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Chemical adhesion occurs when the surface atoms of two separate surfaces form ionic, covalent, or hydrogen bonds. The engineering principle behind chemical adhesion in this sense is fairly straightforward: if surface molecules can bond, then the surfaces will be bonded together by a network of these bonds.
Textures create an uneven surface which will make it harder for the adhesives to be in contact with the surface thus lowers its wetting ability. [15] Water or moisture of any form will reduce surface adhesion and reduce tape tackiness. Moisture can be removed off the surface by any physical methods or chemical methods too.
Pre-treatment can be used to modify surfaces in a targeted way and thus make them more adhesive. [3] In addition to coating the substrates with an adhesion promoter to enable good adhesion, surfaces can also be modified by various methods to prepare them for gluing. The most common surface pre-treatment methods are listed in the adjacent figure.
Some removable adhesives are designed to repeatedly stick and unstick. They have low adhesion and generally cannot support much weight. Sometimes clean removal of pressure sensitive tape can be difficult without damaging the substrate that it is adhered to. Pulling at a slow rate and with a low angle of peel helps reduce surface damage.
Dispersive adhesion, also called adsorptive adhesion, is a mechanism for adhesion which attributes attractive forces between two materials to intermolecular interactions between molecules of each material. This mechanism is widely viewed as the most important of the five mechanisms of adhesion due to its presence in every type of adhesive ...
Adhesion, the attachment between adhesive and substrate may occur either by mechanical means, in which the adhesive works its way into small pores of the substrate, or by one of several chemical mechanisms. The strength of adhesion depends on many factors, including the means by which it occurs.
In order to reach chemical equilibrium, the process of diffusion will take place which will increase any measurement of the work of separation. [2] The work of adhesion is the reversible free energy change for making free surfaces from interfaces. [2] It is represented by the equation:
In adhesion tests per ASTM D4541, in which an aluminum stud is bonded to the test surface and the stud is pulled in the direction normal to the surface, both surfaces of the failure interface were analyzed by X-ray photoelectron spectroscopy (XPS). F/C ratio was used as an indicator of the failure mode: F/C of zero corresponds to failure in the ...