Escalante j 2000 nonlinear rheology and flow induced transition to a lamellar. After that, the structure of highly concentrated emulsion hce. The practical insolubility of carbon nanotubes cnts in aqueous and organic media necessitates the disentanglement of cnt agglomerates through the utilization of. Recent interest in utilizing lipid emulsions for delivering lipid soluble therapeutic agents. When a force is applied to a liquid, the liquid will.
Abstractan investigation was performed into the flow of highly concentrated water in oil emulsions. S1 thermogravimetric analysis in which the total oleic acid content attached to the particle surfaces is derived from the curves. Although they also investigated oil in water emulsions they did not published the results. Finally, typical features of emulsion rheology will be discussed with special emphasis on the distinct differences between dispersion and emulsion rheology. A dispersion is a system of unmixable phases in which one phase is continuous and at least one is finely distributed. Stability and characterisation of emulsions in the. Rheology of disperse systems is an extremely important processing parameter. Oct 26, 2010 injectable lipid emulsions, for decades, have been clinically used as an energy source for hospitalized patients by providing essential fatty acids and vitamins. Some emulsions adhesive remain stable whereas another type of emulsions nonadhesive relax and the volume fraction of. While fragile matter responds to a shear stress plastically, foams and hces show an elastic behavior below a stress threshold, which is known as the yield 5.
The rheology of binary mixtures of highly concentrated. Preparation of highly concentrated inverse emulsions of. Instability of highly concentrated emulsions of the waterinoil type which were investigated in this work is related to the existence of the internal phase as an oversaturated salt solution in water. Emulsification of highly concentrated emulsionsa criterion. In this study, oilinwater ow emulsions with two surfactantwater sw weight ratios of 40. Request pdf rheopexy in highly concentrated emulsions this work describes a detailed study of the theopectic effect in the flow of highly concentrated. The range of weight concentration of the disperse phase was 90 96%, the range of the average droplet size was. The range of weight concentration of the disperse phase was 90 96%, the range of. Highly concentrated inverse anionic polymeric emulsions with a solid content of up to 63 wt % were prepared using a two. Shear and normal stresses in flow of highly concentrated.
The main peculiarity of the objects is the superposition of viscoelastic properties related to. Evolution of rheological properties of highly concentrated. Emulsion stability of cosmetic creams based on waterinoil. Using pxrd to investigate the crystallization of highly. Their rheological properties were characterized by the linear elastic modulus and the yield stress because these properties are responsible for the rheological properties of emulsion. Anomalous viscous loss in emulsions harvard university. Foams and highly concentrated emulsions are examples of such jammed and yet not fragile systems. The rheological properties of interface and emulsion stability can be varied by using different surfactants and by combining various surfactant pairs to provide intermolecular interaction 50. Princen lever brothers research center, 45 river road, edgewater, new jersey 07020 received march 5, 1979. Significant shift of rheological properties to the solidlike behavior is the result of the emulsions. Rheological properties of highly concentrated emulsions of the water in oil type were studied. The structure recovery capacity of highly concentrated. Experiments with the shear rate sweep demonstrated that the upward and downward branches of the flow curves coincide above some specific shear rate value.
This study was focused on coalescence in highly concentrated emulsions stabilized by a whey protein isolate or by sodium dodecyl sulfate. The effect of aqueous phase content and temperature north sea crude oil emulsion viscoelastic behavior has been studied. Emulsion stability of cosmetic creams based on water in oil high internal phase emulsions koreaaustralia rheology journal september 2003 vol. The operating speed of the blade stirrer with 2 blades. Rheology on the way from dilute to concentrated emulsions. Using pxrd to investigate the crystallization of highly concentrated emulsions of nh 4 no 3 e. An investigation was performed into the structure recovery of highly concentrated waterinoil emulsions hces under shear flow via studying their rheopexy. This work describes a detailed study of the rheopectic effect in the flow of highly concentrated emulsions at low stresses.
Highly concentrated emulsion an overview sciencedirect. Understanding rheology of structured fluids keywords. Biomolecules free fulltext rheopectic behavior for. Gel emulsions, besides microemulsion gels and creams, belong to coherent emulsions. The author assumes no prior knowledge of colloid chemistry and, with its glossary of key terms, complete crossreferencing and indexing, this is a musthave for graduate and professional scientists and engineers who may encounter or use emulsions, foams, or suspensions, or combinations thereof, whether in process design, industrial production. Rheopexy in highly concentrated emulsions journal of rheology.
Masalova2 adepartment of chemistry, nelson mandela metropolitan university, p. Being able to characterize and manipulate the flow behavior of dispersions one can ensure their optimal performance. Jun 24, 2005 this work describes a detailed study of the rheopectic effect in the flow of highly concentrated emulsions at low stresses. Diffractionlike effects have been observed by applying pulsedfieldgradient spin. Water in oil emulsions are one of the major problems in the petroleum industry has to deal with during recovery, treatment, and transportation of crude oil 2,3.
G, provided by the particular dispersing procedure at constant composition and pressure, can be. Extensional viscosity measurements of concentrated emulsions with. Mar 17, 2020 the structure recovery capacity of highly concentrated emulsions under shear flow via studying their rheopexy. Masalova i 2005 rheopexy in highly concentrated emulsions. An investigation was performed into the flow of highly concentrated waterinoil emulsions hces. Shear rheometers can be divided into rotational rheometers, in which the shear is generated between. Soltero j 1995 thixotropicantithixotropic behavior of surfactantbased lamellar liquid crystals under shear flows. The concentration and size dependencies of elastic properties of highly concentrated wo emulsions were studied. Rheological properties of concentrated oil in water emulsions containing dissolving polymers in both phases, partially playing a role of surfactants, were studied. Yield stress as measured in steady shearing and in oscillations.
Study on the flow of highly concentrated emulsions. Possibilities to form a gelemulsion are the following. Experiments with the shear rate sweep demonstrated that the upward and do. Macroporous polymers obtained in highly concentrated. Although they also investigated oilinwater emulsions they did not published the results. Water phase concentration approximately 91% consists of a supersaturated aqueous solution of nitrate salts. Not available bibtex entry for this abstract preferred format for this abstract see preferences find similar abstracts. Read the rheology of highly concentrated emulsions stabilized with different surfactants, colloids and surfaces a. Additionally, nanoparticles were added to the aqueous phase, and they had an influence on rheological behavior and emulsion stability. Rheology of highly concentrated emulsions concentration and. The rheological properties of highly concentrated emulsions have been the subject of many studies. Viscosity of a structured fluid as a function of shear rate and particle concentration1. This is an extract of the complete reprintpdf, available at the applied rheology website. It was found that the emulsions are nonnewtonian liquids and flow curves measured in a.
Capillary breakup extensional rheometry caber on semi. In recent years, using mixtures of different surfactants to stabilize concentrated and highly concentrated emulsions has become rather popular 4649. Nov 15, 2007 shear and normal stresses in flow of highly concentrated emulsions shear and normal stresses in flow of highly concentrated emulsions malkin, alexander ya masalova, irina 20071115 00. An investigation was performed into the structure recovery of highly concentrated waterinoil emulsions hces under shear flow via studying on their rheopexy. Nov 15, 2007 investigations of highly concentrated emulsions showed that these materials demonstrate some unusual rheological effects, such as rheopexy in the low shear rate domain, emulsiontosuspension transition with changes in rheological properties in aging, and others. The influence of thickeners on the rheological and sensory. This concentration was related to full coverage of the droplet interface. The focus of this present study is to investigate and lay the ground work for further research. The aqueous phase volume content was varied from 1 to 40%, and the temperature was varied from 0 to 30. Buitenhuis j 2003 negative thixotropy of polymer solutions a model explaining timedependent viscosity. The problem of droplet size dependence on rheological properties of highly concentrated emulsions was studied. Introduction emulsions are a multicomponent compounds formed by liquid droplets dispersed inside a liquid medium.
Stability and characterisation of emulsions in the presence of colloidal particles and surfactants by roman pichot a thesis submitted to the university of birmingham. The emulsions under study are viscoplastic media with a clearly expressed yield stress. Emulsion formation, stability, and rheology tharwat f. Extensional viscosity measurements of concentrated emulsions. Apr 30, 2018 the problem of shear stability of highly concentrated dense emulsions has been discussed based on treating these emulsions as viscoplastic media. For both stabilizers, coalescence of the emulsion at rest occurred below a critical concentration of the stabilizer. Structure of flocculated droplets in a dilute emulsion and b concentrated. Effect of organic modification on multiwalled carbon. The viscosity of the low shear rate region in the downward curve was much higher than the viscosity of the upward curve due to the refining effect of the intensive shear. The rheology of highly concentrated emulsions stabilized with. Examples are found in many industrial applications, including emulsions, suspensions, foams, and geld. Coalescence proceeded until the internal area of the emulsion was.
Effect of droplet size on the rheological properties of highly concentrated wo emulsions. Effect of droplet size on the rheological properties of. Changes in droplet size distribution were achieved by multipass flow through a small. It was found that by the proper selection of droplet size ratio and composition of binary mixtures, the shear modulus, viscosity, yield stress, and yield strain can be dropped lower than mixing rules and even primary hce. Moreover, emulsions affect general flow behavior of the fluid and can lead to significant flow assurance problems 4,5,6,7. The presence of emulsions reduces the quality of crude oil. Shear stability of waterinoil highly concentrated emulsions was characterized by the rate of the droplet size decrease at a constant shear rate. Pdf effect of droplet size on the rheological properties of highly. The rheology of highly concentrated emulsions stabilized with different surfactants. The average size of droplets, d, in the emulsions was varied. Negative thixotropy is a time dependent increase in the viscosity at constant shear. This is a promising new field of study, already being implemented by manufacturers and actively developing. Such different abilities to migrate to the interface had significant effects on the maximum internal phase fraction achievable and the droplet size distribution of the emulsions.
On the other hand, a paper for highly concentrated emulsion by zhao et al. Formulation and investigation of gelemulsions containing. Homogeneous and selective dispersions of mwcnts throughout the oil phase of the emulsions are investigated. The viscosity of low shear rate region in downward curve was much higher than the viscosity of. Rheological properties of highly concentrated emulsions of the waterinoil type were studied.
Masalova i 2006flow and elasticity of highly concentrated emulsions, annual meeting of swiss rheology society, 2022 october, freiburg, switzerland, keynote lecture. Rheology of highly concentrated emulsions concentration and droplet size dependencies. Investigations of highly concentrated emulsions showed that these materials demonstrate some unusual rheological effects, such as rheopexy in the low shear rate domain, emulsion tosuspension transition with changes in rheological properties in aging, and others. Refractive index was measured using an abbe refractometer atago, japan. Masalova i 2006rheology of super concentrated emulsions, world congress on emulsions, 26 october, lyon, france, keynote lecture, full paper published in proceedings. The upward experiments show the existence of the newtonian part on the flow curve in the lowshearrate. Shear and normal stresses in flow of highly concentrated emulsions shear and normal stresses in flow of highly concentrated emulsions malkin, alexander ya masalova, irina 20071115 00. In particular, rheopexy, as a consequence of aggregation under shear, is observed in important biological fluids such as protein solutions e. The liquid droplets the disperse phase are dispersed in a liquid medium the continuous phase. Heavy crude oil from the north sea is of high viscosity and is capable of forming stable. Feb 05, 2011 read the rheology of highly concentrated emulsions stabilized with different surfactants, colloids and surfaces a.
Another study dealing with extensional viscosity was reported by niedzwiedz et al. The effect of aging on the rheological properties and physical structure of highly concentrated waterinoil emulsions with dispersed phase of 82 90 v % is the subject of this study. Rheoviscometry of offset inks and their emulsions with water. The upward experiments show the existence of the newtonian part on the flow curve in the lowshearrate domain, while. A tomato juice containing 1% soy protein demonstrates a rheopectic behavior at shear rates lower than 250 s1 due to. The preparation of emulsions requires energy to disperse the organic phase solvent or solution in water. These emulsions, which are known as high internal phase ratio emulsions hipre, gel emulsions, biliquid foams, etc. Abstractan investigation was performed into the flow of highly concentrated waterinoil emulsions. Highly concentrated emulsions hces are a mixture of two.
Mikami y 1982 interpretation of the rheopexy by a two process kinetic model. Structure determination of a highly concentrated wo. The structure recovery capacity of highly concentrated emulsions. Structure and rheology of highly concentrated emulsions. Dilute emulsions behave as viscous liquids, whereas concentrated emulsions exhibit solidlike elasticity. Sheardriven activation, aggregation, and rheopexy in. The technique has been applied to various kinds of complex fluids including carbon nanotube suspensions tiwari et al. Further, rheopexy may even lead, under certain conditions, to a liquidsolid.
Definitions an emulsion is a two phase system consisting of two incompletely miscible liquids, one of which is dispersed as finite globules in the other. The yield stresses of five samples two highly concentrated emulsions, two kaolin dispersions and. It was proven by various experimental techniques that aging leads to the emulsion tosuspension transition. Rheopexy is the phenomenon where sol forms a gel more rapidly when gently shaken than when allowed to form the gel by keeping the material. Physical chemistry of highly concentrated emulsions. Rheopectic behavior for aqueous solutions of megamolecular.
Thermal properties of noncrystallizable oilinwater highly concentrated emulsions. They presented measurement results for concentrated water in oil emulsions in extensional flow using a. Rheopexy in highly concentrated emulsions request pdf. Physicochemical and engineering aspects on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Pdf effect of droplet size on the rheological properties. Suspensions containing 1 to 10% of dispersed solids generally show negative thixotropy. Instability of highly concentrated emulsions of the water in oil type which were investigated in this work is related to the existence of the internal phase as an oversaturated salt solution in water. In order to get an idea about the thermodynamics the change in the gibbs free energy of the system. Coalescence in highly concentrated coarse emulsions langmuir. Highly concentrated emulsions, elasticity and plasticity i. The problem of shear stability of highly concentrated dense emulsions has been discussed based on treating these emulsions as viscoplastic media.
Highly macroporous composite polymers were obtained by polymerization in the external phase of these emulsions. However, this refining effect lasted for just a short time. Highly concentrated bitumen emulsions a state of the art. S2 sem image of a polymerized sample after catastrophic inversion from a highly concentrated pickering wo to a ow diluted pickering emulsion. The rheology of highly concentrated emulsions stabilized. Binary mixtures of highly concentrated emulsions hce with three droplet size ratios and different compositions were prepared. In the row of technological materials, emulsions occupy a position between suspensions and foams. Injectable lipid emulsionsadvancements, opportunities and. Heavy crude oil from the north sea is of high viscosity and is capable of forming stable waterincrude oil wo emulsions without introducing any synthetic surfactants. Rheology of highly concentrated emulsions concentration. The influence of thickeners on rheological and sensory properties of cosmetic lotions 174 choice of the corresponding absolute or universal scales, and suitable choice of a professional panel expensive. The qspace plots of the pfgse nmr data show one pronounced maximum and the shoulder of a second maximum in the. Extensional viscosity measurements of concentrated. Highly concentrated waterinoil emulsions incorporating multiwalled carbon nanotubes mwcnts are prepared.
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