Emulsions and Emulsion Stability


Book Description

Emulsions and Emulsion Stability, Second Edition provides comprehensive coverage of both theoretical and practical aspects of emulsions. The book presents fundamental concepts and processes in emulsified systems, such as flocculation, coalescence, stability, precipitation, deposition, and the evolution of droplet size distribution. The bo




Emulsion Formation and Stability


Book Description

The importance of emulsification techniques, their use in the production of nanoparticles for biomedical applications as well as application of rheological techniques for studying the interaction between the emulsion droplets is gathered in this reference work. Written by some of the top scientists within their respective fields, this book covers such topics as emulsions, nano-emulsions, nano-dispersions and novel techniques for their investigation. It also considers the fundamental approach in areas such as controlled release, drug delivery and various applications of nanotechnology.




Emulsions: Structure, Stability and Interactions


Book Description

Emulsions: Structure, Stability and Interactions is the perfect handbook for scientists looking to obtain up-to-date knowledge about the fundamentals of emulsion science, and those looking to familiarize themselves with the subject in greater detail. As a 'stand-alone' source of information, it is also ideal for solving the practical issues encountered daily in the field of emulsion science. While each chapter presents a concise review on a specific topic, the book offers a consistent presentation of the important physical concepts relevant to emulsions. Some of the topics covered include statistical mechanics of fluid interfaces, the structure of fluid interfaces determined by neutron scattering, hydrodynamic interactions and stability of emulsion films, theory of emulsion flocculation, coalescence kinetics of Brownian emulsions, and Brownian dynamics simulation of emulsion stability. - Full and comprehensive presentations - Rigorous approach to each topic, providing in-depth information - Acts as a 'stand-alone' source of information




Emulsions


Book Description

Chapter 1 General Introduction Definition of emulsions and the role of the emulsifier. Classification based on the nature of the emulsifier. Classification based on the structure of the system. General instability problems with emulsions : creaming/sedimentation, flocculation, Ostwald ripening, coalescence and phase inversion. Importance of emulsions in various industrial applications. Chapter 2 Thermodynamics of Emulsion Formation and Breakdown Application of the second law of thermodynamics for emulsion formation : Balance of energy and entropy and non-spontaneous formation of emulsions. Breakdown of the emulsion by flocculation and coalescence in the absence of an emulsifier. Role of the emulsifier in preventing flocculation and coalescence by creating an energy barrier resulting from the repulsive energies between the droplets. Chapter 3 Interaction Forces between Emulsion Droplets Van der Waals attraction and its dependence on droplet size, Hamaker constant and separation distance between the droplets. Electrostatic repulsion resulting from the presence of electrical double layers and its dependence on surface (or zeta) potential and electrolyte concentration and valency. Combination of the van der Waals attraction with double layer repulsion and the theory of colloid stability. Steric repulsion resulting from the presence of adsorbed non-ionic surfactants and polymers. Combination of van der Waals attraction with steric repulsion and the theory of steric stabilisation. Chapter 4 Adsorption of Surfactants at the Oil/Water Interface Thermodynamic analysis of surfactant adsorption and the Gibbs adsorption isotherm. Calculation of the amount of surfactant adsorption and area per surfactant molecule at the interface. Experimental techniques for measuring the interfacial tension. Chapter 5 Mechanism of Emulsification and the Role of the Emulsifier Description of the factors responsible for droplet deformation and its break-up. Role of surfactant in preventing coalescence during emulsification. Definition of the Gibbs dilational elasticity and the Marangoni effect in preventing coalescence. Chapter 6 Methods of Emulsification Pipe flow, static mixers and high speed stirrers (rotor-stator mixer). Laminar and turbulent flow. Membrane emulsification. High pressure homogenisers and ultrasonic methods. Chapter 7 Selection of Emulsifiers The hydrophilic-lipophilic-balance (HLB) and its application in surfactant selection. Calculation of HLB numbers and the effect of the nature of the oil phase. The phase inversion temperature (PIT) method for emulsifier selection. The cohesive energy ratio method for emulsifier selection. Chapter 8 Creaming/Sedimentation of Emulsions and its prevention Driving force for creaming/sedimentation: effect of gravity, droplet size and density difference between the oil and continuous phase. Calculation of the rate of creaming/sedimentation in dilute emulsions. Influence of increase of the volume fraction of the disperse phase on the rate of creaming/sedimentation. Reduction of creaming/sedimentation: Balance of the density of the two phases, reduction of droplet size and effect of addition of ''thickeners'. Chapter 9 Flocculation of Emulsions and its Prevention Factors affecting flocculation. Calculation of fast and slow flocculation rate. Definition of stability ratio and its dependence on electrolyte concentration and valency. Definition of the critical coagulation concentration and its dependence on electrolyte valency. Reduction of flocculation by enhancing the repulsive forces. Chapter 10 Ostwald Ripening and its Reduction Factors responsible for Ostwald ripening : difference in solubility between small and large droplets and the Kelvin equation. Calculation of the rate of Ostwald ripening. Reduction of Ostwald ripening by incorporation of a small amount of highly insoluble oil. Reduction of Ostwald ripening by the use of strongly adsorbed polymeric surfactant and enhancement of the Gibbs elasticity. Chapter 11 Emulsion Coalescence and its Prevention Driving force for emulsion coalescence : Thinning and disruption of the liquid film between the droplets. The concept of disjoining pressure for prevention of coalescence. Methods for reduction or elimination of coalescence : Use of mixed surfactant films, use of lamellar liquid crystalline phases and use of polymeric surfactants. Chapter 12 Phase Inversion and its Prevention Distinction between catastrophic and transient phase inversion. Influence of the disperse volume fraction and surfactant HLB number. Explanation of the factors responsible for phase inversion. Chapter 13 Characterisation of Emulsions Measurement of droplet size distribution : Optical microscopy and image analysis. Phase contrast and polarising microscopyDiffraction methods. Confocal laser microscopy. Back scattering methods Chapter 14 Industrial Application of Emulsions 14.1 Application in Pharmacy 14.2 Application in Cosmetics 14.3 Application in Agrochemicals 14.4 Application in Paints 14.5 Application in the Oil Industry




Emulsions


Book Description

Proceedings of the NATO Advanced Research Workshop, Bergen, Norway, June 24-25, 1991




Modern Aspects of Emulsion Science


Book Description

Emulsions occur either as end products or during the processing of products in a huge range of areas including the food, agrochemical, pharmaceutical, paint and oil industries. Despite over one hundred years of research in the subject, however, a quantitative understanding of emulsions has been lacking. Modern Aspects of Emulsion Science presents a comprehensive description of both the scientific principles in the field and the very latest advances in research in this important area of surface and colloid science. Topics covered include emulsion formation, type, stability (creaming, flocculation, ripening, coalescence), monodisperse and gel emulsions, and applications. Emphasis has been placed on relating the chemistry of the surfactant or protein adsorbed at the oil-water interface to the principles of the physics involved in the bulk emulsion property. The book has been written by a collection of the world's leading experts in the field, and covers both experimental and theoretical approaches. Modern Aspects of Emulsion Science fills a real gap in the market, being the only book of its kind in print. As such it will prove essential reading for graduates and researchers in this subject, in both academia and industry.




Emulsion Science


Book Description

Emulsions occur either as end products or during the processing of products in a huge range of areas including the food, agrochemical, pharmaceuticals, paints and oil industries. As end products, emulsions allow to avoid organic solvent in processing hydrophobic coatings. Emulsion technology is a suitable approach to vehicle viscous phases. It is also a remarkable mean of targeting actives or capturing specific species. The range of applications of emulsions progresses and their manufacturing becomes more and more sophisticated. Besides this broad domain of technological interest, emulsions are raising a variety of fundamental questions at the frontier between physic and chem istry. Indeed, as a class of soft colloidal materials, emulsions science is linked to various aspects of these disciplines: phase transitions, surface forces and wetting, metastability and hydrodynamic instabilities, mechanical properties and flow. The aim of this book is to review the main important concepts governing emulsion science. In Chapter 2, repulsive interactions between liquid films are discussed as well as adhesive interaction related to wetting. In Chap ter 3, consequences of weak and strong attractions are presented, related to the well accepted liquid solid transition analogy. In Chapter 4, the basics of both bulk compressibility and shear elasticity are presented, the role of disorder being the most important aspect of the elastic behavior of these soft systems. In Chapter 5 the central question of the emulsion lifetime related to metastability is discussed.




Emulsion-based Systems for Delivery of Food Active Compounds


Book Description

A comprehensive text that offers a review of the delivery of food active compounds through emulsion-based systems Emulsion-based Systems for Delivery of Food Active Compounds is a comprehensive recourse that reviews the principles of emulsion-based systems formation, examines their characterization and explores their effective application as carriers for delivery of food active ingredients. The text also includes information on emulsion-based systems in regards to digestibility and health and safety challenges for use in food systems. Each chapter reviews specific emulsion-based systems (Pickering, multiple, multilayered, solid lipid nanoparticles, nanostructured lipid carriers and more) and explains their application for delivery of food active compounds used in food systems. In addition, the authors – noted experts in the field – review the biological fate, bioavailability and the health and safety challenges of using emulsion-based systems as carriers for delivery of food active compounds in food systems. This important resource: Offers a comprehensive text that includes detailed coverage of emulsion-based systems for the delivery of food active compounds Presents the most recent development in emulsion-based systems that are among the most widely-used delivery systems developed to control the release of food active compounds Includes a guide for industrial applications for example food and drug delivery is a key concern for the food and pharmaceutical industries Emulsion-based Systems for Delivery of Food Active Compounds is designed for food scientists as well as those working in the food, nutraceutical and pharmaceutical and beverage industries. The text offers a comprehensive review of the essential elements of emulsion-based systems for delivery of food active compounds.




Foams and Emulsions


Book Description

A general and introductory survey of foams, emulsions and cellular materials. Foams and emulsions are illustrations of some fundamental concepts in statistical thermodynamics, rheology, elasticity and the physics and chemistry of divided media and interfaces. They also give rise to some of the most beautiful geometrical shapes and tilings, ordered or disordered. The chapters are grouped into sections having fairly loose boundaries. Each chapter is intelligible alone, but cross referencing means that the few concepts that may not be familiar to the reader can be found in other chapters in the book. Audience: Research students, researchers and teachers in physics, physical chemistry, materials science, mechanical engineering and geometry.




Emulsions, Microemulsions and Foams


Book Description

This book takes an interface science approach to describe and understand the behavior of the dispersions we call emulsions, microemulsions and foams. The one thing all these dispersions have in common is the presence of surface-active species (surfactants) adsorbed at the interfaces between the two fluid phases that make up the emulsions, microemulsions or foams. The interfacial layers formed by the surfactants control most of the properties of the dispersions. The book describes the properties of interfacial layers, thin films and bulk fluids used in the elaboration of the various dispersions and it explains how such properties relate to the dispersion properties of these soft matter systems: structure, rheology and stability. These dispersion properties are far from being fully understood, in particular foam and emulsion stability. In discussing the state of the art of the current knowledge, the author draws interesting parallels between emulsions, microemulsions and foams that enlighten the interpretation of previous observations and point to a deeper understanding of the behavior of these materials in the future.