Instability of emulsions under stress conditions can be related to normal shelf life. Start studying pharmaceutics colloids, suspensions, emulsions and rheology. Ii suspensions, emulsions and foams pier luca maffettone, francesco greco encyclopedia of life support systems eolss the actual particle dimension is irrelevant, and all macroscopic observables in the dilute case will only depend on the low solid volume fraction. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Thixotropy is useful in the formulation of pharmaceutical suspensions and emulsions. Shear viscosity of concentrated suspensions of viscoelastic particles in concentrated suspensions, hydrodynamic interactions enhance shear gradients and particle deformation but the flowinduced anisotropic microstructures lead to a decrease in viscous dissipation and suspension apparent viscosity. Examples of suspensions include both natural and manmade materials for instance, ink as a suspension of pigments of dyes of typically 5 10. This webinar will showcase the power of rheomicroscopy for an accurate interpretation of rheological data in the context of three case studies, each on a different material and using a different rheometry technique. An introduction to colloidal suspension rheology youtube.
The study of rheology can be used to evaluate the behavior of particles in a liquid vehicle. Flow in pipelines and constraining media applications in pipeline flow. An illustration of the types of shear induced orientation which can occur for various shear thinning materials is shown in figure 4. The issue of rheology in food emulsions is closely linked to the texture, taste, and mouth feel of foods obtained from these emulsions. The rheology of suspensions of solid particles proceedings of the. The rheology of these dense suspensions can be approached via a diversity of approaches that the paper introduces successively. Models for the interpretation of rheological results. A generalized equation for rheology of emulsions and suspensions of deformable particles subjected to simple shear at low reynolds number article pdf available in rheologica acta november. Ii food rheology mats stading encyclopedia of life support systems eolss food rheology mats stading sik the swedish institute for food and biotechnology and chalmers university of technology, gothenburg, sweden keywords. In the limiting case of dilute emulsions, the discussion is based on the analogy keywords.
The suspensions exhibited newtonian behavior at low solids volume fractions. A basic introduction to rheology rheology and viscosity introduction. Rheology and structure of emulsions and suspensions request pdf. It applies to substances which have a complex structure, including muds, sludges, suspensions. Rheology of concentrated suspensions of viscoelastic. The stress conditions normally employed for evaluating the stability of emulsions include. Rheology and structure of emulsions and suspensions. Deformability of the interface, together with breakup and coalescence phenomena play. Ii suspensions, emulsions and foams pier luca maffettone, francesco greco. Rheology of suspensions colloid suspension chemistry.
A discussion of the rheology of suspensions and how it relates to that of emulsions is given. Emulsion formation, stability, and rheology tharwat f. The second section reports on the rheology of liquidliquid suspensions, i. These multiparticle systems are subjected to a steady straining flow at low. Several factors can easily affect the rheology of emulsions and it may be considered that they are related to the properties of the phases. Many pharmaceutical products are produced in the form of a suspension. University of mauritius bachelor of pharmacy year 2 pharmaceutics iii title. For example, emulsions occur as oil in water ow emulsions or water in oil wo emulsions. During the laboratory exercise, students learned the proper use of a. The mixture of particles and fluid can be seen as a fluid with effective rheological properties but also as a twophase system wherein the fluid and particles can experience relative motion. Solids are said to have an elastic response, and can resist.
The ow emulsions, containing 5 vol of the dispersed phase, the oil phase was colored with red dye, scarlet b. Emulsions rheology of suspensions many pharmaceutical products, particularly those for children, are presented as suspension and their rheological properties are important. Hubbe, a pegah tayeb, a michael joyce, a preeti tyagi, a margaret kehoe, a,b katarina dimicmisic, c and lokendra pal a the flow characteristics of dilute aqueous suspensions of cellulose nanocrystals cnc, nanofibrillated cellulose nfc, and related products in dilute aqueous suspensions could be of great. These multiparticle systems are subjected to a steady straining flow at low reynolds number. Food, biopolymers, colloids, foam, emulsion, suspension, processing, rheometry, gel. By recasting our data in terms of the einstein coefficient, we relate our rheological observations to the underlying particle motions via jefferys jeffery 1922 proc.
The emulsions had the oil volume fraction in the range from 0. The shear rheology of an emulsion of viscous drops in the presence of finite inertia is investigated using direct numerical simulation. This study compared the effects of oil concentration and. Coarse dispersions suspensions emulsions suspensions a pharmaceutical suspension is a coarse dispersion in which insoluble solid particles are dispersed in a liquid medium. In the limiting case of dilute emulsions, the discussion is based on the analogy and differences in properties of suspensions and emulsions. Understanding the principles that govern the flow characteristics of the dispersions is essential for formulating a dispersion and its longterm stability1,2. The viscosity of semisolid products may affect absorption of these topical products due to the effect of viscosity on the rate of diffusion of the active ingredients.
Pdf rheology of emulsions svetlana derkach academia. Click download or read online button to get rheology of pharmaceutical emulsions book now. The rheological behavior of particleoil suspensions and wo pickering emulsions consisting of water, 1dodecene and different fumed silica nanoparticles was investigated. Rheology of systems with soft or electrostatic interaction. The liquid droplets the disperse phase are dispersed in a liquid medium the continuous phase. Emulsions have been widely used in different industrial processes. The elastic modulus of individual oilfilled microgel particles will influence the bulk modulus of the microgel suspension. The laos analysis of hardsphere suspensions provides useful guidance for understanding the response of related, but more complex, materials such as gels, clay dispersions, and emulsions. Rheology of suspensions and emulsions authorstream presentation. Increasing the zeroshear viscosity of the continuous phase of an emulsion or suspension is a popular method of increasing physical stability. Its application to suspensions of hard and soft particles would allow insight into their different rheology and yielding that is a direct result of the elastic properties of the constituent particles. Oscillatory rheology measuring the viscoelastic behaviour of soft materials measuring this time dependent stress response at a single frequency immediately reveals key differences between materials, as shown schematically in figure 1b.
It applies to substances which have a complex structure, including muds, sludges, suspensions, polymers, many foods, bodily. The rate of absorption of an ordinary suspension differs from thixotropic suspension. Uniform electricfieldinduced nonnewtonian rheology of a dilute suspension of deformable newtonian drops. Rheology of attractive emulsions harvard university. A generalized equation for rheology of emulsions and. Suspensions are usually dispensed in bottles or sachets and are taken from a spoon. This article contains the results of experimental investigation of the rheological characteristics and structures of emulsions and suspensions. The emulsions of kerosene in water were shearthinning over the oil volume fraction range of 0. Viscosity of a structured fluid as a function of shear rate and particle concentration1. Inertial effects on the rheology of a dilute emulsion volume 646 r. Rheology centre rheology analysis viscosity testing. Pdf emulsion types, stability mechanisms and rheology. The relevance of the dynamic nature of the interface is stressed throughout, from the disperse to the cocontinuous morphology.
A generalized equation for rheology of emulsions and suspensions. The rheological behavior of clay suspensions, oilinwater emulsions, and their blends was investigated using a controlledstress rheometer. Monodisperse colloidal hard sphere suspensions have been studied thoroughly for the case. A generalized equation for rheology of emulsions and suspensions of deformable particles subjected to simple shear at low reynolds number. Influence of nonionic surfactant addition on the stability and rheology of particlestabilized emulsions. Figure 2 indicates the different types of emulsions. Request pdf rheology and structure of emulsions and suspensions this article contains the results of experimental investigation of the rheological. A basic introduction to rheology rheology and viscosity introduction rheometry refers to the experimental technique used to determine the rheological properties of materials. Rheology of suspensions and emulsions rheology emulsion. The emulsion showed a pseudoplastic flow whereas the suspension exhibited a plastic profile.
In general these properties must be considered so that. The product is easily administered from bottle or via syringe needle 2. Rheology on the way from dilute to concentrated emulsions. Rheology of pharmaceutical emulsions download ebook pdf. Rheological measurements of compounded emulsions and.
An important challenge then is to link the microscopic singleparticle modulus directly to the macroscopic suspension rheology. Rheology and structure of emulsions and suspensions article in journal of dispersion science and technology 332. Rheology of suspensions rheology of dispersions wiley. The development and production of good quality emulsions depend on the knowledge of emulsion preparation, stability mechanisms. Food rheology encyclopedia of life support systems. Application note rheology of pharmaceutical suspensions. Between 1966 and 1969, he spent a sabbatical at the agricultural university of wageningen and t. In the absence of inertia, emulsions display a nonnewtonian rheology with positive first and negative second normal stress differences.
Hubbe, a pegah tayeb, a michael joyce, a preeti tyagi, a margaret kehoe, a,b katarina dimicmisic, c and lokendra pal a. Understanding rheology of structured fluids keywords. This webinar will showcase the power of rheomicroscopy for an accurate interpretation of rheological data in the context of three case studies, each on a different material and using a. The rheological behavior of materials can be regarded as being between two extremes. Rheology of suspensions factors considered are viscosity of a suspension change in flow properties of the suspension spreading qualities of. According to its definition, rheology is the science of the deformation and flow of mater. The reader will quickly appreciate the breadth of the subject area and, furthermore, that mastering colloidal suspension rheology requires some basic knowledge in colloid science as well as rheology. This site is like a library, use search box in the widget to get ebook that you want. Rheology of emulsions advances in chemistry acs publications.
Rheology is the study and control of the flow properties1,2. Practical re commendations for shelf life predictions of emulsions. To the pharmacist, rheology is important in the flow of emulsions, through colloid mills, triturating suspensions in mortar and pestle and mechanical properties of glass or plastic containers and of rubber closures. We present analyses to provide a generalized rheological equation for suspensions and emulsions of nonbrownian particles. Rheology of suspensions free download as powerpoint presentation. Note that in all cases the terms oil and water are used in a broad sense, i. Rheology of emulsionfilled alginate microgel suspensions. Rheology of emulsions performance of the emulsion depends on flow properties removal of an emulsion from a bottle or tube flow of an emulsion through a hypodermic needle. We present data for the rheology of suspensions of monodisperse particles. Help solve your surfactant, emulsion, foam, and suspension problems in this course designed for scientists and engineers engaged in research and development in the chemical, petroleum, coatings, food, electronics, pharmaceutical, cosmetics, and personal care products industries. Elasticities of attractive and repulsive emulsions differ below random close packing but are similar above it.
Understanding rheological properties of suspensions and how particle characteristics are controlling factors given the complementary range of materials characterization techniques we have here at malvern, the measurement of dispersed systems from suspensions, emulsions and foams, to pastes and gels is something that we are very familiar. It is usually caused by large velocity gradients in a thin region adjacent to the wall. Rheology on the way from dilute to concentrated emulsions s. Rheology testing can be used as a rapid test for suspension stability, by looking at zero shear viscosity characteristics to look at sedimentation velocity. The effect of added solids to an emulsion is fully treated, and its relation to a bimodel system is.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Effect of adsorbed polyethylene oxide on the rheology of colloidal silica suspensions. Rheology of concentrated soft and hardsphere suspensions. Pdf a generalized equation for rheology of emulsions and. Available formats pdf please select a format to send. Surface avg particle diameter of internal phase was determined by microscope. Nonlinear rheology of colloidal suspensions probed by. A basic introduction to rheology technology networks. Inertial effects on the rheology of a dilute emulsion.
The rheological properties of both liquid and semisolid. Feb 26, 2018 rheology is the study and control of the flow properties1,2. Rheology of dense granular suspensions journal of fluid. These relationships can be used to predict the rheology of suspensions of prolate particles from measured. The suspensions with nanoparticles are represented by suspensions of silica with concentrations from 1 to 4%.
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