PARTICLE SIZE ANALYSIS
www.horibalab.com PARTICLE SIZE ANALYSIS DOWN TO THE NANOMETER RANGE
The HORIBA LA-950 analyzer quickly and accurately measures fi ne particles starting from 10 nm In the previous articles, the performance of RETSCH ball mills for pulverization was impressively demonstrat- ed. All size distributions that are represented in the different reports have been measured using the particle size analyzer LA-950 by HORIBA. This analyzer operates according to the principle of static laser light scat- tering, which is also frequently referred to as laser diffraction.
Fig. 1: LA-950 laser particle analyzer
The demands placed on a measurement system for the evaluation of grinding results are very high: fi rst, a wide measurement range is required because the initial particle size is often a few millimeters, while the fi neness of the fi nal product may lie in the nanometer range. In the course of the grinding process, larger particles of the original mate- rial that still need to be pulverized can be found alongside particles which have already been ground to a size in the nanometer range. In order to document the grinding process comprehensively, the analyses are often carried out in very short time intervals. Accordingly, the particle analyzer should provide both a high sample throughput and short analysis times. Since pulverizations are carried out in a variety of liquids, the measuring device should accept various dispers- ing media.
STATIC LASER LIGHT SCATTERING ANALYSIS
These requirements are best met with a particle analyzer which operates according to the principle of static laser light scatter- ing analysis (SLS). The measuring principle is based on the fact
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that particles, when interacting with laser light, scatter the light in characteristic angles with characteristic intensities. Whereas large particles scatter the light more strongly in the small angle range, small particles direct the light more strongly in the large angle range. By recording the light scattering pattern of a sam- ple within the largest possible angle range, the particle size distribution can be calculated according to specific algorithms. These algorithms are implemented in the LA-950 software.
LASER GRANULOMETER HORIBA LA-950
An outstanding feature of the laser particle analyzer LA-950 is its high flexibility. This applies to both the measuring range as well as the sample introduction. Ultrafine pulverizations are usually carried out in liquids, therefore the analysis is carried out in suspensions. The LA-950 offers the possibility to use different dispersing media: typically water or alcohol (2-propanol, ethanol, etc.), but also non-polar organic sol- vents such as hexane, heptane, or toluene may be employed. Via an auto-fill pump, the system is automatically filled with the dispersing medium. After the sample is introduced, it
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