Flakiness ratio

While the shape factor, introduced in the previous section, provides a quantitative definition or description of particle shape, there are other descriptors such as flakiness ratio, flakiness index, elongation index and angularity number which are also found to be in vogue. 

Sphericity shape factor Circularity shape factor 1 W where a0 = shape factor for equidimensional particle and thus represents part of av which is due to geometric shape only av = volume shape coefficient m = flakiness ratio, or breadth/thickness n = elongation ratio, or length/breadth Sphericity = (surface area of sphere having same volume as particle) / (surface area of actual particle) Circularity = (perimeter of particle outline)2 / 4tr(cross-sectional or projection area of particle outline)... 

The earliest methods of describing the shape of particle outlines used length L, breadth B, and thickness T in expressions such as the elongation ratio (L/B) and the flakiness ratio (B/T). The drawback with simple, one number shape measurements is the possibility of ambiguity the same single number may be obtained from more than one shape. Nevertheless, a measurement of this type which has been successfully employed for many years is the so-called sphericity, defined by the relation... 

Smooth jaws produce more numerous flaky pieces than corrugated jaws. Curved jaws produce less fines but more numerous flaky particles. Crusher speed has little effect. The presence of material too small to be crushed has a deleterious effect on the shape of products. Secondary crushers with a small reduction ratio can improve the shape of primaiy crushed material, but secondaiy crushers are not inherently different from primaiy crushers. Slotted screens can remove flaky particles from the product. Impact crushers produce fewer flaky particles than any other type. 

As far as conducting fillers are concerned, we have rather a wide range of choice. In addition to the traditional and long used fillers, such as carbon black and metal powders [13] fiber and flaky fillers on organic or metal bases, conducting textures, etc recently appeared and came into use. The shape of the filler particles varies widely, but only the particle aspect ratio, the main parameter which determines the probability... 

Depolarization of one-shot seattered radiation is stipulated by deviation of the particles shape from a spherical form. The D ratio in the depolarization layer of 2.5-3.5 km is practically constant and does not exceed 0.20-0.25 at a sharp inerease of the backscattering ratio R at 3.0 km It shows that the aerosol from Iraq is represented mainly by non-spherieal particles. The vertical level-by-level cut shows a flaky stracture of aerosol particles. 

The main factors that affect the particle passage through sieve aperture are the method of sieve shaking, the ratio of open area of sieve to total area, particle size distribution, the number of particles on the sieve (sieve loading), and the dimension and shape of the particle. Friability and cohesiveness of solid particles can also affect the sieving operation. Difficulty can also arise with high aspect ratio particles (i.e., needle-shaped or flaky particles). 

PHE (0.5% solution in chloroform) has a reduced viscosity of equal to 0.044 m /kg at 295 K. PHE was dissolved in the mixture of two solvents 1,4-dioxane and N,N-dimethyl acetamide with a ratio (by weight) of 1 1. To the solution with a concentration of 17% of polymer, flaky graphite was added in the necessary amount and after this procedure the dispersion was poured into water. 

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