes de fonctions de distributions à une et deux dimensions. Les fonctions de distribution de relaxation et de diffusion à une dimension sont directement reliées à la composition des fluides. On montre également que l'analyse de la forme des déclins de relaxation et de diffusion permet de prédire la dépendance en température de la viscosité. Les fonctions de distribution à deux dimensions permettent de suivre d'autres aspects de la dynamique moléculaire. Les corrélations entre les comportements de relaxation et peuvent être utilisés pour détecter des mouvements lents et mettre en évidence l'agrégation des molécules en structures supramoléculaires. Les corrélations entre les fonctions de distribution de diffusion et de relaxation donnent enfin des informations sur la composition chimique des fluides étudiés.
Many natural fluids, including crude oils, are complex mixtures of molecules with a broad range of sizes and chemical properties. In such systems, the molecular dynamics is complex and the relaxation and diffusion behavior cannot be described by a single relaxation time or diffusion coefficient. Nevertheless, low field NMR relaxation and diffusion measurements have become powerful tools for the study of such fluids. The complexity can be overcome by analyzing the measurements in terms of one- and two-dimensional distribution functions. The one-dimensional relaxation and diffusion distribution functions are directly related to the composition of the fluids. We also show that from the analysis of the shape of the relaxation and diffusion decay, it is possible to predict the temperature dependence of viscosity. Two-dimensional distribution functions probe further aspects of the molecular dynamics. The correlation between and relaxation behavior can be used to detect the presence of slow motion and to probe the aggregation of molecules into supermolecular structures. Diffusion–relaxation distribution functions give information about the chemical composition of the fluid.
Mot clés : Fluides complexes, Huiles lourdes, Relaxation à bas champ, Diffusion, Transformée de Laplace Inverse, Composition de fluide, « Scaling »
Denise E. Freed 1 ; Martin D. Hürlimann 1
@article{CRPHYS_2010__11_2_181_0, author = {Denise E. Freed and Martin D. H\"urlimann}, title = {One- and two-dimensional spin correlation of complex fluids and the relation to fluid composition}, journal = {Comptes Rendus. Physique}, pages = {181--191}, publisher = {Elsevier}, volume = {11}, number = {2}, year = {2010}, doi = {10.1016/j.crhy.2010.06.016}, language = {en}, }
TY - JOUR AU - Denise E. Freed AU - Martin D. Hürlimann TI - One- and two-dimensional spin correlation of complex fluids and the relation to fluid composition JO - Comptes Rendus. Physique PY - 2010 SP - 181 EP - 191 VL - 11 IS - 2 PB - Elsevier DO - 10.1016/j.crhy.2010.06.016 LA - en ID - CRPHYS_2010__11_2_181_0 ER -
Denise E. Freed; Martin D. Hürlimann. One- and two-dimensional spin correlation of complex fluids and the relation to fluid composition. Comptes Rendus. Physique, Volume 11 (2010) no. 2, pp. 181-191. doi : 10.1016/j.crhy.2010.06.016. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2010.06.016/
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