Physical characteristics of emulsions

An assessment of emulsion stability involves the determination of the time variation of some emulsion property such as those described in the earlier section Physical Characteristics of Emulsions . The classical methods are well described in reference 9. Some newer approaches include the use of pulse nuclear magnetic resonance spectroscopy or differential scanning calorimetry (52). 

Approximate number of theoretical stages for extraction and stripping The necessity or desirability of a scrub stage between extraction and stripping The physical characteristics of the system i.e., dispersion requirements and settling rates, emulsion tendencies, viscosity, etc. 

It is anticipated, and in fact is true, that the physical properties and performance characteristics of emulsion polymers prepared by routes I and IV are different. The question here is whether it is possible by characterization techniques to distinguish polymers made by different routes and, more subtly, by the same nominal route but with some process aberration such as a feed upset. In order to determine the feasibility of such an approach, an emulsion copolymer system was selected the copolymer of styrene and ethyl acrylate. 

In the last year a new formulation of aminocarb has appeared on the insecticide market. It is finely ground aminocarb suspended in an oil and it has the advantage that it can be tank mixed to give either an oil or a water suspension. Studies (10) show that, like the oil solution, this product has a half life in the same range (3.2 to 6.0 days). There was an indication of a variation in the initial rate of loss due to the physical characteristics of the water emulsion spray (in a series of repeat studies the evaporation rate was not constant). The presence of the emulsifier inhibited evaporation resulting in a higher initial foliar deposit than with the oil base spray. The occurence of the lower rate of deposit of the oil spray can be attributed to the particular oil used in the Canadian budworm sprays. To meet the concerns of the health authorities the standard No. 2 and No. 4 fuel oils which had been used are now prohibited. The accepted product, known as Insecticide Diluent 585 is volatile with an evaporation rate approaching that of water. 

The interfacial films formed by different crude oils have different characteristics. The physical characteristics of the films are a function of the crude-oil type and gas content, the composition and pH of water, the temperature, the presence of nonionic polar molecules in the water, the extent to which the adsorbed film is compressed, and the contact time allowed for adsorption and concentration of polar molecules in the oil phase 14, 22,23). The rheological properties of the adsorbed emulsifier film have an important effect on the stability of emulsions. 

Changing the physical characteristics of an emulsion by the addition of diluents or water. 

The answer is a. (Murray, pp 627-661. Scriver, pp 3897-3964. Sack, pp 121-138. Wilson, pp 287-320.) Vitamins A, D, E, and K are all fat-soluble. The physical characteristics of fat-soluble vitamins derive from the hydrophobic nature of the aliphatic chains composing them. The other vitamins listed are water-soluble, efficiently administered orally, and rapidly absorbed from the intestine. Fat-soluble vitamins must be administered intramuscularly or as oral emulsions (mixtures of oil and water). In intestinal disorders such as chronic diarrhea or malabsorption due to deficient digestive enzymes, fat-soluble vitamins are poorly absorbed and can become deficient. Supplementation of fat-soluble vitamins is thus routine in disorders like cystic fibrosis (219700), a cause of respiratory and intestinal disease that is the likely diagnosis in this child. 

Microemulsions are thermodynamically stable phases, which can be represented by clear areas in equilibrium phase diagrams. Nanoemulsions are really small emulsions, with the main characteristics of emulsions they are not thermodynamically stable and the way they are prepared has a great impact on their physical stability. The only difference with common emulsions is their very small droplet size, which ranges from 10 to 500 nm. Accordingly, nanoemulsions may look bluish, due to light diffusion (brown/yellow by transmission), just like microemulsions close to a critical point. 

In the petroleum industry, not all W/O emulsions are the same. The nature of emulsions formed in crude oil often depends on many factors the geologic source and the engineering processes utilized in the crude oil recovery, the chemical and physical characteristics of the crudes and their thermal history, the type of mixing and energy introduced,... 

Finally, creaming is a process which is related to flocculation in that it occurs without the loss of individual drop identities (Fig. 11.2d). Creaming will occur over time with almost all emulsion systems in which there is a difference in the density of the two phases. The rate of creaming will be dependent on the physical characteristics of the system, especially the viscosity of the continuous phase. It does not necessarily represent a change in the dispersed state of the system, however, and can often be reversed with minimal energy input. If the dispersed phase happens to be the more dense of the two phases, the separation process is termed sedimentation. 

For a more in-depth discussion of the physical and chemical characteristics of emulsion explosives, see Blasters Handbook, 77-84 and Bampfield, Howard A. and John Cooper. 1988. Emulsion explosives. Chapter 7 in Encyclopedia of Emulsion Technology. New York and Basel Marcel Dekker. Mixtures consisting of a water-based explosive material matrix or an oxidizer matrix, and ammonium nitrate or ANFO, may also be referred to as blended explosives, blends, or heavy ANFO. 

Riess and co-workers [161,168] have synthesized a large number of fluoroalkylated amphiphiles. Their versatile modular design allowed a stepwise modification of the surfactant size and charge, as well as the hydrophilic, lipophilic, and fluorophilic character. The nature of the head, the number of tails (identical or different), the spacers, the connecting units, and the sites were altered in order to manipulate the physical and biological characteristics of emulsions, vesicles, and other colloidal systems. 

Treating processes and equipment should not be selected until the physical characteristics of the oil and water have been determined and a study of the effect of available chemicals on the emulsion has been made. 

The HLB system has made it possible to organize a great deal of rather messy information and to plan fairly efficient systematic approaches to the optimiza-tion of emulsion preparation. If pursued too far, however, the system tends to lose itself in complexities [74]. It is not surprising that HLB numbers are not really additive their effective value depends on what particular oil phase is involved and the emulsion depends on volume fraction. Finally, the host of physical characteristics needed to describe an emulsion cannot be encapsulated by a single HLB number (note Ref. 75). 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

The completion stage is identified by the fact that all the monomer has diffused into the growing polymer particles (disappearance of the monomer droplet) and reaction rate drops off precipitously. Because the free radicals that now initiate polymerization in the monomer-swollen latex particle can more readily attack unsaturation of polymer chains, the onset of gel is also characteristic of this third stage. To maintain desirable physical properties of the polymer formed, emulsion SBR is usually terminated just before or at the onset of this stage. 

This paper presents the physical mechanism and the structure of a comprehensive dynamic Emulsion Polymerization Model (EPM). EPM combines the theory of coagulative nucleation of homogeneously nucleated precursors with detailed species material and energy balances to calculate the time evolution of the concentration, size, and colloidal characteristics of latex particles, the monomer conversions, the copolymer composition, and molecular weight in an emulsion system. The capabilities of EPM are demonstrated by comparisons of its predictions with experimental data from the literature covering styrene and styrene/methyl methacrylate polymerizations. EPM can successfully simulate continuous and batch reactors over a wide range of initiator and added surfactant concentrations. 

Hence, from the previously described light-scattering study of caseinate self-assembly in solution, we can postulate that heating/cooling not only alters the nature and strength of the physical (hydrophobic) interactions between emulsion droplets covered by caseinate. It most likely also transforms the nanoscale structural characteristics of the protein network in the bulk and at the interface, thereby affecting the viscoelastic and microstructural properties of the emulsions. 

Following preliminary hypochlorite treatments, a coherent process path was identified and implemented. Corn starch was oxidized with 6.4% (w/w) hypochlorite for two hours and given a combined base-heat gelatinization process (Method A). This base material exhibited excellent physical characteristics (i.e., stable emulsion with 20% db lemon oil incorporation into an aqueous dispersion, low lemon oil vapor phase flux (low headspace content), lack of inherent flavor and aroma) and when finally tested for spray dried lemon oil (20% db) retention efficiency in a lab-scale mini-dryer, the viability of this polymer was ascertained. Nearly 70% of the added lemon oil was retained following the drying of this DE 1.45 starch, a measure of functionality matched only by gum arabic (34). 

This chapter describes some methods to study physical characteristics and ingredient interactions in whippable dairy-based emulsions. The story of whippable emulsions begins with natural dairy cream. From this starting point a range of dairy-type whippable emulsions has been developed over the years. 

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