Download or read book Effect of Attractions on the Flow Properties of Dense Colloidal Suspensions written by Vijay Gopalakrishnan and published by . This book was released on 2004 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Confined Flow of Attractive Colloidal Suspensions written by Rahul Pandey and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Attractive particulate fluids flowing through complex confined geometries are frequently used in technological applications. While the flow properties of hard-sphere suspensions in micro-scale geometries have been studied extensively, the effects of interparticle attractions and particle size dispersity on the confined flow properties of particulate suspensions are not well understood. We used confocal microscopy, particle tracking, and bulk rheology to study the confined structure, dynamics, and flow properties of colloid-polymer mixtures, which serve as simple models of attractive particulate suspensions. We employed poly(methyl-methacrylate) spheres that were suspended in a refractive-index and density- matched solvent, and induced a controlled short-range depletion attraction between particles by adding non-absorbing linear polystyrene. First, we investigated the effects of particle size dispersity on confinement-induced solidification of colloid-polymer mixtures. We formulated mixtures of polymer and bidispersed colloids with particle size ratio aS/aL ≈ 0.49 at a constant total volume fraction fT and measured the dynamics of the large particles as a function of the volume fraction of large particles. The dynamics of large particles became slower as the volume fraction of large particles r=fL/fT was decreased or the confinement thickness was decreased, indicating increasingly solid-like behavior. Second, we investigated the effects of variation in particle size dispersity r on the rheology and microstructure of mixtures of polymer and bidispersed colloids. Significant changes in rheology and microstructure were observed only at high volume fractions of large particles. By contrast, dense suspensions fT = 0.40 were strong gels at all concentration of large particles and exhibited only modest rheological and microstructural changes. Finally, we investigated the effects of variation in interparticle attractions on the microchannel flow of colloid-polymer mixtures. In suspensions with weak interparticle attractions, the number density of particles increased downstream in the channel due to shear-induced migration and consolidation by compression. In suspensions with stronger interparticle attractions, an interconnected network of particles suppressed these mechanisms and prevented the increase in density downstream. Together, our results indicate that the confined structure, dynamics, and flow properties of attractive colloidal suspensions can be controllably tuned from fluid-like to solid-like by varying the interparticle attractions and the particle size dispersity.
Download or read book Colloidal Suspension Rheology written by Jan Mewis and published by Cambridge University Press. This book was released on 2012 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented in an accessible and introductory manner, this is the first book devoted to the comprehensive study of colloidal suspensions.
Download or read book Theory and Applications of Colloidal Suspension Rheology written by Norman J. Wagner and published by Cambridge University Press. This book was released on 2021-04-15 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essential text on the practical application and theory of colloidal suspension rheology, written by an international coalition of experts.
Download or read book The Flow Properties of Colloidal Suspensions written by Bruce Andrew Firth and published by . This book was released on 1975 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Rheology written by and published by . This book was released on 2005 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dense Colloidal Suspensions in Microchannel Flow written by Philipp Kanehl and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colloids and the Depletion Interaction written by Henk N.W. Lekkerkerker and published by Springer Science & Business Media. This book was released on 2011-05-12 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloids are submicron particles that are ubiquitous in nature (milk, clay, blood) and industrial products (paints, drilling fluids, food). In recent decades it has become clear that adding depletants such as polymers or small colloids to colloidal dispersions allows one to tune the interactions between the colloids and in this way control the stability, structure and rheological properties of colloidal dispersions. This book offers a concise introduction to the fundamentals of depletion effects and their influence on the phase behavior of colloidal dispersions. Throughout the book, conceptual explanations are accompanied by experimental and computer simulation results. From the review by Kurt Binder: "They have succeeded in writing a monograph that is a very well balanced compromise between a very pedagogic introduction, suitable for students and other newcomers, and reviews of the advanced research trends in the field. Thus each chapter contains many and up to date references, but in the initial sections of the chapters, there are suggested exercises which will help the interested reader to recapitulate the main points of the treatment and to deepen his understanding of the subject. Only elementary knowledge of statistical thermodynamics is needed as a background for understanding the derivations presented in this book; thus this text is suitable also for advanced teaching purposes, useful of courses which deal with the physics for soft condensed matter. There does not yet exist any other book with a similar scope..... The readability of this book is furthermore enhanced by a list of symbols, and index of keywords, and last not least by a large number of figures, including many pedagogic sketches which were specifically prepared for this book. Thus, this book promises to be very useful for students and related applied sciences alike." Eur. Phys. J. E (2015) 38: 73
Download or read book Phase Behavior and Effective Interactions in Colloidal Suspensions written by and published by Cuvillier Verlag. This book was released on 2007-04-25 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloidal suspensions describe particles with size from typically a few nanometers to a few microns which are dispersed in a medium. In physics, in chemistry, and in biology colloids play an important role and the study of colloidal systems underwent a recent renaissance. This is based on the development of experimental techniques, the availability of extensive computer simulations and well-developed theoretical approaches. From a technological point of view, the relevance of micro- and nanostructured materials and the presence of colloids in nature and everyday life motivates study of this rich field. In this thesis the phase behavior and the effective interactions of colloidal suspensions in bulk, in contact with surfaces, and in confined geometry are studied. For mixtures of particles with hard-core interactions the model introduced by Asakura, Oosawa and Vrij provides an appropriate starting-point. Based on that model the free-volume theory and the density functional theory are employed. In experimental systems one faces particles with properties such as the size or the shape which are described by a distribution. To capture that issue a generalized approach based on free-volume theory for treating mixtures of colloids and a polydisperse depletion agent is presented. Within that approach it is possible to treat size and morphology polydispersity. A depletion agent with a bimodal distribution possessing two length scales can be studied. Though the Asakura-Oosawa-Vrij model describes a simple fluid - a mixture of hard spheres and ideal polymer - the phenomenology is rather rich: in contact with a wall one finds layering and wetting effects and in confined geometry of a narrow pore one finds capillary condensation. The competition between both effects manifests itself in thermodynamic properties like the excess colloid adsorption and the solvation force between the two confining walls. Solvent phase separation complicates the evaluation of interparticle interactions between the solute particles. We address this question for the wall-colloid and the colloid-colloid geometry. For a non-spherical particle the effect of curvature on thermodynamic quantities is studied.
Download or read book Capillary Flow of Dense Colloidal Suspensions written by Lucio Isa and published by . This book was released on 2008 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this thesis is to study the flow of dense colloidal suspensions into micronsized capillaries at the particle level. Understanding the flow of complex fluids in terms of their constituents (colloids, polymers, or surfactants) poses deep fundamental challenges, and has wide applications in many industrial processes. Through the use of a novel experimental procedure we find results contrasting with the predicted bulk rheological behaviour of dense colloidal systems and propose an alternative approach based on the analogy with granular systems. Quantitative predictions which successfully explain the data are obtained. In order to obtain quantitative information on the dynamics of the system, we image the flow using a fast confocal microscope and identify the trajectories of each particle. Due to the nature of the flow, conventional techniques for locating and tracking the particles fail to yield satisfactory results. To overcome this limitation, we have developed a novel technique which allows us to successfully track the particles in strongly non-uniform flow fields (published, 2006). We focus our attention on three main aspects of the flow: concentration gradients, velocity profiles and time behaviour. We initially discuss the occurrence of concentration gradients along the flow direction and relate them to the local flow profiles. We observe high density regions where the velocity is uniform across the channel (complete plugs) and lower density regions where shear is present. The observed concentration profiles can be qualitatively explained by considering the relative ow between the solvent and the suspended particles. The flow profiles in the presence of shear consist of a plug in the centre while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behaviour. However, the observed scaling of the velocity profiles with the flow rate strongly contrasts yield-stress fluid predictions. Instead, the velocity profiles can be captured by a theory of stress fluctuations originally developed for chute flow of dry granular media (published ,2007). We extend the model to our case and discuss it as a function of a series of parameters (boundary conditions, volume fraction, channel size, etc.) highlighting differences and similarities with granular media. Finally we discuss the time behaviour of complete plug flows relating it to the microscopic dynamics of the particles. At variance with dilute systems, dense systems exhibit velocity fluctuations when driven into channels by a constant pressure difference. We find that there exists a threshold value of the flow rate below which oscillations in the velocity are absent and above which their frequency scales as a power law of the flow rate. Despite quantitative predictions on this issue that are still missing, we present a microscopic description of the phenomenon highlighting the interplay between the particles and the solvent.
Download or read book Solid Liquid Two Phase Flow written by Sümer M. Peker and published by Elsevier. This book was released on 2011-04-18 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an undertaking of a pioneering work of uniting three vast fields of interfacial phenomena, rheology and fluid mechanics within the framework of solid-liquid two phase flow. No wonder, much finer books will be written in the future as the visionary aims of many nations in combining molecular chemistry, biology, transport and interfacial phenomena for the fundamental understanding of processes and capabilities of new materials will be achieved. Solid-liquid systems where solid particles with a wide range of physical properties, sizes ranging from nano- to macro- scale and concentrations varying from very dilute to highly concentrated, are suspended in liquids of different rheological behavior flowing in various regimes are taken up in this book. Interactions among solid particles in molecular scale are extended to aggregations in the macro scale and related to settling, flow and rheological behavior of the suspensions in a coherent, sequential manner. The classical concept of solid particles is extended to include nanoparticles, colloids, microorganisms and cellular materials. The flow of these systems is investigated under pressure, electrical, magnetic and chemical driving forces in channels ranging from macro-scale pipes to micro channels. Complementary separation and mixing processes are also taken under consideration with micro- and macro-scale counterparts.- Up-to-date including emerging technologies- Coherent, sequential approach- Wide scope: microorganisms, nanoparticles, polymer solutions, minerals, wastewater sludge, etc- All flow conditions, settling and non-settling particles, non-Newtonian flow, etc- Processes accompanying conveying in channels, such as sedimentation, separation, mixing
Download or read book Product Design and Engineering written by Ulrich Bröckel and published by John Wiley & Sons. This book was released on 2013-08-02 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the whole value chain - from product requirements and properties via process technologies and equipment to real-world applications - this reference represents a comprehensive overview of the topic. The editors and majority of the authors are members of the European Federation of Chemical Engineering, with backgrounds from academia as well as industry. Therefore, this multifaceted area is highlighted from different angles: essential physico-chemical background, latest measurement and prediction techniques, and numerous applications from cosmetic up to food industry. Recommended reading for process, pharma and chemical engineers, chemists in industry, and those working in the pharmaceutical, food, cosmetics, dyes and pigments industries.
Download or read book The Rheology of Attractive Suspensions written by Derek Eusean Huang and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex fluids form a broad class of materials, examples of which include foodstuffs, personal care products, biological fluids, industrial compounds, and geological materials. Detailed knowledge of their flow behavior is therefore key to understanding and predicting natural phenomena or developing new materials. In the past century, major advances in both experimental and theoretical methods have enabled greater understanding of the connection between the microscopic physical structure of complex fluids and their material response. Traditional rheology involves imposing deformation on a macroscopic sample of fluid and measuring the stress response. However, an increasing need to interrogate microscopically-small fluid samples, and a heightened interest in the colloid-level physics of biology, have motivated the development of techniques to interrogate microliter-size samples and resolve micron-length heterogeneities. One of these experimental techniques is active microrheology, where a microscopically small probe particle is driven through the material of interest. Constitutive relations between the force required to drive the probe and the speed with which it moves allow one to infer the effective viscosity of the material, and more recent expansions of the theory of active microrheology allow the direct measurement of suspension stress by monitoring the mean and fluctuating motion of the probe. Theoretical models that connect probe motion to material and flow properties have enjoyed great expansion in the last decade for the study of complex fluids of particles interacting hydrodynamically, or with repulsive forces. However, many systems of interest, including biological cells, comprise colloidal suspensions that experience attractive forces not previously represented in theoretical models. This work presents a theoretical study of the impact of attractive forces on the microstructure, microviscosity, and nonequilibrium osmotic pressure of colloidal suspensions as measured by active microrheology. In active microrheology, the probe distorts the surrounding microstructure from its equilibrium configuration. The degree of this distortion is set by the strength of external forcing relative to entropic restoring forces; interparticle attractions and repulsions also influence this evolution. Although the effects of repulsions are well-studied in prior literature, a theoretical understanding of attraction-induced effects on nonequilibrium rheology is lacking. To examine how this interplay between different microscopic forces influences rheology, we formulate a Smoluchowski equation governing pair configuration as it evolves with flow strength, interparticle attractions, and hydrodynamic interactions. We determine its solution and compute microviscosity and nonequilibrium osmotic pressure from the structure via statistical mechanics. When the probe is subject to external forcing, attractions speed upstream probe-bath encounters and slow downstream detachment, transferring particle density downstream. This sets both the strength and direction of dipolar disturbance under weak forcing and the boundary-layer and wake structure under strong forcing. These attraction-induced structural changes affect rheology: both attraction-thinning and attraction-thickening are observed in the weak-forcing limit, while sufficiently strong forcing breaks attractive bonds and leads to flow-thinning or, in the presence of hydrodynamic interactions, flow-thickening. We find that the equilibrium osmotic pressure, described by the second virial coefficient B2, accurately predicts structural and rheological behavior in the weak-forcing limit regardless of specific attractive potential, but that the secondary length scale that arises under strong forcing precludes potential-agnostic observations far from equilibrium. The structural transitions and non-monotonic rheology in active microrheology show that tuning surface stickiness can either enhance or hinder probe motion and provide a means by which proteins or other macromolecules may change their surface chemistry to alter the viscosity of the surrounding medium, either speeding or slowing their own motion. Attractive forces are known to reduce the equilibrium osmotic pressure; as the second virial coefficient becomes more strongly negative, it is possible for phase separation to occur. This behavior changes away from equilibrium, where we find that the flow-induced nonequilibrium osmotic pressure reaches a minimum at a critical value of B2 before increasing with attraction strength. Hydrodynamic interactions suppress the nonequilibrium osmotic pressure and, at certain attraction strengths, can give rise to a flow-induced reduction in osmotic pressure below its equilibrium value. This denotes a flow-induced destabilization of attractive suspensions that may lead to phase separation in more concentrated systems, suggesting that self-assembly of active particles in biological suspensions may be driven by both attractive forces and hydrodynamic interactions
Download or read book Hydrodynamic Effects on Active Colloidal Suspensions written by Eloy Navarro Argemí and published by . This book was released on 2019 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis is studying hydrodynamic effects on active colloidal suspensions. Hydrodynamic interaction is propagated through the fluid in which the colloids displace due to the flow they create during their motion. It can lead to the emergence of collective phenomena, such as the self-assembly of more complex structures. Hydrodynamic interactions are not the only present in the system, since other forces may be acting between colloids, or there can be external fields acting on them such as gravity. We present our study for two different systems: magnetic colloids and Janus particles. When applying a circular magnetic field, we can induce a rotation to a particle possessing a magnetic moment. Due to the coupling of the flow with the one created by surrounding particles and with system interfaces, a rotor will eventually self-propel. Two magnetic moments interact with each other through the magnetic dipole-dipole force, which tends to align them into arrays. We study how the balance between hydrodynamic, magnetic and gravitational forces determines the morphology of the structures magnetic colloids can form. Janus particles have two faces with different chemical properties, thus the interaction between them depends on their relative orientation. We study the morphology and order of the structures that can emerge for these particles as a function of the intensity, sign and reach of the interaction between them, as well as the type of flow they create when self-propelling. Methodologically, we have combined the use of far-field theory to draw analytical expressions that have given us qualitative insight on the results we could expect with high-performance computing simulations which have allowed us to extend our study to bigger systems.
Download or read book Soft and Fragile Matter written by Michael E. Cates and published by CRC Press. This book was released on 2000-01-01 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering colloids, polymers, surfactant phases, emulsions, and granular media, Soft and Fragile Matter: Nonequilibrium Dynamics, Metastability and Flow (PBK) provides self-contained and pedagogical coverage of the rapidly advancing field of systems driven out of equilibrium, with a strong emphasis on unifying conceptual principles rather than material-specific details. Written by internationally recognized experts, the book contains introductions at the level of a graduate course in soft condensed matter and statistical physics to the following areas: experimental techniques, polymers, rheology, colloids, computer simulation, surfactants, phase separation kinetics, driven systems, structural glasses, slow dynamics, and granular materials. These topics lead to a range of exciting applications at the forefront of current research, including microplasticity of emulsions, sequence design of copolymers, branched polymer dynamics, nucleation kinetics in colloids, multiscale modeling, flow-induced surfactant textures, fluid demixing under shear, two-time correlation functions, chaotic sedimentation dynamics, and sound propagation in powders. Balancing theory, simulation, and experiment, this broadly-based, pedagogical account of a rapidly developing field is an excellent compendium for graduate students and researchers in condensed matter physics, materials science, and physical chemistry.
Download or read book Advances in Chemical Physics Volume 140 written by Stuart A. Rice and published by John Wiley & Sons. This book was released on 2008-06-23 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series, Advances in Chemical Physics, provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline.
Download or read book Rheology written by Frederick R. Eirich and published by Academic Press. This book was released on 2014-05-12 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rheology: Theory and Applications, Volume 5 focuses on overtly fluid behavior of polymers, including the theory of large deformations, thermoelastic effects, elastic phenomena observed during the extrusion of polymeric melts, and theories of the structure of liquids and glasses. The selection first elaborates on the application of large deformation theory to the thermomechanical behavior of rubberlike polymers and unstable flow of molten polymers. Discussions focus on the mechanism proposed for unstable flow, ripple and associated effects, direct observation of waviness phenomena, empirical behavior of porous, unfilled, and filled rubberlike polymers, and problems connected with the interpretation of mechanical response parameters. The text then examines elasticity effects in polymer extrusion and strength and extensibility of elastomers. The publication takes a look at free volume and polymer rheology and studies of the deformation of crystalline polymers. Topics include the contribution of the two orientation processes to the birefringence, deformation of superstructure, rate of orientation of crystalline regions, free volume and physical state, glass transition and free volume, and reappraisal of time-temperature superposition. The manuscript also elaborates on the deformation and dissipative processes in high polymeric solids and the thermodynamics of deformation. The selection is a vital source of data for researchers interested in the theories and applications of rheology.
