Effect of Particle Characteristics on Packing Structure

Abstract

The effects of the particle-shape (which is irregular, rod-like or spherical) and the ratio of interparticle-cohesion/particle-weight on the initial fractional voidage before tapping, the rate of tapping-compaction and the final fractional voidage attained by tapping were studied. The samples were monodispersed powders with their sizes ranging from 12 to 127 (a. A good correlation was found between the initial fractional voidage and Fo/ppdp3 except for the rod-like particles. The initial fractional voidage of the rod-like particles is much greater than that of the irregular or spherical ones, which is explained in terms of the strong mechanical resistance caused by interlocking of particles due to the high elongation of the rod-like particles. In the dense packing the structural resistance is more pronounced than in the loose packing and, moreover, in the dense packing the effect of the compacting-force must be taken into account in the calculation of the interparticle cohesion. The rate of tapping-compaction suffers from little influence of the particle-shape. The physical meanings of the correlations which have been found empirically between the angle of repose and e0or A V could be elucidated to some extent through the relations between each of them and Fojppdp. © 1973, The Pharmaceutical Society of Japan. All rights reserved.