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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.
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.
Adsorption is the adhesion of ions or molecules onto the surface of another phase. [1] Adsorption may occur via physisorption and chemisorption. Ions and molecules can adsorb to many types of surfaces including polymer surfaces. A polymer is a large molecule composed of repeating subunits bound together by covalent bonds. In dilute solution ...
For a peel ply, a thin, woven piece of material is applied to the adherend during fabrication. [9] Because the material is woven, it will leave a torturous surface when removed, which will improve bonding by mechanical interlocking. [6] Prior to adhesive bonding, the woven material acts to protect the surface of the adherend from contaminates.
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.
Mucoadhesion involves several types of bonding mechanisms, and it is the interaction between each process that allows for the adhesive process. The major categories are wetting theory, adsorption theory, diffusion theory, electrostatic theory, and fracture theory. [5]
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.
The adhesion is a result of the chemical components of the activator softening the base coat layer and allowing the ink to form a bond with it. One of the most common causes of a failure to achieve adhesion between the two layers is a poorly applied activator. This can be either too much activator being applied or too little. [9]