Combined use of NMR relaxation times and self-diffusion coefficients for characterizing solvent bound to cetyltrimethylammonium bromide micelles in water and formamide

Abstract In order to characterise the structure and flow behaviour of model chocolate systems Nuclear Magnetic Resonance (NMR) and rheometry were used to determine the T1 - and T2 - NMR relaxation times and their corresponding flow functions. T1 and T2 characterise the molecular mobility of fluids and correlate with both the zero-shear-rate and infinity viscosity of various chocolate model systems (determined with rotational rheometry and capillary rheometry). Based on this correlation, NMR provides the possibility to determine characteristic viscosities of chocolate masses by means of NMR-relaxation experiments. The viscosities of chocolate masses are important process parameters, as they are used for quality control of the production process. An online process viscosimetry via T2 relaxation would allow the installation of an efficient process control and, thus, a process automation. This NMR application with comparatively short measuring times is especially interesting for disperse systems where the use of conventional rheometric techniques may cause large errors. The only prerequisite for the measurement of the viscosities using NMR is a previous calibration. This was performed with the help of rotational and capillary rheometry. The NMR self-diffusion experiments are especially appropriate to characterise the influence of emulsifiers on the structure and the flow behaviour of chocolate masses.

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Temperature and Pressure Dependence of the Diffusion Coefficients and NMR Relaxation Times of Mixtures of Alkanes

The Journal of Physical Chemistry B ◽

10.1021/jp810145m ◽

2009 ◽

Vol 113 (13) ◽

pp. 4293-4302 ◽

Cited By ~ 13

Author(s):

Denise E. Freed

Keyword(s):

Pressure Dependence ◽

Diffusion Coefficients ◽

Relaxation Times ◽

Nmr Relaxation ◽

Nmr Relaxation Times ◽

Temperature And Pressure

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Modification of Transverse NMR Relaxation Times and Water Diffusion Coefficients of Kiwifruit Pericarp Tissue Subjected to Osmotic Dehydration

Food and Bioprocess Technology ◽

10.1007/s11947-012-0818-5 ◽

2012 ◽

Vol 6 (6) ◽

pp. 1434-1443 ◽

Cited By ~ 36

Author(s):

Patricio Santagapita ◽

Luca Laghi ◽

Valentina Panarese ◽

Urszula Tylewicz ◽

Pietro Rocculi ◽

...

Keyword(s):

Diffusion Coefficients ◽

Osmotic Dehydration ◽

Relaxation Times ◽

Nmr Relaxation ◽

Water Diffusion ◽

Nmr Relaxation Times

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Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

Molecules ◽

10.3390/molecules26175218 ◽

2021 ◽

Vol 26 (17) ◽

pp. 5218

Author(s):

Kevin Lindt ◽

Bulat Gizatullin ◽

Carlos Mattea ◽

Siegfried Stapf

Keyword(s):

Diffusion Coefficients ◽

Relaxation Times ◽

Chemical Species ◽

Nmr Relaxation ◽

Molecular Size ◽

Relaxation Rates ◽

Vast Number ◽

Self Diffusion ◽

Slowing Down ◽

The Individual

The distribution of NMR relaxation times and diffusion coefficients in crude oils results from the vast number of different chemical species. In addition, the presence of asphaltenes provides different relaxation environments for the maltenes, generated by steric hindrance in the asphaltene aggregates and possibly by the spatial distribution of radicals. Since the dynamics of the maltenes is further modified by the interactions between maltenes and asphaltenes, these interactions—either through steric hindrances or promoted by aromatic-aromatic interactions—are of particular interest. Here, we aim at investigating the interaction between individual protonic and deuterated maltene species of different molecular size and aromaticity and the asphaltene macroaggregates by comparing the maltenes’ NMR relaxation (T1 and T2) and translational diffusion (D) properties in the absence and presence of the asphaltene in model solutions. The ratio of the average transverse and longitudinal relaxation rates, describing the non-exponential relaxation of the maltenes in the presence of the asphaltene, and its variation with respect to the asphaltene-free solutions are discussed. The relaxation experiments reveal an apparent slowing down of the maltenes’ dynamics in the presence of asphaltenes, which differs between the individual maltenes. While for single-chained alkylbenzenes, a plateau of the relaxation rate ratio was found for long aliphatic chains, no impact of the maltenes’ aromaticity on the maltene–asphaltene interaction was unambiguously found. In contrast, the reduced diffusion coefficients of the maltenes in presence of the asphaltenes differ little and are attributed to the overall increased viscosity.

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