Particle factors which control

The onset of high electrical conductivity with increasing volume fraction of metallic particles has also been of interest in relation to theoretical treatments which consider the factors which control formation of a continuous disperse phase of randomly distributed particles. In pursuance of such work, the distribution of metallic particles was studied experimentally by quantitative microscopy of polished plane sections. A marked increase in conductivity was observed when the fractional volume loading of silver particles in Bakelite reached 0.36-0.38 ( 3). 

The thermal treatment is one of the factors which controls the properties of the final catalyst [56]. The total surface area (in the range between 100 and 300m2g l) decreases with increasing reduction temperature however, the nickel surface area (typically 20-50 m2g l) increases which is probably due to a higher degree of reduction. The best precursor with respect to a high surface area is the hydroxycarbonate. The surface areas of catalysts prepared from hydroxy-chlorides and nitrates are smaller by about a factor of two. Nickel particle sizes are in the order of 5nm for such catalysts. 

The anisotropy of the physico-mechanical properties constitutes an important factor, which controls the mechanochemical destruction. Thus, the polymers characterized by isotropic properties are milled, forming particles with a reduced degree of asymmetry, so that a determined direction of the destruction process could not be noticed. This fact evidently comes out from the increase of the polymer anisotropy, implicitly characterized, as well by the increase of the asymmetry degree of the produced particles. 

Factors which adversely influence the separation of veiy fine particle systems are brownian motion and London forces. However, it is possible to counter these forces by the use of dispersants, temperature control, and so on. 

Stokes law This relates to the factors that control the passage of a spherical particle through a fluid. The Stokes diameter of a particle is the diameter of a sphere of unit density, which would move in a fluid in a similar manner to the particle in question, which may not be spherical. 

The product crystals were agglomerates of needles or dendrites. Loose floes of dendroid strontium carbonate are compacted by agitation, which is an important factor in controlling the habit of product particles. Semi-batch operation produces larger particles compared to batch or continuous operation. 

In this section we will discuss two studies that were performed to investigate factors which may effect particle size control (1) the type of support material and (2) the weight loading. 

Microstructures of CLs vary depending on applicable solvenf, particle sizes of primary carbon powders, ionomer cluster size, temperafure, wetting properties of carbon materials, and composition of the CL ink. These factors determine the complex interactions between Pt/carbon particles, ionomer molecules, and solvent molecules, which control the catalyst layer formation process. The choice of a dispersion medium determines whefher fhe ionomer is to be found in solubilized, colloidal, or precipitated forms. This influences fhe microsfrucfure and fhe pore size disfribution of the CL. i It is vital to understand the conditions under which the ionomer is able to penetrate into primary pores inside agglomerates. Another challenge is to characterize the structure of the ionomer phase in the secondary void spaces between agglomerates and obtain the effective proton conductivity of the layer. 

The rate of coagulation depends upon the collision frequency, which is controlled by physical parameters describing perikinetic or ortho-kinetic particle transport (temperature, velocity gradient, number concentration and dimension of colloidal particles), and the collision efficiency factor a measuring the extent of the particle destabilization which is primarily controlled by chemical parameters. 

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