Metals
After surface treatment, the oxide film on metal surfaces can be easily bonded. However, due to the large difference in linear expansion coefficients between the two phases when adhesives bond metals, internal stress is likely to occur in the adhesive layer. In addition, the bonded parts of metals are prone to electrochemical corrosion due to the action of water.
Rubbers
The greater the polarity of rubber, the better the bonding effect. Among them, nitrile rubber and chloroprene rubber have high polarity and high bonding strength; natural rubber, silicone rubber, and isobutylene rubber have low polarity and relatively weak bonding force. In addition, rubber surfaces often have release agents or other free additives, which 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. Moreover, polished wood has better bonding performance than rough-surfaced wood.
Plastics
Plastics with high polarity have good bonding performance.
