(1) Metal: After the oxide film on the metal surface is treated, it is easy to be bonded; because the linear expansion coefficients of the two phases of the adhesive bonding the metal differ greatly, the adhesive layer is prone to internal stress; in addition, the bonded part of the metal is likely to undergo electrochemical corrosion due to the action of water.
(2) Rubber: The greater the polarity of the rubber, the better the bonding effect. Among them, nitrile rubber and chloroprene rubber have high polarity and strong bonding strength; natural rubber, silicone rubber and butyl rubber have low polarity and weak adhesive force. In addition, the rubber surface often has a release agent or other free additives, which will interfere with the bonding effect.
(3) Wood: It is a porous material and is prone to moisture absorption, which causes dimensional changes and may lead to stress concentration as a result. In addition, polished materials have better bonding performance than rough-surfaced wood.
(4) Plastic: Plastics with high polarity have good bonding performance.
(5) Glass: From a microscopic perspective, the glass surface is composed of countless uneven and rough parts. Use an adhesive with good wettability to prevent the possible presence of air bubbles in the uneven parts from affecting the bonding. In addition, glass has a main structure of Si-O-. Its surface layer is easy to adsorb water. Due to the strong polarity of glass, polar adhesives are likely to form hydrogen bonds with the surface and form a firm bond. Glass is brittle and transparent, so these characteristics need to be considered when selecting an adhesive.