The use of 3D prints to assess the influence of shape on particle size distribution in the laser diffraction method

Particle size distribution (PSD) is an important characteristic of many materials. Increasingly, this characteristic is determined using the laser diffraction method (LDM). Theoretical assumptions of LDM are, i.a. the spherical shape of the measured particles and their random orientation. These criteria are often not met. 3D prints were used to test the impact of shape on LDM PSD and to monitor particle flow with high-speed camera. It can be noticed that when the shape of the examined particles differs from a spherical shape, PSDs obtained with the use of LDM are burdened with an error that is difficult to estimate. Moreover, the more the aspect ratio value deviates from unity, the more the distribution shifts towards larger particles. It was noticed that in the case of cylinders there were no particle rotations in about 70% of cases. A lack of rotation was also observed for hemispheres-in about 16% of cases. Minimization of the errors resulting from the influence of the shape (and the related lack of rotation) of the measured particles on the obtained results may be achieved by designing the measuring cell of the diffractometer in such a way that rotation would be forced.