Emulsions dilute

Fig. 12.5. Effect of length of autoradiographic exposure on grain count. BHK21/C13 cells labelled with [3H]uridine were covered with Ilford L4 emulsion (diluted with an equal volume of water) dried in a horizontal position and exposed in air at room temperature for the indicated times. (Courtesy of K. Shaw and Dr. J.D. Pitts.)...

A 10-year-old boy who had sustained 25% first-degree and second-degree burns and was treated with frequent daily applications of a 3% hexachlorophene emulsion (diluted and undiluted) developed a fatal encephalopathy (7). 

We first tried to evaluate the effect of increasing oil viscosity in an otherwise equivalent emulsion environment. We checked this by using standard PDMS oils of 1000, 5000, 60 000 and 125 000 cps in emulsion. These tests were conducted with emulsions diluted to 10% solids. 

Emulsion - Dilute 4 76 with 160 ppm hard water. Formulation SOL-001-01... 

The first effective synthetic herbicide was 2,4-D, discovered in the mid-1940s. The first formulations were emulsions diluted in water and applied by broadcast sprays. Initial application rates in the 1950s were up to 75-150 lb acre against some weeds. These applications were performed... 

The first step is to prepare the emulsion for microscopic observation. It has to be diluted and the operator must check that the dilution does not affect the emulsion. Dilution media are aqueous gelatine, acacia solution, glycerine, propylene glycol, and so forth. 

McNulty and Karel define a dimensionless parameter [F J/[F J which is always greater than 1.0 in their model and is a measure of the potential extent of release, defined as the potential extent of increase in aqueous concentration. The release potential is determined by the difference between [F ] and [F ]. Fig. 8.42 shows the influence of partition coefficient P and < j on the aqueous concentration of flavour immediately after emulsion dilution [F, ] and at equilibrium [F ] when /c = 2, and [F J = lOOppm. Uptake curves [Fwe]/[Fwd] < are obtained for the model when an emulsion initially containing no flavour is diluted with an aqueous phase containing an initial... 

Although totally protein-free hydrocoUoids could not be obtained, it is clear that these gums adsorb onto the oil interface and do not merely contribute to the viscosity of the continuous phase. Series of tests were conducted both on aqueous dispersions of hydrocolloids (heat treatment, dilution, pH change, addition of electrolytes, etc.) and on emulsions (dilution, heat treatment, addition of monomeric emulsifiers, etc.). From these tests it seems that the role of the protein, if any, is insignificant and not similar in any way to its role in gum arabic. 

Kodak NTB-2 autoradiographic emulsion diluted 1 1 with H O and stored in 10-ml aliquots in a light-tight box. When diluting emulsion, mix gently to avoid making bubbles. 

Uses Surfactant water repellent mfg. of release agents Properties Milky wh. emulsion dilutable with water sp.gr. 0.99 g/cm (20 C) pH 6.0-8.5 60% silicone... 

An emulsion may be defined as a mixture of particles of one liquid with some second liquid. The two common types of emulsions are oil-in-water (O/W) and water-in-oil (W/0), where the term oil is used to denote the water-insoluble fiuid. These two types are illustrated in Fig. XIV-1, where it is clear that the majority or outer phase is continuous, whereas the minority or inner phase is not. These two emulsion types are distinguished by their ability to disperse oil or water-soluble dyes, their dilution with oil or water, and their conductivity (O/W emulsions have much higher conductivity than do W/0 ones see Ref. 1 for reviews). 

Apart from chemical composition, an important variable in the description of emulsions is the volume fraction, outer phase. For spherical droplets, of radius a, the volume fraction is given by the number density, n, times the spherical volume, 0 = Ava nl2>. It is easy to show that the maximum packing fraction of spheres is 0 = 0.74 (see Problem XIV-2). Many physical properties of emulsions can be characterized by their volume fraction. The viscosity of a dilute suspension of rigid spheres is an example where the Einstein limiting law is [2]... 

The conductivity of a dilute emulsion can be treated by classic theory (see Maxwell [6]) assuming spherical droplets... 

Dissolve I ml. of benzaldehyde and 0-4 ml. of pure acetone in 10 ml. of methylated spirit contained in a conical flask or widemouthed bottle of about 50 ml. capacity. Dilute 2 ml. of 10% aqueous sodium hydroxide solution with 8 ml. of water, and add this dilute alkali solution to the former solution. Shake the mixture vigorously in the securely corked flask for about 10 minutes (releasing the pressure from time to time if necessary) and then allow to stand for 30 minutes, with occasional shaking finally cool in ice-water for a few minutes. During the shaking, the dibenzal -acetone separates at first as a fine emulsion which then rapidly forms pale yellow crystals. Filter at the pump, wash well with water to eliminate traces of alkali, and then drain thoroughly. Recrystallise from hot methylated or rectified spirit. The dibenzal-acetone is obtained as pale yellow crystals, m.p. 112 yield, o 6 g. 

Dichloramine-T. Dilute 80 ml, of freshly prepared 2N sodium hypochlorite soluticMi (preparation, p. 525) with 80 ml. of w ter, and then add with stirring 5 g. of finely powdered toluene-p-sulphonamide, a clear solution being rapidly obtained. Cool in ice-water, and then add about 50 ml. of a mixture of equal volumes of glacial acetic acid and water slowly with stirring until precipitation is complete the dichloro-amide separates at first as a fine emulsion, which rapidly forms brittle colourless crystals. Filter off the latter at the pump, wash well with... 

Inversion ofMon cjueous Polymers. Many polymers such as polyurethanes, polyesters, polypropylene, epoxy resins (qv), and siHcones that cannot be made via emulsion polymerization are converted into latices. Such polymers are dissolved in solvent and inverted via emulsification, foUowed by solvent stripping (80). SoHd polymers are milled with long-chain fatty acids and diluted in weak alkaH solutions until dispersion occurs (81). Such latices usually have lower polymer concentrations after the solvent has been removed. For commercial uses the latex soHds are increased by techniques such as creaming. 

Both regulatory limits on the amount of organic solvents allowed in paints and advancements in alkyd resin technology have resulted in the development of higher soHds alkyd resins that requke less solvent for dilution and viscosity reduction. In addition, developments of water-reducible alkyds and alkyd emulsions have resulted in alkyd-based paints that requke less organic solvent in thek formulations. 

Defoamers (qv) are available in several forms, composed of many different materials. Historically, paste and soHd defoamers were used extensively. Composed of fatty acids, fatty amides, fatty alcohols, emulsifiers (and mineral oil [8012-95-1] in the high soflds paste emulsions), these defoamers required emulsification (brick) or dilution (paste) before use. Liquid defoamers have become the preferred form, insofar as concern about handling and ovemse have been overcome. 

Paste rosin sizes are supplied as viscous pastes containing 60—80% solids. These sizes may contain unmodified or fortified rosin that has reacted (ie, been fortified) with either maleic anhydride [108-31-6] or fumaric acid [110-17-8] (see Fig. 3). In either case, the unmodified or fortified rosin is treated with aqueous alkaH so that the degree of neutralization, ie, saponification, varies from 75—100% depending on the physical state desired for the commercial product. Before use, the paste size must be converted to a stable, dilute rosin size emulsion by careful sequential dilution with warm water foUowed by cold water, with good agitation. 

Rosin sizing usually involves the addition of dilute aqueous solutions or dispersions of rosin soap size and alum to a pulp slurry (44—46). Although beater addition of either coreactant is permissable, addition of both before final pulp refining is unwise because subsequently exposed ceUulose surfaces may not be properly sized. The size and alum should be added sufficiendy eady to provide uniform distribution in the slurry, and adequate time for the formation and retention of aluminum resinates, commonly referred to as size precipitate. Free rosin emulsion sizes, however, do not react to a significant degree with alum in the pulp slurry, and addition of a cationic starch or resin is recommended to maximize retention of size to fiber. Subsequent reaction with aluminum occurs principally in the machine drier sections (47). 

The organic peroxides and peroxide compositions produced commercially are those that can be manufactured, shipped, stored, and used safely. Organic peroxides can be thermally and mechanically desensitized by wetting or by dilution with suitable solvents, iaert soHd fillers, or iasoluble Hquids (suspension of soHd peroxides ia Hquid plasticizers or water, and emulsions of Hquid peroxides ia water). 

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