Introduction - adhesion theories

Adhesion can be either wanted (paints, glues, etc.) or not (biofouling, cleaning, etc.). In either case, studies should ensure at first good wetting and also estimation of the theoretical work of adhesion via use of an interfacial theory, e.g. Owens-Wendt or van Oss-Good. 

There is little doubt that adhesion is a mystery and understanding adhesion is closely related to the understanding of not just wetting phenomena but numerous more aspects. Today, adhesion control is often done largely empirically and is considered to be a combination of art and science, often learned via training and practice. However, theoretical considerations may be of help in explaining especially the problems that may appear and suggest solutions. 

In somewhat more detail, the following steps can be included in adhesion studies  

Adhesion forces are, in most cases, short-range ones like van der Waals t5qje and hydrogen bonding. For such forces to apply, the two surfaces, e.g. a liquid and the sohd, must be in very close (intimate) contact (adhesion forces apply at distances less than 10 nm). Thus, very good wetting is almost always a 

Thermodynamic adsorption is the most general theory and the only explanation in the absence of, for example, chemical promoters, high mobility of polymeric chain and porosity. It should be emphasized that the van der Waals (dispersion) forces between particles/surfaces, which are involved, are not as short range as those between molecules they decrease with the third power of the distance (not the seventh power). Adhesive forces are discussed next (Section 6.3.2). 

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Introduction and Adhesion Theories Table 1.1 Theories of Adhesion... 

The significance in contemporary adhesion theory of Lewis acid-base interactions has been discussed in Acid-base interactions introduction. It was argued that in many... 

Though the Russian school has been credited with the introduction of the EDL electronic adhesion theory,O07) the idea of donor-acceptor (or acid-base) interaction did not originate from their school. 

This chapter has been adapted from Introduction and Adhesion Theories in Adhesives Technology Handbook ed.), Ebnesajjad 2008 Elsevier Inc. 

TTie theory of heterogeneous phase formation is well developed fi-om the viewpoint of classical thermodynamics. A significant turning point seems to be the introduction of the adhesion energy and an appreciation of its influence on the form and energy of formation of crystals on foreign substrates. 

The introduction to the concept of static and kinetic friction in Chapter 7, Section 2 is admittedly simplistic. Familiarity with the experimental details of measuring friction leads to a more realistic view in behavioristic terms and also to some theoretical questions. In particular, the theory of stick-slip friction requires that be greater than and distinct from and indeed Fig. 7-5a shows a discontinuity between static and kinetic friction. But the model for the fundamental adhesive mechanism of friction does not predict such a discontinuity. 

The chemisorption theory was probed by monitoring the changes in the surface chemistry of the PP and PET due to CDT. The introduction to the surface of the plastic films of any functional groups that could interact with the silicone coating would imply that chemical adsorption was an important mechanism of adhesion. 

Theories of adhesion K W ALLEN General introduction to mechanical, adsorption, diffusion and electrostatic theories... 

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