‘Van der Waals’ forces may play a role in building up structural integrity in the pellet
when particles are sufficiently small ( < 50 pm, de Jong, 1995; < 60 km, Rumpf, 1958
and Friedrich, 1964b). In general, in animal feeds the fraction of these particles is too
negligibly small to substantially increase binding strength in pellets. When particle size
increases, the effect of ‘Van der Waals’ forces diminishes and other binding mechanisms
(capillary forces and binder materials) become more pronounced.