Particle size distribution measurement of anisotropic—particles cylinders and platelets—practical examples

The measurement of particle size distributions (PSD) of model anisotropic particles with regular cylindrical or platelet morphologies has been previously studied with several different instruments, and good correlations with image analysis were found for certain specific measurement methods. The correlation was found to be dependent on particle morphology. For cylindrical glass fibres, photocentrifuge data gave good correlations with image analysis, whereas for platelets the laser diffraction method gave the best correlation with image analysis. The study has been enlarged to investigate less regular-shaped particles found in real practical systems, namely, flake-like particles of mica and rod-like copper oxalate precipitates. The correlation between laser diffraction data and image analysis for the flake-like mica is very good and confirms the approach used with model platelets. The copper oxalate rod-like precipitates also confirm the applicability of the photocentrifuge particle size distribution measurement for such particle shapes. In both cases, there are, however, limitations on the interpretation of the particle size instrument data. Some shape information from microscopic images is needed to make some assumptions to simplify the deconvolution of size and shape from the data collected.