Wettable powder formulations tensions

If a suspension is to be produced by a dispersion technique (as opposed to precipitation techniques), surfactants may be used in the formulation to aid dispersion of the solid particles in the liquid. This is particularly important if the powder is not readily wetted by the liquid vehicle. Surfactants can reduce the interfacial tension between the solid particles and the liquid vehicle. The advancing contact angle is reduced, and wetting of the solid particles promoted. Such a system is said to be deflocculated. The inclusion of a surface-active agent to improve powder wettability can often improve the bioavailability of the formulation. 

If little growth is desired, granulation may be halted early in growth, or limited to nucleation. If the formulation is wettable by the binding fluid, this is best achieved in the drop-controlled regime of nucleation, which requires fast drop penetration and low spray flux [Eq. (21-107)], Fig. 21-107). Small drop penetration time fp is possible for low binder viscosity, high adhesion tension, coarse feed powders, and... 

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