Density, of powders

The bulk density of powdered diatomite varies from 112 to 320 kg/m. The tme specific gravity of diatomite is 2.1 to 2.2, the same as for opaline sihca, or opal (1). The thermal conductivity of bulk quantities of diatomite is low but increases with higher percentages of impurities and a higher density. The fusion point depends on the purity but averages about 1430°C for pure material, which is slightly less than for pure siUca. The addition of chemical agents, such as soda ash, reduces the fusion point. 

The bulk factor (i.e. ratio of the density of the moulding to the apparent powder density) of powder is usually about 2-3 but the high-shock grades may have bulk factors of 10-14 when loo.se, and still as high as 4-6 when packed in the mould. Powder grades are quite easy to pellet, but this is difficult with the fabric-filled grades. 

Size, Particle Size Distribution, and Packed Density of Powdered Materials , MIL-STD-1233 (March 1962) 3) Anon, EngDesHdbk, Pro-... 

Mercury porosimetry provides a convenient method for measuring the density of powders. This technique gives the true density of those powders which do not possess pores or voids smaller than those into which intrusion occurs at the highest pressure attainable in the porosimeter and provides apparent densities for those powders that have pores smaller than those corresponding to the highest pressure. 

The rapid growth of interest in powders and their surface properties in many diverse industries prompted the writing of this book for those who have the need to make meaningful measurements without the benefit of years of experience. It is intended as an introduction to some of the elementary theory and experimental methods used to study the surface area, porosity and density of powders. It may be found useful by those with little or no training in solid surfaces who have the need to quickly learn the rudiments of surface area, density and pore-size measurements. 

To control the pattern size, shape, and density of powder... 

Dautriche found the density of powdered and compressed TNT to be as follows ... 

Particulate catalysts are usually sold by weight but are charged to a reactor by volume. Thus, the density of the support has a strong impact on the economics of the process. Fluidization in moving-bed reactors is also dependent on catalyst density. The density of powders affects the extent to which they can be suspended and eventually settled in slurry-phase reactors. 

Besides particle size and dmg concentration, particle shape and density of powders are also important factors for achieving a homogenous mixture. Powders with nearly spherical particles are easier to mix than those with irregularly shaped particles. Micronized, needle, or flat particles require longer blending time due to aggregate... 

The bulk density of powders can be measured very simply by weighing a sample in a volume-graduated container, perhaps after using a standardized tapping procedure to uniformly consolidate the sample. 

To define bulkiness in detail, the porosity and density of powders should be understood. Suppose a powder, such as zinc oxide, is placed in a graduated cylinder and the total volume is noted. The volume occupied is known as the bulk volume Vb. If the powder is nonporous, that is, has no internal pores or capillary spaces, the bulk volume of the powder consists of the true volume of the solid particles plus the volume of the spaces between the particles. The volume of the spaces, known as the void volume v, is given by equation... 

Mercury Porosimetry Method Mercury is a nonwetting liquid that must be forced to enter a pore by application of external pressure. Consequently it is an extremely useful and convenient liquid for measuring the density of powders and/or particles. This method can measure the apparent and true density of one sample by... 

MIL-STD-1233 — Procedure for Determining Particle Size Distribution and Packing Density of Powdered Material MIL-STD-1235 — Single and Multilevel Continuous Sampling Procedures and Tests for Inspection by Attributes 2.2 Other Publications See Spec, pp 1 2 3. REQUIREMENTS... 

Pt, density of powder pi, initial apparent density of powder Pc, density of powder applied pressure Pa. K, a,h and c are constants. 

Any of the three particle densities defined above should not be confused with bulk density of materials which includes the voids between the particles in the volume measured bulk density of powders is dealt with in another section of this guide (section 5.2). 

Sometimes the density of powder compacted over and above what can be achieved by tapping may be needed. There are no standard procedures for this other than the rather specialized soil compaction tests and density determinations (2.5 and 4.5 kg rammer methods) quoted in a British Standard for soils16. 

It is in the relatively simply-measured properties where most problems lie. Bulk densities of powders (particularly the tap... 

Density can be defined as ratio of the mass of an object to its volume therefore, the density of a solid is a reflection of the arrangement of molecules in a solid. In pharmaceutical development terms, knowledge of the true density of powders has been used for the determination of... 

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