Charged particle surface area

Another way of disappearance of nonequilibrium charge carriers is their recombination at the particle surface (radiative with the rate constant ks>r, and nonradiative with the rate constant ks>n). Of basic importance is the question of whether the surface recombination sites are the sites of the quencher adsorption. In other words, is the quencher adsorption able to result in disappearance of the surface recombination sites. With positive answer, the expression for the surface recombination rate should be written as (k + ks,n)-S-(l - 0a)-e-h, where S is the particle surface area, and 0a is the surface fraction occupied by the quencher (electron acceptor). Otherwise, the latter multiplier (1 - 0J should be excluded. Further we will consider the both cases (1 and 2), compare them with experimental data and choose the case providing a better description of the phenomena observed. 

ZA is the charge number of the diffusing ion F is the Faraday constant S is the particle surface area r is the particle length. 

The conditions necessary to achieve DDT depend upon such factors as confinement, particle size, particle surface area, packing density, charge diameter and length, heat transfer, and thermochemical characteristics of the particular explosive. 

Design of electrostatic classifiers and precipitators is based on the principle that the electrostatic charge generated on a particle is proportional to the particle surface area. Furthermore, the behavior of particles in an electric field is controlled by the presence and amount of the electrostatic charge residing on the particle surfaces. 

The objective of this work was to characterise the sodium dodecyl allyl sulphosuccinate (Eliminol JS-2) stabilised poly(butyl acrylate) (PBA) lattices produced in a semibatch reactor. The PBA latex particles were prepared using a semibatch pulsion polymerisation process. It was found that the concentration of JS-2 or sodium dodecyl sulphate present in the initial reactor charge is very important in determining the final latex particle size. The higher the particle size polarity is, the larger is the saturated particle surface area covered by one JS-2 molecule. It was also found that at a common surfactant concentration, the JS-2 stabilised latex displays reduced chemical stability than the sodium dodecyl sulphate stabilised latex. The results of such research should be useful to tape and label manufacturers. 3 refs. 

This, in turn, is dependent upon the volume of the particle being formed. The relationship between particle surface area and volume is not linear. This is observed experimentally as the response curves for the Corona charged aerosol detector are typically expressed as the second-order polynomial function over a range of up to four orders of magnitude. However, over a narrow concentration range, good linearity of the CAD response is observed with sufficient accuracy. The application of power function can now correct for this physical characteristic and deliver a more linear response over a larger dynamic... 

The colloidal properties of latex products are of great importance from both academic and industrial points of view. Some representative charaeteristics include the particle size and particle size distribution, the particle surface charge density (or zeta potential), the particle surface area covered by one stabilizer molecule, the conformation of the hydrophilic polymer physically adsorbed or chemically couplet onto the particle surface, the type and concentration of functional groups on the particle surface, the particle morphology, the optical and rheological properties and the colloidal stability. 

Surface charge density, dq, is termed the charge quantity, q, of a spherical particle with radius, r, divided by the particle surface area... 

The concise Harkins-Smith-Ewart theory [9-16] delicately describes the key characteristics of emulsion polymerization. However, the difference in colloidal properties (e.g., composition, size, surface charge density, and particle surface area occupied by the adsorbed surfactant) between the monomer-swollen micelles and particle nuclei was not taken into account in the derivation of Eq. (3.4). The probability for micelles or particle nuclei to capture oligomeric radicals in the continuous aqueous phase is simply assumed to be proportional to their total oil-water interfacial area. 

Chern and Chen [30] studied the effect of the reactive surfactant, sodium dodecyl allyl sulfosuccinate, on the semibatch emulsion polymerization of n-butyl acrylate initiated by sodium persulfate. Sodium dodecyl allyl sulfosuccinate plays a similar role in the particle nucleation and growth stages to the conventional sodium dodecyl sulfate. The final number of latex particles per unit volume of water is proportional to the concentration of sodium dodecyl allyl sulfosuccinate in the initial reactor charge (the most important parameter with regard to particle nucleation) to the 0.72-0.80 power. The saturated particle surface area occupied by one molecule of sodium dodecyl allyl sulfosuccinate is 0.36 nm for the poly (n-butyl acrylate) particles prepared by the... 

Radicals generated from water-soluble initiator might not enter a micelle (14) because of differences in surface-charge density. It is postulated that radical entry is preceded by some polymerization of the monomer in the aqueous phase. The very short oligomer chains are less soluble in the aqueous phase and readily enter the micelles. Other theories exist to explain how water-soluble radicals enter micelles (15). The micelles are presumed to be the principal locus of particle nucleation (16) because of the large surface area of micelles relative to the monomer droplets. 

Silica sols are often called colloidal silicas, although other amorphous forms also exhibit colloidal properties owing to high surface areas. Sols are stable dispersions of amorphous siUca particles in a Hquid, almost always water. Commercial products contain siUca particles having diameters of about 3—100 nm, specific surface areas of 50—270 m /g, and siUca contents of 15—50 wt %. These contain small (<1 wt%) amounts of stabilizers, most commonly sodium ions. The discrete particles are prevented from aggregating by mutually repulsive negative charges. 

In most cases, the impregnation process is followed by an electrochemical formation where the plaques are assembled into large temporary cells filled with 20—30% sodium hydroxide solution, subjected to 1—3 charge—discharge cycles, and subsequentiy washed and dried. This eliminates nitrates and poorly adherent particles. It also increases the effective surface area of the active materials. 

So far the discussion has been limited to the case where the particle s charge is uniformly distributed. However, as discussed by researchers such as Goel and Spencer [89], and Hays [76,81], this might not be the case, especially if the particle is irregularly shaped. This can occur, as argued by Hays, if asperities on the particle prevent much of the surface area from contacting a neighboring... 

Ill the case of a toner particle, the charge q on the particle was produced by triboelectrification. As such, it is fair to assume that the charge is uniformly distributed and proportional to the surface area, with a proportionality constant attraction between the particle and the substrate is obtained using the method of images, discussed previously. Accordingly,... 

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