Stickiness of glue
Typically, even a thin film of liquid glue between two hard surfaces has a certain final thickness. The distance between the surfaces excludes the possibility of mutual attraction of the molecules of these surfaces or even their contact.
It is difficult to assume that adhesive forces are able to act through the film of glue; Rather, they act only on the surface of the section between glue and the glued surface. It is also unlikely that the effect of molecular attraction of the solid surface stretches over a greater distance than the thickness of the monomolecular layer of liquid glue. Therefore, the strength of the adhesive compound is determined primarily by the properties of the glue.
The adhesiveness of the glue counteracts a relative displacement of glued materials in perpendicular and tangentral directions if these movements are not too slow. Therefore, the ability to stick fluid to counteract relative displacement of surfaces is a general requirement for adhesives.
If not too large disconnecting forces are attached to the glued surfaces and if the application time of these forces is not too much, then destruction does not occur, since liquid glue shows the flow resistance, as well as a shift and deformation, thus counteracting the disconnecting forces and balancing them.
Very often stickiness is characterized by dacticity, t. e. the ability of adhesives to stretch into long threads. Therefore, oral adhesives do not have a limit limit, but highly viscous adhesives are able to stretch into long threads.
Suggest that long threads provide greater bonding strength than short. The presence of the fluidity of low -producting adhesives prevents their intensive penetration into the pores of glued materials. This can be the cause of the higher strength of the oxide adhesives, the moderate penetration of which favors the production of glued materials into the pores of the glued adhesive compound. In addition, the adhesive strength of the oxide adhesives contributes to their high viscosity. The initial stickiness of low -producting adhesives is greater than in oral.