Table of contents 1 Why is particle size important?

1
Particle size influences many properties of particulate materials and is 
a valuable indicator of quality and performance. This is true for powders, 
suspensions, emulsions, and aerosols. The size and shape of powders influences
flow and compaction properties. Larger, more spherical particles will typically flow
more easily than smaller or high aspect ratio particles. Smaller particles dissolve 
more quickly and lead to higher suspension viscosities than larger ones. Smaller 
droplet sizes and higher surface charge (zeta potential) will typically improve 
suspension and emulsion stability. Powder or droplets in the range of 2-5µm 
aerosolize better and will penetrate into lungs deeper than larger sizes. For these 
and many other reasons it is important to measure and control the particle size 
distribution of many products.
Measurements in the laboratory are often made to support unit operations taking 
place in a process environment. The most obvious example is milling (or size 
reduction by another technology) where the goal of the operation is to reduce 
particle size to a desired specification. Many other size reduction operations and
technologies also require lab measurements to track changes in particle size 
including crushing, homogenization, emulsification, microfluidization, and others.
Separation steps such as screening, filtering, cyclones, etc. may be monitored by
measuring particle size before and after the process. Particle size growth may be 
monitored during operations such as granulation or crystallization. Determining the 
particle size of powders requiring mixing is common since materials with similar and 
narrower distributions are less prone to segregation. 
There are also industry/application specific reasons why controlling and
measuring particle size is important. In the paint and pigment industries particle 
size influences appearance properties including gloss and tinctorial strength.
Particle size of the cocoa powder used in chocolate affects color and flavor. The size
and shape of the glass beads used in highway paint impacts reflectivity. Cement
particle size influences hydration rate & strength. The size and shape distribution
of the metal particles impacts powder behavior during die filling, compaction, and
sintering, and therefore influences the physical properties of the parts created.
In the pharmaceutical industry the size of active ingredients influences critical
characteristics including content uniformity, dissolution and 
absorption rates. Other industries where particle size plays an important role include 
nanotechnology, proteins, cosmetics, polymers, soils, 
abrasives, 
fertilizers, and 
many more.
Why is 

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