Solid state capillary force

The 1987 Montreal protocol (4) initially limited the use of CFC propellants and then banned them by 2009 in the United States (51). In addition, degradation kinetics of therapeutic biomolecules is slower in the solid state than in the liquid state. Combined with bypassing the first-pass effect of hepatic metabolism and drug degradation in the gastrointestinal tract, the lungs have been an attractive route of administration of sensitive biomacromolecules in the solid state. The forces of interaction between particles present barriers to their flow and dispersion. The major forces of interaction are van der Waals, electrostatic, and capillary forces (52). 

Chocolate is not only delicious, but has remarkable mechanical properties. In the solid state, it can be cold-extruded"—that is, forced to flow tluough a capillary die... 

The preceding discussion was concerned with capillary forces in a system containing only the liquid of interest and a second fluid phase. It has been stated, however, that the systems of most practical interest involve a third phase (usually a solid) resulting in a three-phase boundary line. The situation can be represented as a drop of liquid resting on a flat solid surface and... 

If a thin wet film of emulsion adhesive is applied between two porous surfaces and these three components subjected to an adequate degree of compression, the initial state of the adhesive is one of a water phase containing discrete and stable polymer particles. Wetting of the substrate surfaces then takes place followed by the commencement of penetration of the water phase into the substrates (see Wetting and spreading). As this occurs, the solid content of the adhesive film rises and it becomes more viscous and tacky. Capillary forces in the substrate then continue to draw water (and, dependent on substrate porosity, possibly some polymer solids) from the adhesive until its solid content rises to the point where it coalesces into a continuous film. 

In the solid state, the capillary force can be expressed as an increase or decrease in chemical potential of a species in the vicinity of a curved interface relative to a... 

Mastrangelo CH, Hsu CH (1993) Mechanical stability and adhesion of microstructures under capillary forces - part I basic theory. J Microelectromech Syst 2(l) 33-43 Mulhem GT, Soane DS, Howe RT (1993) Supercritical carbon dioxide drying of microstructures. In Technical digest 7th international conference on solid-state sensors and actuators (Transducers 93), Yokohama, p 296... 

Consider now the dynamical deposition of a film caused by a relative motion between the solid and the liquid (Figure 5.11). For low capillary numbers, the thickness of the film results from a compromise similar to the one we have described in the context of a plate. Specifically, the viscous force in the meniscus is balanced out by the capillary force which tends to bring the liquid back into the reservoir. Remarkably, in both geometries considered here, the expression giving the Laplace pressure difference between the film and the reservoir takes on the same form when the thickness is small. In this limit, the film turns out to be in state of overpressure by an amount j/b with respect to the reservoir. 

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