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Note 1: Adhesion requires energy that can come from chemical and/or physical linkages, the latter being reversible when enough energy is applied. Note 2: In biology, adhesion reflects the behavior of cells shortly after contact to the surface. Note 3: In surgery, adhesion is used when two tissues fuse unexpectedly. [1]
Examples of permanent applications include safety labels for power equipment, foil tape for HVAC duct work, automotive interior trim assembly, and sound/vibration damping films. Some high performance permanent PSAs exhibit high adhesion values and can support kilograms of weight per square centimeter of contact area, even at elevated temperatures.
Likewise, contaminants, especially those which, due to their low surface tension, counteract wetting by the adhesive (for example, oils, release agents, etc.) hinder the adhesion interaction. Contaminants form, as it were, a barrier between the adhesive and the substrate which cannot be bridged by the adhesion forces due to their short reach.
Wood glue is an adhesive used to tightly bond pieces of wood together. Many substances have been used as glues. Traditionally animal proteins like casein from milk or collagen from animal hides and bones were boiled down to make early glues.
Common examples include mounting a workpiece to a sacrificial glue block on a lathe, and tightening pins and bolts. It is also used in conjunction with another slower, but more resilient, adhesive as a way of rapidly forming a joint, which then holds the pieces in the appropriate configuration until the second adhesive has set.
Nano tapes mimic these structures with carbon nanotube bundles, which simulate setae and individual nanotubes, which simulate spatulas, to achieve macroscopic shear adhesion and to translate the weak van der Waals interactions into high shear forces. The shear adhesion allows the tape to be easily peeled off in the manner a gecko lifts its foot.
The power of adhesion allows these organisms to be able to climb on almost any substance. [2] The exact mechanisms of arthropod adhesion are still unknown for some species, but this topic is of great importance to biologists, physicists, and engineers. [2] [3] [7] These highly specialized structures are not restricted to one particular area of ...
The two front feet of a tokay gecko can withstand 20.1 N of force parallel to the surface with 227 mm 2 of pad area, [4] a force as much as 40 times the gecko's weight. . Scientists have been investigating the secret of this extraordinary adhesion ever since the 19th century, and at least seven possible mechanisms for gecko adhesion have been discussed over the past 17