Notice bibliographique
Résumé
<p>Shear banding, where a fluid spatially partitions into strain rate or shear bands in steadystate simple shear flow conditions, was first observed in wormlike micelles solutions and has since been observed in many other complex fluids. These solutions have been used extensively to explore the relationship between shear (or stress) banding and microstructure in complex fluids. This relationship is difficult to study because of its dynamic nature and there is still no clear consensus as to how banding relates to microstructural changes in wormlike micelles solutions. In this thesis, the rheology of a number of wormlike micelles solutions is examined using both conventional and novel techniques with the view to developing a better understanding of this relationship. The rheology of three wormlike micelles solutions composed of a surfactant cetylpyridinium chloride (CPCl) and counterion sodium salicylate in water with or without the salt sodium chloride were examined using mechanical rheometry and the rheo-optical techniques: homodyne photo-correlation spectroscopy (PCS), diffusing wave spectroscopy (DWS) and ellipsometry. Rheo-mechanical measurements were largely consistent with the predictions of the reptation-reaction model. While signi cant stress fluctuations were noted in one particular flow geometry, they were generally not observed in most rheomechanical measurements presented here, indicating that these fluctuations are not universal and that they are geometry dependent. Shear induced turbidity was directly observed in the cone-plate and parallel-plate geometries with turbid rings forming in samples that showed a stress plateau. The Poisson-renewal model, which extends the reptationreaction model to include the influence of high frequency modes on the linear rheology, was tested experimentally using mechanical rheometry, DWS microrheology and literature data. In most cases the data fitted the model behaviour quite well, giving a physically reasonable estimate of the average length of the micelles. DWS's spatial sensitivity to shear induced relative motion was then used to probe the flow behaviour of selected wormlike micelles solutions in the cylindrical-Couette, cone-plate and parallel-plate geometries. In the cylindrical-Couette, the 'flow-DWS' measurements were largely consistent with rheo-mechanical measurements and indicated that some wormlike micelles solutions were partitioning into apparently stable high and low strain rate bands in the vicinity of the stress plateau. While measurements in the cone-plate and parallel-plate geometries also suggested shear banding in samples that showed a stress plateau, the interpretation was less clear-cut. Homodyne PCS was combined with ellipsometry to examine the spatial relationship between strain rate and birefringence banding in selected wormlike micelles solutions in a cylindrical-Couette geometry. In contrast to the observations of previous workers, it was found here that the birefringence and strain rate bands did coincide. Furthermore, the high strain rate band was observed to be more turbid than the lower strain rate band suggesting a connection between strain rate, optical anisotropy and turbidity.</p>
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».