Capillary cohesion phenomenon

Capillary cohesion phenomenon — Kelvin equation. The theory of capillary cohesion and Kelvin equation are the theoretical basis of physical vapor adsorption. When the steam of adsorbate contacts with porous solid surface, it will form liquid film of the adsorbate on the surface adsorption field. The films in the pore bend variously with the pore diameter, while the films in the outer surface of particles are relatively flat. The film thickness of liquid of adsorption increases with increase in vapor pressure. When it reaches a certain moment, the gravity between the curved liquid surfaces sufficiently liquidity the vapor from gaseous automatically, and completely fill the pores. This phenomenon is known as capillary cohesion. 

An important historic development was the insight that surface tension is a surface- and not a bulk-property. Newton ) had already discriminated between cohesive and adhesive forces. A decisive discriminative experiment was carried out by Hawksbee ). He investigated liquid rise in capillaries and between glass plates and found that the thickness of the glass did not matter. So the phenomenon of wetting was established as a surface phenomenon, although the depth of the interactions responsible for the various tensions still remains an issue today (chapter 2). 

The magnitude of surface tension, y, is determined by the internal forces in the liquid thus it will be related to the internal energy or cohesive energy. The surface tension or the capillary phenomenon was mentioned in the literature at a very early stage by Leonardo da Vinci. 

From the relation L=f(vij) it is obvious that the spinnability is governed by two processes, namely the cohesive break (or the swell effect) and the melt break (capillary break, melt fracture). According to Section 11.3.1, a certain amount of elastic energy can be stored in all viscoelastic fluids. This phenomenon leads, among others, to the Barus effect. 

Liquids also exhibit a phenomenon called capillary action, the spontaneous rising of a liquid in a narrow tube. This action results from the cohesive forces within the liquid and the adhesive forces between the liquid and the walls of the container. If the forces between the liquid and the container are greater than those within the liquid itself, the liquid will climb the walls of the container. For example, consider the California sequoia, a tree that reaches over 200 feet in height. Although water rises only 33 feet in a glass tube (under atmospheric pressure), capillary action causes water to rise from the sequoia s roots to all its parts. 

Theory The release under shear of an active molecule that is initially encapsulated in the aqueous phase of a W/OAV multiple emulsion is a very promising phenomenon for applications in cosmetics or pharmaceuticals. Taylor (Taylor, 1932, 1934) was first to study the deformation of molecules under shear and their bursting in a simple, dilute emulsion. He considered that breakup occurred when shear stress exceeds cohesion stress. He defined this breakup by way of a capillary number, Ca ... 

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