Dispersed solid particles

Disperse solid particles in a viscous fluid Laminar 10... 

The addition of finely dispersed solid particles improves the IR absorption of the polymer and positively influences blowing of the preforms. Such solid particles can be obtained by the reduction of Sb3+ to metallic antimony during polycondensation by the addition of trivalent phosphorous compounds such as phosphonic acid or its esters (phosphites). However, only a slight improvement in properties could be achieved by this approach [35],... 

It is important to differentiate between the two different types of sorption/ desorption tests (i. e.,batch and column-leaching), and the sorption characteristics determined from one should not be confused with the other. Sorption isotherms obtained with batch equilibrium tests are applied mainly to solid suspensions. The physical model, assumed with this situation, is one of a completely dispersed solid particle system, where all solid particle surfaces are exposed and available for interactions with the contaminants of concern. In contrast, column-leaching tests are performed with intact solid samples, and the sorption characteristics obtained from them are the results of contaminant interactions with a structured system where not all-solid particle surfaces are exposed or available for interactions with the contaminants. 

FIG. 13.13 Interaction between polymer-coated particles. Overlap of adsorbed polymer layers on close approach of dispersed solid particles (parts a and b). The figure also illustrates the repulsive interaction energy due to the overlap of the polymer layers (dark line in part c). Depending on the nature of the particles, a strong van der Waals attraction and perhaps electrostatic repulsion may exist between the particles in the absence of polymer layers (dashed line in part c), and the steric repulsion stabilizes the dispersion against coagulation in the primary minimum in the interaction potential. 

The work was planned on the basis of a model of a dispersed solid particle onto which one type of sequences of a BG copolymer is adsorbed selectively while the other type sequence is dissolved in the dispersion medium. A sketch of this model is shown in Figure 1. The model is the result of applying the same arguments which had been advanced (12) in discussing the mechanism of stabilization of polymeric oil-in-oil emulsions by BG copolymers to the problem of stabilization of dispersions of solid particles in organic media. Previously, essentially the same arguments had led to the demonstration of micelle formation of styrene-butadiene block copolymers in organic media under certain conditions (15). 

The effects of improved wettability, entropic repulsion, and sterical hindrance undoubtedly play a role in stabilizing dispersed solid particles by block or graft copolymers. However, since the dispersions of titanium dioxide in toluene stabilized by carboxylated styrene-butadiene block copolymers are so much more stable than dispersions stabilized by carboxylated homopolymers under otherwise identical conditions, we must assume that an additional factor comes into play when block copolymers are used. The model in Figure 1 is an attempt to explain this additional... 

Foams and emulsions may also be encountered simultaneously [114]. Figure 1.5 shows an example of an aqueous foam with oil droplets residing in its Plateau borders (see Section 5.6.7). In addition to containing gas, an aqueous phase, and an oleic phase, foams can also contain dispersed solid particles. Oil-assisted flotation of mineral particles provides one example (Chapter 10). Oil-sand flotation of bitumen provides another (Chapter 11). In the case of oil-sands flotation, an emulsion of oil dispersed in water is created and then further separated by a flotation process, the products of which are bituminous froths that may be either air (and water) dispersed in oil (from primary flotation) or air (and oil) dispersed in water (from secondary flotation). In either case, the froths must be broken and de-aerated before the bitumen can be upgraded to synthetic crude oil. (See Section 11.3.2). 

Triisobutylaluminum, which is used as a component of a catalyst for the production of olefines, should contain not more than 0.01% finely dispersed solid particles. The product obtained by direct synthesis contains up to 5% of solid impurities, mostly 0.1-1 pm aluminum particles. If this product is purified by centrifuging, even subsequent settling (for 24 hours or more) cannot reduce the concentration of solid particles to the required level therefore, it is advisable to replace centrifuging with kieselguhr or perlite filtering. 

The use of finely dispersed solid particles as stabilisers of O/W and W/O emulsions has been known since last century. In a number of works [73-77] it has been established that there is a close relationship between the type and stability of emulsions, stabilised by solid particles and the value of the contact angle at the solid body/water/organic liquid interface. A... 

The viscosity of the mixed oils is higher than that of the bagasse and the PR individually. This is due to the formation of con Iex three component emulsions (biooil, PR-derived hydrocarbons and water) with dispersed solid particles. As expected, the mixed oils exhibit non-Newtonian flow behaviour (herein not shown). The con lex emulsion obtained seems to be more stable than the one obtained by mixing die oils produced separately from bagasse and PR. The oils from bagasse, PR and the mixed oils were also observed by microscopy. The existence of three liquid emulsions was confirmed by microscopic analysis (Figure 4). 

COLLOID GROUT A grout in which the dispersed solid particles remain in suspension (colloids). 

Elghobashi SE, Truesdell GC (1993) On the two-way interaction between homogeneous turbulence and dispersed solid particles. I Turbnlence modification. Phys Fluids A5 (7) 1790-1801... 

In the pH measurement the reference and indicator electrodes are immersed in a heterogeneous soil suspension comprising of dispersed solid particles in an aqueous solution. If the solid particles are allowed to settle down, the pH can be measured in the supernatant liquid or in the sediment. Placement of electrode pair in the supernatant normally gives a higher pH reading than placement of the same in the sediment. The difference in soil pH reading is called the Suspension effect . 

When the aqueous system contains finely divided solids, then foaming of the system may be influenced greatly by the nature of the dispersed solid particles. If the particles have a surface that is hydrophobic, and if the particles are divided finely enough, then the particles may adsorb onto the surface of any air bubbles introduced into the system and stabilize them against coalescence. They adsorb at the air-solid interface from the aqueous system because their solid-aqueous solution interfacial tension, ySL, is high and their solid/(nonpolar) air interfacial tension, ySA, is low because of their nonpolar surface. Consequently, their contact angle, 0, with the aqueous phase, from equation 6.3... 

Figure 13 Steric stabilization caused by the overlap of adsorbed polymer layers upon close approach of dispersed solid particles.

Not less complicated processes are observed in the interaction of flotation agents with finely dispersed solid particles. A special class of the so-called collecting agents is singled out which selectively adsorb on the particles flotated. Classically, three main adsorption mechanisms are pointed out here 1) the so-called physical adsorption occurring due to the opposite electrokinetic potential values of the solid particle and the nature of the surfactant ion 2) chemical adsorption occurring due to the chemical reactions of surfactant ions with the surface ions of the particles flotated 3) formation of complex compounds on the surface. 

Similarly, in the solid in oil in oil (s/o/o) double emulsions, the internal solid phase and external oil phase are separated by an oil phase. The s/o/o emulsion can be prepared by dispersing solid particles in an organic solvent, for example, methylene chloride, and then mixed with a polymer solution. Alternatively, the dispersion of solids in organic solvent can be coated with a suitable polymer using a coacervation technique. 

Chem. Descrip. Hydrophobic org. active matter and dispersed solid particles... 

The viscosity characteristics of liquids can be altered considerably by the presence of finely dispersed solid particles, especially of colloidal size. The viscosity of a suspension of rigid spherical particles in a liquid, when the distance between the spheres is much greater than their diameter, may be expressed by the Einstein equation ... 

Once equilibrium has been attained, i.e. when the originally over- and undersaturated solutions are of equal composition, the mixture is allowed to stand for an hour or more, at the relevant constant temperature, to enable any finely dispersed solid particles to settle. The withdrawal of a sample of clear supernatant liquid for analysis can be effected in a number of ways, depending on the characteristics of the system. For example, a suitably warmed pipette, with the tip protected by a piece of cotton wool, glass wool or similar substance, is often quite adequate. The pipette may be warmed to the appropriate temperature by leaving it standing in a stoppered tube immersed in the thermostat bath. Alternatively, a variety of sintered glass filters can be utilized Figure 3.5) (Nyvlt, 1977). In all cases, several portions of solution should first be withdrawn and discarded to satisfy any possible capacity of the filter to adsorb solute from the saturated solution (Void and Void, 1949). The sample of saturated solution may then be analysed by any convenient technique (section 3.9.2). 

Disodium stearyl sulfosuccinamate PEG-40 lanolin PEG-50 lanolin PEG-85 lanolin dispersant, soil suspending Laureth-6 Laureth-14 Laureth-30 dispersant, soil detergents Sodium polyaspartate dispersant, soil hard-surface cleaners Sodium polyaspartate dispersant, solid particles Diethylene triamine pentamethylene phosphonic acid dispersant, solids... 

Flotation is a technique to separate finely dispersed solid particles based on different surface wettabilities. The principle of flotation is illustrated in Figure 8.11. Air bubbles are blown through a slurry of solid particles dispersed in a liquid. In the case of an aqueous liquid, the more hydrophobic particles attach to the air bubbles that pass through the liquid and arrive in the froth, leaving the hydrophilic particles behind in the bulk liquid. 

B. Adsorption of Binary Liquid Mixtures on Dispersed Solid Particles... 

Due to the interfacial curvature, the pressure Pb is lower and the film is thicker in the plateau border, so that a sucking effect on the liquid from the centre of the film to its periphery occurs. The pressure difference between neighbouring cells (Ap) is related to the radius of curvature (r) of the plateau border by Ap = ly jr. The resulting thin film structure, on thinning to about 1000 nm (where interference colours are observed), is referred to as a polyederschaum. The terms foams and froths are often used interchangeably, but it is more usual to refer to the gas-water macrocluster systems where the broken structure leaves a homogeneous aqueous phase as a foam. The froth usually contains dispersed solid particles, so that the broken structure gives a two-phase system (aqueous solution and finely divided particles). 

A colloidal sol is generally a substance Giquid or gel) containing dispersed solid particles. To obtain a homogeneous and stable system, the size of the nanoparticles has to be small, say below 100 nm. 

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