Density, powder effective

C. In low density powdered (or porous) explosives, there are two main opposing effects "dilution and "penetration ... 

Superko, H.R. and Krauss, R.M. 2000. Garlic powder, effect on plasma lipids, postprandial lipemia, low-density lipoprotein particle size, high-density lipoprotein subclass distribution and lipoprotein(a). J. Am. Coll. Cardiol. 35, 321-326. 

Sufficient vacuum deaeration must be effectively distributed prior to the nip roll region, particularly for low bulk density powder feed stock. 

Streubel, A. Siepmann, J. Bodmeier, R. Floating matrix tablets based on low density foam powder Effects of formulation and processing parameters on drng release. Eur. J. Pharm. Sci. 2003, 18(1), 37-45. 

Powder Density. See true density. Powdering. A process sometimes used for the on-glaze decoration of the more expensive types of pottery-ware. Colour mixed with an oil medium is first brushed on the ware, dry powdered colour then being applied to achieve a stippled effect. 

It should also be noted that the presence of surface modifiers can also influence other properties. This includes properties such as bulk density, powder flow and dustiness. They can also have unexpected effects on properties such as thermal stability, fire retardancy and ageing. These effects may be positive or negative. 

The characteristics of a powder that determine its apparent density are rather complex, but some general statements with respect to powder variables and their effect on the density of the loose powder can be made. (/) The smaller the particles, the greater the specific surface area of the powder. This increases the friction between the particles and lowers the apparent density but enhances the rate of sintering. (2) Powders having very irregular-shaped particles are usually characterized by a lower apparent density than more regular or spherical ones. This is shown in Table 4 for three different types of copper powders having identical particle size distribution but different particle shape. These data illustrate the decisive influence of particle shape on apparent density. (J) In any mixture of coarse and fine powder particles, an optimum mixture results in maximum apparent density. This optimum mixture is reached when the fine particles fill the voids between the coarse particles. 

When used in blasting, ammonium nitrate is mixed with fuel oil and sometimes sensitizers such as powdered aluminum. Lower density ammonium nitrate is preferred for explosive formulation, because it absorbs the oil more effectively. When detonated,these mixtures have an explosive power of 40 to 50% that of TNT (see Explosives and propellants). 

The success of the compaction operation depends pardy on the effective utilization and transmission of appHed forces and pardy on the physical properties and condition of the mixture being compressed. Friction at the die surface opposes the transmission of the appHed pressure in this region, results in unequal distribution of forces within the compact, and hence leads to density and strength maldistribution within the agglomerate (70). Lubricants, both external ones appHed to the mold surfaces and internal ones mixed with the powder, are often used to reduce undesirable friction effects (71). For strong compacts, external lubricants are preferable as they do not interfere with the optimum cohesion of clean particulate surfaces. Binder materials maybe used to improve strength and also to act as lubricants. 

MeutralSoluble Salts. So dium sulfate [7757-82-6] and, to a considerably lesser extent, sodium chloride [7647-14-5] are the principal neutral soluble salts used in laundering compositions. They are often considered to be fillers although they perform an important standardizing function enabling the formulator to manufacture powders of a desired, controlled density. Sodium sulfate, in addition, lowers the critical micelle concentration of organic surfactants and thus the concentration at which effective washing can be achieved. 

Foam Insulation Since foams are not homogeneous materials, their apparent thermal conductivity is dependent upon the bulk density of tne insulation, the gas used to foam the insulation, and the mean temperature of the insulation. Heat conduction through a foam is determined by convection and radiation within the cells and by conduction in the solid structure. Evacuation of a foam is effective in reducing its thermal conductivity, indicating a partially open cellular structure, but the resulting values are stiU considerably higher than either multilayer or evacuated powder insulations. 

As in the case of road tankers there are no available case histories of PBDs in lined rail cars for liquids. However, owing to the large charge densities developed in some powder transfers the effect of linings may need serious consideration for rail cars in powder service (6-4.3). 

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