Particle Size Analysis
H&M offers various characterization techniques to adequately measure and analyze your sample. While particle size analysis can be a simple and straightforward operation, it can provide extremely vital information for the manufacturing and production of different products. In the field of chemistry the surface area of a particle is a determining factor in finding the rate of reaction. Fine or smaller particles are more likely to undergo chemical reactions. This is important in the concrete/cement industry and the particle sizes must be known and controlled. It is also important in the manufacturing of pharma related products, specifically for drugs delivered by inhalation. The body can filter out particles that are above a specific size, so nasally inhaled drugs need to have particles below that threshold to ensure the effectiveness of the drug.
This covers a wide area and 3 different techniques are utilized to cover a multitude of particle size analysis: light scattering, high resolution imaging and size broadening using X-ray diffraction.
Laser light scattering involves a laser beam passing through a sample of dispersed particulates and the particles will diffract light, with smaller particles diffracting at larger angles and larger particles diffracting at smaller angles. The actual size of the particle is then determined by using the Mie scattering theory. It is calculated by measuring the variation in the intensity of the scattered light as a function of the scattering angle. This test method works for particles in the range of 10 nm to 3 mm. This is a wide particle size range, but the test is accurate down to 0.6%.
High resolution imaging using SEM or FESEM devices is another way to collect particle size data. This provides another level of analysis as it can show the particle morphology and habit planes, which are not available by other techniques. A common use of SEM is to examine the grain size and morphology of grains or powders within a sample.
The third way to obtain particle size data is to utilize the line broadening method of XRD to compute average crystalite size and distributions within particles ranging from 1 to 100 nm. This is useful when analyzing catalysts where the particles are too small for the other 2 methods.
Main Applications of Particle Size Analysis
- Determining average particle size and particle size distribution
- Asthma inhaler manufacturing
- Cement production
- Quality control for inks
- Ceramic manufacturing from powders
- Cosmetics manufacturing
- Soils and sediments
- Semisolid pharmaceuticals
- Small sample size
- Wide range of particle sizes can be measured
- Extremely accurate and precise
- Possible to measure dilute systems
- Dry samples can be analyzed
- Particles can be examined individually
- Visual evidence to observe sub-micron particles
- The physical shape can be measured
- Small crystallites can be measured
- Quick testing
- Dispersant choice can interfere with detection
- Multiple light scattering can effect accuracy
- Certain materials can be difficult or impossible to prep
- Low throughput
Cosmetic Powders Analysis
The cosmetic industry produces many different products that include small particulates such as facial powders, moisturizers and lipsticks. Facial powders can consists of talc, iron oxides, kaolin and titanium oxide. In order to produce a successful product the particle size and the distribution of all of the components must be controlled. The distribution of the particles can effect the powders physical appearance and the even its stability.
SEM Imaging of Impurities for Failure Analysis
Failure analysis of materials is a common practice in both industry and research and development processes. A practical first step is to observe the material in a SEM to get a good up close look at the issue. At that point, a closer examination of the particles and grains can lend itself to possible reasons for the failure. Knowing the composition and desired particle size distributions of failed section can provide even more data. If the particles are too large, it could mean that the material in question did not undergo the required chemical reaction during production, thus leading to additional unwanted stress or strain in the material. The advantage of observing the material under SEM is that visual evidence of particle size, shapes and interactions can be found.