These emulsions, which are known as high internal phase ratio emulsions hipre, gel emulsions, biliquid foams, etc. Rheological properties of concentrated oil in water emulsions containing dissolving polymers in both phases, partially playing a role of surfactants, were studied. The practical insolubility of carbon nanotubes cnts in aqueous and organic media necessitates the disentanglement of cnt agglomerates through the utilization of. Study on the flow of highly concentrated emulsions. Rheology of disperse systems is an extremely important processing parameter. The rheology of highly concentrated emulsions stabilized with. However, this refining effect lasted for just a short time.
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. The concentration and size dependencies of elastic properties of highly concentrated wo emulsions were studied. Formulation and investigation of gelemulsions containing. Anomalous viscous loss in emulsions harvard university.
Shear stability of waterinoil highly concentrated emulsions was characterized by the rate of the droplet size decrease at a constant shear rate. 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. Buitenhuis j 2003 negative thixotropy of polymer solutions a model explaining timedependent viscosity. Request pdf rheopexy in highly concentrated emulsions this work describes a detailed study of the theopectic effect in the flow of highly concentrated. S2 sem image of a polymerized sample after catastrophic inversion from a highly concentrated pickering wo to a ow diluted pickering emulsion. Water phase concentration approximately 91% consists of a supersaturated aqueous solution of nitrate salts. Rheopexy in highly concentrated emulsions request pdf. Homogeneous and selective dispersions of mwcnts throughout the oil phase of the emulsions are investigated. A dispersion is a system of unmixable phases in which one phase is continuous and at least one is finely distributed. Apr 30, 2018 the problem of shear stability of highly concentrated dense emulsions has been discussed based on treating these emulsions as viscoplastic media.
The structure recovery capacity of highly concentrated. Rheological properties of highly concentrated emulsions of the waterinoil type were studied. 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. Effect of droplet size on the rheological properties of. It was found that the emulsions are nonnewtonian liquids and flow curves measured in a.
This concentration was related to full coverage of the droplet interface. Additionally, nanoparticles were added to the aqueous phase, and they had an influence on rheological behavior and emulsion stability. Using pxrd to investigate the crystallization of highly concentrated emulsions of nh 4 no 3 e. Although they also investigated oil in water emulsions they did not published the results. Physicochemical and engineering aspects on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Stability and characterisation of emulsions in the presence of colloidal particles and surfactants by roman pichot a thesis submitted to the university of birmingham. It was proven by various experimental techniques that aging leads to the emulsion tosuspension transition.
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. Capillary breakup extensional rheometry caber on semi. The rheological properties of highly concentrated emulsions have been the subject of many studies. Sheardriven activation, aggregation, and rheopexy in. Using pxrd to investigate the crystallization of highly. 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. 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.
Further, rheopexy may even lead, under certain conditions, to a liquidsolid. The technique has been applied to various kinds of complex fluids including carbon nanotube suspensions tiwari et al. Rheopexy in highly concentrated emulsions journal of rheology. Emulsion stability of cosmetic creams based on waterinoil. This is an extract of the complete reprintpdf, available at the applied rheology website.
Soltero j 1995 thixotropicantithixotropic behavior of surfactantbased lamellar liquid crystals under shear flows. The upward experiments show the existence of the newtonian part on the flow curve in the lowshearrate domain, while. Emulsion stability of cosmetic creams based on water in oil high internal phase emulsions koreaaustralia rheology journal september 2003 vol. Shear rheometers can be divided into rotational rheometers, in which the shear is generated between. 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. Experiments with the shear rate sweep demonstrated that the upward and do.
Structure of flocculated droplets in a dilute emulsion and b concentrated. The aqueous phase volume content was varied from 1 to 40%, and the temperature was varied from 0 to 30. Biomolecules free fulltext rheopectic behavior for. Recent interest in utilizing lipid emulsions for delivering lipid soluble therapeutic agents. Experiments with the shear rate sweep demonstrated that the upward and downward branches of the flow curves coincide above some specific shear rate value. When a force is applied to a liquid, the liquid will. The structure recovery capacity of highly concentrated emulsions.
Coalescence proceeded until the internal area of the emulsion was. Masalova i 2006rheology of super concentrated emulsions, world congress on emulsions, 26 october, lyon, france, keynote lecture, full paper published in proceedings. Emulsification of highly concentrated emulsionsa criterion. Finally, typical features of emulsion rheology will be discussed with special emphasis on the distinct differences between dispersion and emulsion rheology. 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. Gel emulsions, besides microemulsion gels and creams, belong to coherent emulsions. The yield stresses of five samples two highly concentrated emulsions, two kaolin dispersions and. Highly concentrated inverse anionic polymeric emulsions with a solid content of up to 63 wt % were prepared using a two. Macroporous polymers obtained in highly concentrated. This work describes a detailed study of the rheopectic effect in the flow of highly concentrated emulsions at low stresses. In this study, oilinwater ow emulsions with two surfactantwater sw weight ratios of 40. Examples are found in many industrial applications, including emulsions, suspensions, foams, and geld. Extensional viscosity measurements of concentrated emulsions with.
Viscosity of a structured fluid as a function of shear rate and particle concentration1. Mikami y 1982 interpretation of the rheopexy by a two process kinetic model. Jun 24, 2005 this work describes a detailed study of the rheopectic effect in the flow of highly concentrated emulsions at low stresses. Stability and characterisation of emulsions in the.
Foams and highly concentrated emulsions are examples of such jammed and yet not fragile systems. Thermal properties of noncrystallizable oilinwater highly concentrated emulsions. The problem of droplet size dependence on rheological properties of highly concentrated emulsions was studied. Masalova2 adepartment of chemistry, nelson mandela metropolitan university, p. Rheology of highly concentrated emulsions concentration and droplet size dependencies. 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.
The range of weight concentration of the disperse phase was 90 96%, the range of the average droplet size was. Effect of organic modification on multiwalled carbon. The operating speed of the blade stirrer with 2 blades. Mar 17, 2020 the structure recovery capacity of highly concentrated emulsions under shear flow via studying their rheopexy. Being able to characterize and manipulate the flow behavior of dispersions one can ensure their optimal performance. Masalova i 2005 rheopexy in highly concentrated emulsions.
An investigation was performed into the structure recovery of highly concentrated waterinoil emulsions hces under shear flow via studying their rheopexy. 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 influence of thickeners on the rheological and sensory. The average size of droplets, d, in the emulsions was varied. Understanding rheology of structured fluids keywords. Rheology on the way from dilute to concentrated emulsions. Structure determination of a highly concentrated wo. 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. Masalova i 2006flow and elasticity of highly concentrated emulsions, annual meeting of swiss rheology society, 2022 october, freiburg, switzerland, keynote lecture. Refractive index was measured using an abbe refractometer atago, japan. Emulsion formation, stability, and rheology tharwat f. Negative thixotropy is a time dependent increase in the viscosity at constant shear.
Introduction emulsions are a multicomponent compounds formed by liquid droplets dispersed inside a liquid medium. The rheology of highly concentrated emulsions stabilized with different surfactants. Effect of droplet size on the rheological properties of highly concentrated wo emulsions. Rheological properties of highly concentrated emulsions of the water in oil type were studied. Evolution of rheological properties of highly concentrated. 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. They presented measurement results for concentrated water in oil emulsions in extensional flow using a.
Structure and rheology of highly concentrated emulsions. Pdf effect of droplet size on the rheological properties of highly. Rheopectic behavior for aqueous solutions of megamolecular. Highly concentrated emulsion an overview sciencedirect. Preparation of highly concentrated inverse emulsions of. The presence of emulsions reduces the quality of crude oil. Extensional viscosity measurements of concentrated. The preparation of emulsions requires energy to disperse the organic phase solvent or solution in water. Although they also investigated oilinwater emulsions they did not published the results. 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. 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.
This is a promising new field of study, already being implemented by manufacturers and actively developing. In the row of technological materials, emulsions occupy a position between suspensions and foams. Diffractionlike effects have been observed by applying pulsedfieldgradient spin. This study was focused on coalescence in highly concentrated emulsions stabilized by a whey protein isolate or by sodium dodecyl sulfate.
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. Highly macroporous composite polymers were obtained by polymerization in the external phase of these emulsions. 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. G, provided by the particular dispersing procedure at constant composition and pressure, can be. After that, the structure of highly concentrated emulsion hce. An investigation was performed into the flow of highly concentrated waterinoil emulsions hces. Coalescence in highly concentrated coarse emulsions langmuir. Highly concentrated waterinoil emulsions incorporating multiwalled carbon nanotubes mwcnts are prepared. The upward experiments show the existence of the newtonian part on the flow curve in the lowshearrate. The focus of this present study is to investigate and lay the ground work for further research.
In order to get an idea about the thermodynamics the change in the gibbs free energy of the system. Starting with dilute and semidilute emulsions, one can see that the main subject of investigation was the concentration dependence of viscosity, as studied in numerous publications 18 6. For both stabilizers, coalescence of the emulsion at rest occurred below a critical concentration of the stabilizer. The main peculiarity of the objects is the superposition of viscoelastic properties related to. The effect of aqueous phase content and temperature north sea crude oil emulsion viscoelastic behavior has been studied. Another study dealing with extensional viscosity was reported by niedzwiedz et al. Highly concentrated bitumen emulsions a state of the art. The viscosity of low shear rate region in downward curve was much higher than the viscosity of. Suspensions containing 1 to 10% of dispersed solids generally show negative thixotropy.
Possibilities to form a gelemulsion are the following. The rheology of highly concentrated emulsions stabilized. Heavy crude oil from the north sea is of high viscosity and is capable of forming stable. Yield stress as measured in steady shearing and in oscillations. The emulsions under study are viscoplastic media with a clearly expressed yield stress.
Binary mixtures of highly concentrated emulsions hce with three droplet size ratios and different compositions were prepared. The liquid droplets the disperse phase are dispersed in a liquid medium the continuous phase. An investigation was performed into the structure recovery of highly concentrated waterinoil emulsions hces under shear flow via studying on their rheopexy. Changes in droplet size distribution were achieved by multipass flow through a small.
S1 thermogravimetric analysis in which the total oleic acid content attached to the particle surfaces is derived from the curves. In particular, rheopexy, as a consequence of aggregation under shear, is observed in important biological fluids such as protein solutions e. Feb 05, 2011 read the rheology of highly concentrated emulsions stabilized with different surfactants, colloids and surfaces a. On the other hand, a paper for highly concentrated emulsion by zhao et al. Significant shift of rheological properties to the solidlike behavior is the result of the emulsions. 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. Highly concentrated emulsions, elasticity and plasticity i. Rheoviscometry of offset inks and their emulsions with water. The range of weight concentration of the disperse phase was 90 96%, the range of. The qspace plots of the pfgse nmr data show one pronounced maximum and the shoulder of a second maximum in the. Some emulsions adhesive remain stable whereas another type of emulsions nonadhesive relax and the volume fraction of.
Rheology of highly concentrated emulsions concentration and. Extensional viscosity measurements of concentrated emulsions. Abstractan investigation was performed into the flow of highly concentrated waterinoil emulsions. 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. Abstractan investigation was performed into the flow of highly concentrated water in oil emulsions.
Escalante j 2000 nonlinear rheology and flow induced transition to a lamellar. Princen lever brothers research center, 45 river road, edgewater, new jersey 07020 received march 5, 1979. Highly concentrated emulsions hces are a mixture of two. In recent years, using mixtures of different surfactants to stabilize concentrated and highly concentrated emulsions has become rather popular 4649. The problem of shear stability of highly concentrated dense emulsions has been discussed based on treating these emulsions as viscoplastic media. 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. 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. Shear and normal stresses in flow of highly concentrated. Rheology of highly concentrated emulsions concentration. Moreover, emulsions affect general flow behavior of the fluid and can lead to significant flow assurance problems 4,5,6,7. A tomato juice containing 1% soy protein demonstrates a rheopectic behavior at shear rates lower than 250 s1 due to. Physical chemistry of highly concentrated emulsions.
Injectable lipid emulsionsadvancements, opportunities and. Pdf effect of droplet size on the rheological properties. Dilute emulsions behave as viscous liquids, whereas concentrated emulsions exhibit solidlike elasticity. 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.
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