What is the mechanism of bringing two similar or dissimilar materials together? Below are five commonly discussed adhesion mechanisms.

1. Physical Adsorption
2. Chemical Reaction
3. Inter-diffusion
4. Electrostatic Attraction
5. Mechanical Interlocking

Physical Adsorption:
All materials have different polarities resulting from the density of electron clouds surrounding their chemical element or functional group. The magnitude of force attributed from these electron clouds, from low to high forces are Van der Waals force, dipole-dipole moment, hydrogen bonding, and acid-base interaction. The greater force is the spit of electron clouds or polarity difference; the better force is the attraction force when two materials are brought together. In general, polar substrates and adhesive offer higher polarity and cause higher adhesion forces… Read Article>>

Principles of Pressure Sensitive Adhesion
- by Pierce Covert, Glue Machinery Corporation