Emulsion fundamental aspects

Isaacs, E.E. Chow, R.S. Practical Aspects of Emulsion Stability in Emulsions, Fundamentals and Applications in the Petroleum Industry, Schramm, L.L. (Ed.), American Chemical Society Washington, 1992, pp. 51-77. 

The difference between well-known SCF antisolvent techniques such as GAS, PCA, and SEDS usually can be attributed to the specific nozzle mixing (or dispersing) technique involved. Enhanced mass and heat transfer can also be achieved by using mechanical and ultrasonic mixers and ultrafast jet expansion techniques. There are new developments for particle formation by means of dispersed systems such as emulsions, micelles, colloids, and polymer matrixes. It should be emphasized that all these processes involve the same fundamental aspects of mass and heat transfer phenomena between an SCF and a subcritical phase. Clearly the ultimate goal of all SCF particle technologies is to achieve predictable, consistent, and economical production of fine pharmaceuticals or chemicals. This is possible only on the basis of comprehensive mechanistic understanding and well-developed scale-up principles. 

Liquid-liquid and solid-liquid dispersed systems are complicated forms from a physicochemical point of view, because of the presence of two phases. Their formulation therefore necessitates comprehension of fundamental aspects controlling the behavior of these systems. With this end in view, we begin this volume with theoretical considerations concerning pharmaceutical surfactants, formulation concepts, and emulsion properties, and the related know-how to attain them. As the text progresses, each chapter becomes more advanced and specific. Thermodynamic and kinetic aspects of suspension formulations, as well as... 

Working with emulsion systems is nothing new to people in the petroleum industry. Historically and economically, the most important problems in the oil industry have been in the area of breaking up o/w emulsions formed within reservoirs. However, the breaking and formation of emulsions plays a very important role in other technological applications in the oil industries. Because of their wide-ranging practical importance, it is necessary to discuss the fundamental aspects and methods of characterization of emulsions. 

Aerosols, like foams, emulsions, and dispersions, may be either advantageous or detrimental, depending on the situation. The previous discussion introduced some of the fundamental aspects of aerosol formation. Of equal or perhaps greater practical importance is the question of the suppression of aerosol formation, the destruction of unavoidable aerosols, or the controlled deposition of aerosols onto surfaces. Perhaps the best approach to solving such problems is through an understanding of some of the general principles involved in their stabilization and destruction. In that context, some of the mechanisms of destruction involved will be essentially the same as those for other colloidal systems flocculation and coalescence. 

The proceedings cover six major areas of research related to chemical flooding processes for enhanced oil recovery, namely, 1) Fundamental aspects of the oil displacement process, 2) Microstructure of surfactant systems, 3) Emulsion rheology and oil displacement mechanisms, 4) Wettability and oil displacement mechanisms, 5) Adsorption, clays and chemical loss mechanisms, and 6) Polymer rheology and surfactant-polymer interactions. This book also includes two invited review papers, namely, "Research on Enhanced Oil Recovery Past, Present and Future," and "Formation and Properties of Micelles and Microemulsions" by Professor J. J. Taber and Professor H. F. Eicke respectively. 

The main objective of this volume is to demonstrate the importance of the fundamental aspects of interfadal phenomena in various industrial applications. For this purpose 1 have chosen five different topics which are described in five parts. The first part deals with cosmetics and personal care formulations. Several cosmetic formulations can be identified lotions, hand creams (cosmetic emulsions), nanoemulsions, multiple emulsions, liposomes, shampoos and hair conditioners, sunscreens and color cosmetics. The formulation of these complex multiphase systems requires understanding the colloidal forces that eire responsible for their preparation, stabilization and application. The fundamental principles that are responsible for the formulation of the cosmetic formulations must be considered. 

In summary, there has been a tremendous effort devoted to the fundamental aspects of emulsion polymerization mechanisms, kinetics and processes since the early twentieth century. Representative review or journal articles concerning the conventional emulsion polymerization can be found in literature [20-25, 48-60]. The research areas related to both miniemulsion [42,61-64] and microemulsion [44-47, 65] polymerizations have received increasing interest recently. 

In this chapter, the characteristic properties of nano-emulsions and relevant applications have been described. A great deal of research effort in recent years has been focused toward the conditions required for nano-emulsion formation. Low interfacial tension values and the presence of lamellar liquid crystalline phases are among the factors that have been shown to be important for their formation. However, it has also been shown that the kinetics of the emulsification process plays a key role. Comprehensive knowledge of the fundamental aspects related to nano-emulsion formation and stability will allow improvement of established applications, such as those described in this chapter, and development of new ones. 

This book focuses on emulsions, foams, and suspensions their fundamentals and applications. The variety of systems represented or suggested by Tables 1.1 and 1.2 underscores the fact that the problems associated with colloids are usually interdisciplinary in nature and that a broad scientific base is required to understand them completely. A wealth of literature exists on the topic of colloidal dispersions, including a range of basic colloid reference texts [12-28], dictionaries [9-11,29], and treatises on the myriad of applied aspects, of which only a few are cited here [1-5,30-36], The widespread importance of emulsions, foams, and suspensions in particular, and scientific interest in their formation, stability and properties, have precipitated a wealth of specialized publications dedicated to each of emulsions [37-42], foams [43-47], and suspensions [48-51],... 

Although surface phenomena determine the fundamental properties of emulsions in terms of size distributions and stability, the bulk properties or bulk compositions are the yardsticks by which plant operators and process personnel measure process efficiency. Accurate determination of the oil, water, and solids (if present) is therefore one of the most important aspects of emulsion characterization. 

Another problem involves the classification of these metal-based heterogeneous systems into suspension, dispersion, and emulsion polymerizations similarly to conventional systems. This is due to not only a lack of detailed analysis of reaction mechanisms and particle sizes but also fundamental differences in several aspects such as the locus of initiation and the molecular weight of polymers in comparison with the conventional counterparts. The terms suspension and emulsion will be used in the following sections for simple classification but are not based on the strict definition for conventional free radical systems. 

Chapters 26—29 all discuss hydrodynamic aspects of emulsified systems. The contribution by Danov, Kralchevsky, and Ivanov presents a very fundamental and thorough survey of different phenomena in emulsions related to dynamic and hydrodynamic motions, such as the dynamics of surfactant adsorption mono-layers, which include the Gibbs surface elasticity, and characteristic time of adsorption, mechanisms of droplet-droplet coalescence, hydrodynamic interactions and drop coalescence, interpretation of the Bancroft rule with regard to droplet symmetry, and, finally, kinetics of... 

However, as we discuss later in this chapter, the equilibrium thermodynamic considerations can address only a part of the issues encountered in polymer-polymer, polymer-filler, and polymer-polymer-filler blends. In these cases, high viscosity of polymers limits attaining the thermodynamic equilibrium. Hence, kinetic factors, such as mixing rate, strain type, and strain history, become dominant, although the information from thermodynamics is still useful. Here, we only discuss certain aspects of filled emulsions. A more detailed description of all relevant phenomena is beyond the scope of this chapter. Interested readers are referred to fundamental studies reported elsewhere [10]. 

This reference book or textbook is devoted to updating the current development of knowledge of emulsion polymerization. The author also endeavors to incorporate balanced fundamental and applied aspects of various emulsion polymerization processes into this work. This volume is particularly designed for research workers (such as chemists, chemical engineers, materials scientists, and physicists), technical service personnel, professors, and upper-level undergraduate and graduate students. It serves as an introduction to this important field and as a bridge to the more spedalist-oriented books, which are available in the marketplace. 

The measurement of forces between surfaces at small separation is of great importance in gaining a fundamental understanding of the complex behaviour of colloidal systems. Interactions of solid surfaces (coated or uncoated) across a fluid medium have been made through development of both the surface forces apparatus (SFA) and the atomic force microscope. Interactions between liquid surfaces are generally discussed in terms of the variation of the disjoining pressure with surface separation, and the majority of studies relate to foam (i.e. vapour-liquid-vapour) Investigations of various aspects of emulsion (i.e. liquid-liquid-... 

Proteins are the most important foams and emulsifiers used in food technology since they fulfill both a practical and a nutritional aspect. Often, surfactants and polymers are added to the system to improve its stability. Food dispersions can be very complex, such as solid foams, in which the system is solidified after heating, such as cakes or bread, or after freezing, such as ice creams. Furthermore, ice creams are even more complex since they consist of foam made from an emulsion. However, this chapter is devoted to the study of the structure of foams and emulsions on the basis of their fundamental physicochemical properties. Hence, we will focus on liquid foams and emulsions. 

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