Author: Andrew K Long
Source: ezinearticles.com
Calculating the size, shape, and mass of microscopic particles in a suspension is seemingly a daunting task at best. Particles in the micrometer, or micron, size can move very quickly in an aerosol, for example, and determining their size and shape while they are flitting about in the dispersion would require extremely sensitive instruments. Particle sizing equipment must enter into this ambiguous and difficult analytical process.
There are several methods for particle sizing. One such method is the so-called sedimentation method. This procedure is mostly straight forward, as an emulsion of known or unknown particles in a known liquid are slowly settled in a tube, and optical sensors detect the sizes, shapes and settling velocities in a matter of minutes. An excellent sedimentation instrument can provide results in as fast as fifteen minutes.
Sedimentation of the particles can reveal many properties of the material being analyzed. The mass of each particle can be determined by the velocity in which the particles settle in the known liquid. Knowing the viscosity of the liquid in which the particles are suspended can give the analyzer calculation to the particles mass, as gravity affects different masses in a known solution. Emulsions of materials that are to be analyzed that belong in the same state can be separated into the different particles that make them up, thus giving an accurate physical attributes to the materials and how they behave after manufacturing.
Paints that use specific pigments can be analyzed for quality control using this method, and it is also an invaluable tool for chemical engineers who design solutions and emulsions for many industries, including agriculture, pharmaceutical, and cosmetics. Pigments come in particulates before being emulsified into the household paint matrix, and having the proper size for the pigmentation particles is crucial. Too large a particle and the paint would coat in an uneven color, too small and the pigment may not be brought out after the paint dries.
Laser light backscatter particle sizing is one of the most innovative methods to date. Laser light is a pure coherent light, and the beam can be focused and adjusted for nearly any particulate matter being analyzed. Powders and aerosols, which can be very difficult to analyze, are discerned in this manner, and laser refraction and diffraction can be so precise that individual nanometer-sized particles can be measured.
The Lorenz-Mie Theory is the rule by which the calculations are made for the determination of particle size and shape after the arbitrary light beam is scattered when striking a spherical particle. It must be understood, however, that most particles in an aerosol are particularly spherical, so this method must also be used to determine shape. Many particles in powders maintain roughly the same size and shape, depending on the material that is pulverized. Talc, for example, has different sizes, which can result in different properties of the powder. Since talcum is used in many industrial methods, getting the right size before fabrication of certain dependant materials is crucial. Particle sizing instruments enable manufacturers to guide the quality of materials by maintaining the proper particle sizes.
Particle sizing is a crucial part of many material manufacturing processes, and since there are many proven and reliable methods for analyzing particle sizes, quality control is an area that has improved in its own right.
Take a look at other relevant particle sizing information including particle size analyzer resources as well as particle size analysers related material.
