24 августа, 2015 
Pokraskin Although, to date, the phenomenon of adhesion in bonded joints has not yet
been completely explained by means of scientific concepts, our existing knowledge
allows some simple conclusions to be drawn that are of considerable technical
importance:
• The wetting of adherent surfaces by the adhesive is an important — but insufficient — prerequisite for the build-up of adhesion. Wetting experiments may provide the first indications with regards to the bonding characteristics of a surface and its polarity, the latter referring to the quality ofadhesion. However, it is not possible to determine the exact characteristics of adhesion by means of wetting measurements.
• In addition to physical interactions, it is particularly desirable to have adhesives (especially reactive adhesives) build up chemical interactions with the adherent surfaces in order to obtain good adhesion. The formation ofchemical interactions maybe enhanced by surface pretreatment, the use ofadhesion promoters, and with specific formulations of adhesives.
• Chemical interactions modify the nature of the adhesive and the adherent surfaces, respectively, near the interface. This may have positive effects on the water resistance of adhesive assemblies, for example by the stabilization of metal oxides as a result of chemical reactions, or by modification ofthe polymer dynamics within the adhesive near the interface.
• Adhesion hardly ever fails where it has developed. Invariably, so-called ‘adhesion failure’ will actually occur within the adherent or the adhesive near the interface — an area which will have been influenced by the build-up of adhesion.
• In practical terms, the microscopic roughness of the adherent surface does not have any influence on the quality of adhesion.
• Nanostructures or nanomorphologies on the adherents may improve the quality of adhesion, although the reasons for this are not yet known.
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