Metals
After surface treatment, the oxide film on metal surfaces can be easily bonded. However, due to the significant difference in linear expansion coefficients between the two phases (metal and adhesive), internal stress is prone to occur in the adhesive layer. Additionally, the bonded parts of metals are susceptible to electrochemical corrosion when exposed to water.
Rubbers
The higher the polarity of the rubber, the better the bonding effect. Among them, nitrile rubber and neoprene have high polarity and strong bonding strength; natural rubber, silicone rubber, and isobutylene rubber have low polarity and weak adhesion. In addition, rubber surfaces often have mold release agents or other free additives that hinder the bonding effect.
Wood
As a porous material, wood is prone to moisture absorption, which causes dimensional changes and may lead to stress concentration. Furthermore, polished wood exhibits better bonding performance than rough-surfaced wood.
Plastics
Plastics with high polarity have good bonding performance.
Glass
Microscopically, the glass surface consists of numerous uneven and non-uniform protrusions and depressions. Moreover, glass has a main structure of Si-O-, and its surface layer easily absorbs water. Due to glass's strong polarity, polar adhesives can readily form hydrogen bonds with the surface, achieving firm bonding.