X. Pepin et al., Hardness of moist agglomerates in relation to interparticle friction, granule liquid content and nature, POWD TECH, 117(1-2), 2001, pp. 123-138
Wet agglomerates deform plastically until they break through crack propagat
ion. On the particulate level, liquid bridges are responsible for the stren
gth of the wet agglomerate as they hold the particles together. The experim
ents reported in this paper identify the role of liquid surface tension, br
idge Laplace pressure and liquid viscosity, which, in combination, explain
the axial strength of pendular liquid bridges. Different situations exist d
epending on the degree the liquid wets the particles, and on the saturation
of the agglomerate mass. A parabolic approximation can be used to describe
the shapes adopted by pendular liquid bridges.
On the wet agglomerate level, the hardness is related to three factors: the
liquid binder surface tension and viscosity and the interparticle friction
. A simple model is developed in this paper, based on the powder and liquid
binder properties, which shows that the forces due to interparticle fricti
on are generally predominant in wet agglomerates made from non-spherical pa
rticles. Although mechanical interlocking is not predicted, this model yiel
ds accurate prediction of wet agglomerate hardness independently measured o
n wet masses of varying composition. This theoretical hardness could prove
an interesting tool for wet granulation research and technology. (C) 2001 E
lsevier Science B.V. All rights reserved.