Study Set Content:
volume occupied
Bulk volume –
Bulk volume symbol
Vb
volume of space
Void volume
Void volume symbol
v
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
f 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.
Powder beds of uniform-sized spheres can assume either of two ideal packing arrangements:
Closest or rhombohedral
Most open, loosest, or cubic packing
-26%
Closest or rhombohedra
- 48%
Most open, loosest, or cubic packing
The particles in real powders are neither spherical in shape nor
uniform in size
Most powders in practice have porosities between
30% and 50%.
If the particles are of greatly different sizes, however, the smaller ones may shift between the larger ones to give porosities below the theoretical minimum of
26%
In powders containing flocculates or aggregates, which lead to the formation of bridges and arches in the packing, the porosity may be above the theoretical maximum of
48%
Crystaline
1%
3 types of density
True Density
Granule Density
Bulk Density
he material itself, exclusive of the voids and intraparticle pores larger than molecular or atomic dimensions in the crystal lattices.
True Density
Can be determined by a method similar to the liquid displacement method.
Granule Density
The density of the actual solid materia
True Density
use of helium (penetrates into the smallest pores and crevices) densitometer]
Porous
is used because it fills the void spaces but fails to penetrate into the internal pores of the particles
Mercury
