Adhesion forces of a liquid bridge

The maximum tensile force that can be transmitted by a liquid bridge between two monosized spheres consists of two components  

An adhesion force component A caused by the negative pressure / c in the bridge  

An adhesion force component A y caused by the boundary force at the solid-liquid-gaseous contact line, which is determined by the surface tension of the liquid ot  

By adding the two parallel adhesion force components A and A and after introducing the dimensionless function //a, a formula for the effective adhesion force 4l of a liquid bridge is obtained  

Therefore, the adhesion force of a liquid bridge is proportional to the surface tension a, the particle diameter x, and a function of the angle the angle of contact 6, and the dimensionless quotient a/x, /3 defines the size of the liquid bridge and can be substituted by / , the liquid volume divided by the volume of the solid particles  

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Work of many researchers concentrates on modelling and calculating adhesion forces that are caused by the different binding mechanisms [B.42]. So far, all models are based on simplified conditions at the coordination points. For example, modelling of the adhesion force of a liquid bridge is based on two monosized spherical particles with a distance a from each other (Fig. 5.20). 

These data indicate that particle adhesion in vacuum is less than in air water vapor increases the adhesive force there are no capillary forces when the particles are under vacuum, while in air these forces are manifested upon the appearance of a liquid bridge in the gap between the contiguous bodies in an atmo-... 

Figure 9.5 schematically shows the capillary effect and the resulting effect on the particle adhesion. A liquid bridge forms between the particle and the substrate and holds the particle to the surface by surface tension. The liquid film could be a result of capillary condensation in high relative humidity or of a retention of liquid during substrate removal from the liquid bath. The attractive force is composed of the force caused by surface ten-... 

Adhesion between the filaments of a yarn is an important requirement in processing of hbers. Twist contributes significantly to yarn cohesion. In the case of low-twist continuous filament yarns, filament adhesion can be improved considerably by the application of a liquid finish. Liquid bridges are formed by the applied finish, and the capillary pressure of these liquid bridges is responsible for the increase in cohesion. This is shown schematically in Figure 5 (47). The force per unit length of the fibers is given by... 

Capillary forces develop when liquid bridges are formed in small gaps between two surfaces. Above a critical relative humidity, capillary forces are the dominant attractive force between aerosol particles [269,270]. The magnitude of this force depends on other parameters as well, such as particle surface chemistry and size. For two particles attached by a liquid bridge, the adhesive force is [260] ... 

Figure 4.8 Dimensionless adhesion force of liquid bridges as a function of liquor volume [Rumpt 1977]...

The two most easily distinguishable forces of attraction are suction and liquid bridge adhesion. The suction pad, as explained in Fig. 2.5, relies on atmospheric pressure to hold the bodies together. This pressure remains constant as the pad is pulled away from its substrate. The same is true of a liquid droplet acting to glue two balls together the force of adhesion is constant as the balls separate, as shown schematically in Fig. 2.12. Thus these two types of adhesion... 

Several times in this section liquid bridges have been encountered, i.e. bodies of fluid with concave surfaces, connecting a solid object and a fluid. In connection with flg. 5.46 we shall briefly address these. In particular such bridges play important roles in the adhesion between two solid macrobodies, say between the particles in a powder. Depending on conditions, the Laplace underpressure in the bridge may result in a stronger adhesive force than that caused by Van der Waals forces. 

Fig. 5.4 Random cut through part of an agglomerate or a particulate bulk solid mass and explanations of how strength may be caused, (a) Pore volume filled with a matrix binder, (b) Pore volume filled with a wetting liquid, (c) Liquid bridges at the coordination points, (d) Adhesion forces at the coordination points.

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