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This study concerns about one hundred kaolinite samples. Some of them were collected in « Bassin des Charentes », the others are commercial products from different countries. Correlation were pointed out between on one hand cristallochemical, superficial and rheological properties and on the other hand technological capacities of kaolinites as coating pigment for paper and card-board. Kaolins from Charentes present good characteristics regarding coating, except their low receptivity to ink resulting from the amount of particles sized lower than .1 µm. Successfull tests have been pursued to overcome this difficulty., Cette étude porte sur une centaine d'échantillons de kaolins provenant du Bassin des Charentes ou produits commerciaux étrangers. Elle met en évidence les corrélations existant entre les caractéristiques cristallochimiques superficielles et rhéologiques des kaolins et leurs performances dans le domaine du couchage des papiers et cartons. Les kaolins des Charentes possèdent les principales caractéristiques recherchées pour le couchage, hormis une réceptivité aux encres insuffisante, due à la présence de particules hyperfines (, Delon Jean-François, Liétard Olivier, Cases Jean-Maurice, Richard Michel, Sauret Georges, Maume Jean-Pierre. Possibilités d'emploi des kaolins des Charentes dans le couchage des papiers et cartons. In: Bulletin de Minéralogie, volume 105, 5, 1982. Cristallochimie des argiles kaoliniques et applications.

Human bronchial secretions were examined for chemical components and rheological properties. Proline-rich polypeptides (PRP) obtained by ultrasonic treatment and by contact with a cationic resin (AG 50WX2) were purified by gel-filtration chromatography and high-voltage electrophoresis. The chemical composition of these components allowed a classification according to their proline, glycine, glutamic acid and lysine contents. Rheological experiments suggest a biological role for the PRP in the fibrillar structure of sputum.

The crude oil is a non-Newtonian fluid exhibiting, during its flow, phenomena which cannot be described with the traditional models which consider the fluid as homogeneous. Thus, it is necessary to use or develop a more realistic approach which can take into account the microstructure characteristics of crude oils in the law of behaviour. The application of a non-linear differential model in the case of crude oil flow can not be used. This paper deals with the modelling approach resulting from rheology of the polymer solutions. The Modified Phan-Thien and Tanner model (MPTT) is considered in this paper for an axisymmetric flow in a pipe. The shear stresses calculation with this model is an important step as it allows to study subsequently some important phenomena as the corrosion or the pressure drop which is controlled by the friction factor under turbulent flow conditions. The calculations were about different crude oils and the obtained results are compared to experiments. Some discussions are given.

Concentrated suspensions are fluids which display complex rheological properties. These properties are modelled through structural equations which consider both the liquid and solid phases, but with a lack of consistency for the granular parameters (in particular the maximum packing fraction of non-model suspensions). The overall objective of this paper is to investigate the dependence of the viscosity of energetic concentrated suspensions on the physicochemical properties of their components. The properties with the most significant impact on the viscosity are chosen using the Design of Experiments methodology. The resulting model accounts for the mass median diameter D50 in small and large particles, the large particles density d, the specific surface area of small particles, the shear stress γ ̇ applied to the suspension, the viscosity of the suspending fluid η_f and a constant value for the volume fraction in solid ϕ≃0.51. Moreover, this model allows predicting the viscosity of the studied suspensions for a volume fraction in solid from 0 to 0.51 %, Les suspensions concentrées sont des fluides qui présentent des propriétés rhéologiques complexes. Ces propriétés sont modélisées par des équations structurelles qui considèrent à la fois les phases liquide et solide, mais avec un manque de lien avec les paramètres granulaires (en particulier la compacité des suspensions non modèles). L'objectif global de ce travail est d'étudier la dépendance de la viscosité de suspensions concentrées énergétiques aux propriétés physico-chimiques de leurs composants. Les propriétés ayant l'impact le plus significatif sur la viscosité sont choisies en utilisant la méthodologie des plans d’expériences. Le modèle résultant représente le diamètre médian D50 en volume de petites et grandes particules, la densité des grosses particules d, la surface spécifique des particules, la contrainte de cisaillement γ ̇ appliquée à la suspension, la viscosité du fluide de suspension ηf et une constante valeur pour la fraction volumique en solide φ≃0.51. De plus, ce modèle permet de prédire la viscosité des suspensions étudiées pour une fraction volumique en solide allant de 0 à 0,51 %.

Concentrated suspensions are fluids which display complex rheological properties. These properties are modelled through structural equations which consider both the liquid and solid phases, but with a lack of consistency for the granular parameters (in particular the maximum packing fraction of non-model suspensions). The overall objective of this paper is to investigate the dependence of the viscosity of energetic concentrated suspensions on the physicochemical properties of their components. The properties with the most significant impact on the viscosity are chosen using the Design of Experiments methodology. The resulting model accounts for the mass median diameter D50 in small and large particles, the large particles density d, the specific surface area of small particles, the shear stress γ ̇ applied to the suspension, the viscosity of the suspending fluid η_f and a constant value for the volume fraction in solid ϕ≃0.51. Moreover, this model allows predicting the viscosity of the studied suspensions for a volume fraction in solid from 0 to 0.51 %; Les suspensions concentrées sont des fluides qui présentent des propriétés rhéologiques complexes. Ces propriétés sont modélisées par des équations structurelles qui considèrent à la fois les phases liquide et solide, mais avec un manque de lien avec les paramètres granulaires (en particulier la compacité des suspensions non modèles). L'objectif global de ce travail est d'étudier la dépendance de la viscosité de suspensions concentrées énergétiques aux propriétés physico-chimiques de leurs composants. Les propriétés ayant l'impact le plus significatif sur la viscosité sont choisies en utilisant la méthodologie des plans d’expériences. Le modèle résultant représente le diamètre médian D50 en volume de petites et grandes particules, la densité des grosses particules d, la surface spécifique des particules, la contrainte de cisaillement γ ̇ appliquée à la suspension, la viscosité du fluide de suspension ηf et une constante valeur pour la fraction volumique en solide φ≃0.51. De plus, ce modèle permet de prédire la viscosité des suspensions étudiées pour une fraction volumique en solide allant de 0 à 0,51 %.

International audience; Dans la première partie de ce travail, on se propose de comparer le comportement rhéologique de bétons identifié à l'aide de différents rhéomètres, en utilisant une méthode de traitement des données permettant le tracé direct de la courbe d'écoulement du matériau. Dans une deuxième partie, les propriétés rhéologiques de bétons industriels sont étudiées au moyen d'un rhéomètre de forte capacité de couple muni d'une géométrie à ailettes. Les résultats permettent d'évaluer et de comparer les propriétés d'écoulement des bétons et de juger de la reproductibilité du procédé de fabrication. In the first section of this paper, the rheological behaviour of concretes obtained with different rheometers is investigated from a procedure allowing the plot of the flow curve of sheared material. Secondly, the rheological properties of industrial concretes are studied with a high torque vane rheometer. The flow properties of concrete are evaluated and compared, as well as the reproductibility of the making process of concrete.

After a short background history on solid third bodies, this paper proposes a tribological approach for understanding how a contact takes place when first bodies are in relative movement and are separated by a solid third body. This approach, based on rheology and third body flows, enables friction and wear in contacts “lubricated” by a solid third body to be identified and progressively modelled. Flows and rheology are the two notions used for analysing and structuring dynamic phenomena created by contacts and their interaction with the environment, in the physico-chemical and mechanical sense, i.e. with the ambient atmosphere and the mechanism concerned with the contact, respectively. Due to in-situ instrumentation difficulties, flows are evaluated in relation to those visualised in real time through one transparent first body. Rheology is also evaluated relatively, but by distinguishing the cohesion and ductility of the elements making up the third body that moves in the contact, over a given observation scale. As an illustration, this presentation relies on the behaviour of a contact containing a third body formed in-situ from a coating of MoS 1.6 .

The paper considers the behavior of third bodies in dry contacts. A description of the mechanism operating in contacts is given and the influence of external parameters outlined. Both physicochemical and mechanical conditions greatly influence third body behavior. Depending on third-body composition, the external influence can be more or less dramatic. Due to difficulties with experimentation, numerical modeling is suggested as a complementary tool. Two approaches for such modeling are described, the continuum and the discrete approach. At present these models are at an early development stage (two-dimensional simulations), and great efforts should be made for their further development. While an experimental apparatus can study phenomena at only one scale; namely the nanometer with AFM, or the micron to millimeter with fretting machines, modeling is able to range from the microscopic properties (particle interactions like coefficient of restitution) to the macroscopic properties by integration or averaging (load capacity, friction coefficient).

This paper reexamines the law of Starling on the exchanges of liquids through the capillaries at the light of the most recent data available in the literature.

Red blood cell Agglutinates can be dissociated by providing enough energy which may be supplied by shear stress in a viscometer. In this paper a new technique is proposed to determine dissociation parameters of erythrocyte immunological agglutinates by using a laser backscattering method. Backscattered light intensity increases during the process of agglutinate dissociation when a controlled shear stress in a transparent Couette viscometer is applied. The obtained curves of dissociation can be fitted by an exponential function. A numerical integration of the dissociation curves allows us to obtain a parameter associated to the energy used in the dissociation process. A satisfactory differentiation of erythrocyte sub-groups Al, Az, A,B and Am has been carried out using this technique.

The aim of this paper is to study the rheological properties of blood in patients with venous insufficiency.Measurements have been performed for 20 healthy control subjects and 20 patients presenting a venous insufficiency with varicose veins of lower limbs. Blood has been withdrawn from the veins of the lower limbs at rest and after 10 minutes of venous stasis (standing position and 100 mmHg tourniquet). The following measurements have been performed: hematocrit by microcentrifugation; fibrinogen by nephelometry; plasma viscosity by means of capillary viscosimeter (Myrenne KSPV4); deformability by Hanss hemorheometer using nucleopore membranes and red blood cell aggregation and disaggregation by means of a SEFAM erythro-aggregometer.1. Hematocrit was not significantly different between both groups of subjects at rest. However, it increased significantly after venous stasis in patients with varicose veins but it was not found to be increased in healthy subjects. 2. Before and after stasis, the fibrinogen level was higher in patients than in controls. After stasis, a significant increased was found only in the patient group. 3. Plasma viscosity was found to be modified as the same manner as the fibrinogen level. Besides, the fibrinogen level and plasma viscosity were found to be correlated to each other. 4. Before and after stasis, red cells of patients were significantly less deformable than those of controls. After stasis, they were found to be more altered, in patients. But there were no difference in controls before and after stasis. 5. Aggregation and disaggregation parameters have been found to be disturbed in patient group. Disturbances were more pronounced after stasis.Venous insufficiency can be characterized by alteration of rheological parameters and the blood stasis in varicose veins may enhance these alterations. These results indicate the importance of hemorheological disturbances in the pathogenesis of this disease.