Adhesive adhesion theory

The theory of adhesive adhesion is a set of scientific principles and assumptions that explain how adhesives can bond different materials together. Here is a brief explanation of each of these theories:

1. Physical absorption theory

This theory focuses on van der Waals forces. Van der Waals forces include attractions between permanent dipoles, induced dipoles, and Landen forces. These forces create a strong connection between the adhesive and the desired surface. These types of bonds are often seen in general adhesives and simple applications.

2. Chemical adsorption theory

According to this theory, covalent, ionic and hydrogen bonds play a major role in creating adhesion. These bonds provide high structural stability. For example, hydroxide or amine groups in adhesives cause hydrogen bonds with materials such as wood, which themselves have hydroxyl groups.

3. Glue penetration theory

This theory states that adhesion is caused by the penetration of adhesive polymers on the surface of another material. If two polymers have high compatibility, they can penetrate into the anchor regions after mixing. The molecular weight of the polymer is also influential in this process.

4. Electrostatic theory

This theory is based on creating an electrical double layer between two metals with an insulating material between them. This layer is formed due to opposite electric charges on different planes and forms a strong bond.

5. Theory of internal mechanical linkage

This theory explains that the adhesion is due to the penetration of the adhesive into the unevenness of the surface of the desired material. The surface of the material actually has roughness and pores in which the glue penetrates and creates a bond. A simple example of this theory is in sewing and the use of adhesive layer in fabric.

6. Weak boundary layer theory

This theory states that the presence of surface contaminants such as paint, oil, and grease can cause weaker bonds. But in some cases, these weak bonds can also be useful and should be used according to the specific application of the adhesive.

Conclusion

Each of these theories suggests that adhesion is a multidimensional and complex process that cannot be attributed to just one specific cause. Choosing the right theory depends on the type of material and the specific application of the adhesive.