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Capillary adhesion

The paper by Tliompson [15] should be mentioned as pointing out the importance of the capillary adhesion which can be Uie major factor responsible for.the caking phenomenon narrow layer of tlie saturated solution between the particles shows a lowered meniscus of the solution, i.c. reduced pressure. Consequently the action of atmospheric pressure becomes sufficiently strong to compress the neigltbouring granules into a solid block,... [Pg.231]

Adhesive contacts (capillary adhesion) are formed as a result of molecular attraction between the surfaces in contact [76,77]. The forces of attraction involved in this phenomenon, known as Van der Waals forces, are considered to be relatively weak. This type of contact is influenced mostly by the plasticity of the particles and the pressure exerted on the fertilizer material when it is stacked in bags or piled in bulk, usually referred to as bag or pile set. The material normally reverts to a free-flowing form rather easily with a minimal amount of handling. [Pg.487]

Hydrophobic siloxane monolayers are effective at preventing capillary adhesion in MEMS operating in ambient air. However, the use of SAMs to prevent stiction in harsh environments (elevated temperature or fluids) has been investigated to a lesser extent. Packaging or specific application conditions can expose MEMS to elevated temperatures. Similarly, the advent of bioMEMS and microfluidic devices opens the door to a wide range of applications in liquid environments. [Pg.57]

This section draws on the work of Laplace published in 1805. Surface tension is at the origin of the overpressure existing in the interior of drops and bubbles. This pressure difference has multiple consequences. For instance, smaller drops will disappear in favor of larger ones in an emulsion, and they will be the first to evaporate during the cooling phase of an aerosol. The pressure difference also explains the phenomenon of capillary adhesion between two plates, between hairs or fibers, or in wet sand, all of which are induced by capillary bridges. [Pg.6]

FIGURE 1.8. Capillary adhesion of two plates with a drop squeezed in-between. [Pg.9]

It is thus evident that, within a first approximation. Equation 1.30 is valid for both wetting and nonwetting liquids, with a meniscus either present or absent. It is, however, worth pointing out that for macroscopic particles, this is valid only in the case of molecularly smooth surfaces. In this case, the equations for the molecular adhesive forces and for the capillary contraction force both contain the same macroscopic value of R. The situation is different for rough surfaces. Namely, the value of R in the expression for the molecular forces may be determined by the radii of microheterogeneities between which the contact is formed, while the value of R in the expression for the capillary adhesion force may be determined by the macroscopic radii of the particles. Consequently, particles with a microscopically... [Pg.23]

Capillary adhesion forces influence of relative humidity... [Pg.320]

M. Kober, E. Sahagun, P Garcia-Mochales, E Briones, M. Luna, and J. J. Saenz, Nanogeometry matters unexpected decrease of capillary adhesion forces with increasing relative humidity. Small, 6, 2725-2730 (2010). [Pg.357]

Such investigations implicated intermolecular forces but did not allow for capillary adhesion and van der Waals forces to be distinguished from each other. Van der Waals interactions are the most universal and also the weakest of the intermolecular forces. [Pg.107]

A subsequent set of experiments expanding upon Hiller s findings, were conducted in order to ascertain the type of force primarily responsible for adhesion in gekkotans. The inability of geckos to stick to hydrophobic, weakly polarizable surfaces (those with a high water contact angle) could have been due to either reduced capillary adhesion or reduced van der Waals forces. In order to resolve this problem, polarizability was separated from hydrophilicity/hydrophobicity. This is important because van der Waals adhesion depends on the creation of instantaneous dipoles, and... [Pg.108]

One may also be able to determine the work of adhesion for cases in which the contact angle is zero by using probe liquids, as described later in this chapter. There are also other ways of determining the work of adhesion, such as inverse gas chromatography, which do not depend solely on capillary measurements (surface tension and contact angle). This too will be discussed later. [Pg.10]

Still another area where chemical and physical interactions can occur involves the enhancement of particle adhesion due to capillary condensation [69]. However, for the purposes of the present discussion, let us limit ourselves to dry particles. [Pg.161]

An example of interaction stiffness and force curves for a Si surface with a native oxide at 60% relative humidity (RH) is shown in Fig. 12 [104]. The stiffness and force data show an adhesive interaction between the tip and substrate. The hysteresis on retraction is due to a real change in contact area from surface oxide deformation and is not an experimental artifact. The adhesive force observed during retraction was consistent with capillary condensation and the surface energy measured from the adhesive force was close to that of water. [Pg.210]

There are a number of tissue adhesives currently approved as adjuncts to hemostasis. Each agent has specific properties which enhance intraoperative hemostasis in particular situations. All forms of surgical bleeding are not alike. Bleeding can be fast or slow, diffuse or punctate, arterial or venous, capillary or larger vessel. Thus one agent may be more efficacious than another in a specific clinical situation. [Pg.1112]

Solid bed dehydration systems work on the principle of adsorption. Adsorption involves a form of adhesion between the surface of the solid desiccant and the water vapor in the gas. The water forms an extremely thin film that is held to the desiccant surface by forces of attraction, but there is no chemical reaction. The desiccant is a solid, granulated drying or dehydrating medium with an extremely large effective surface area per unit weight because of a multitude of microscopic pores and capillary... [Pg.228]


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See also in sourсe #XX -- [ Pg.299 ]

See also in sourсe #XX -- [ Pg.107 ]




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Adhesion capillary condensation

Adhesives capillary-flow

Applications capillary-flow underfill adhesives

Capillary-flow underfill adhesives

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