Generally speaking, the materials that adhesives can bond can be divided into five major categories.
1. Metal
The oxide film on the metal surface is easy to bond after surface treatment; because the two-phase linear expansion coefficient of the adhesive bonding the metal is too different, the adhesive layer is prone to internal stress; in addition, the metal bonding part is prone to 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 chloroprene rubber has high polarity and high bonding strength; natural rubber, silicone rubber and isobutadiene rubber have low polarity and weak bonding force. In addition, there are often release agents or other free additives on the rubber surface, which hinder the bonding effect.

3. Wood
It is a porous material that easily absorbs moisture, causing dimensional changes, which may cause stress concentration. In addition, polished materials bond better than wood with rough surfaces.

4. Plastic
Plastics with high polarity have good bonding properties.

5. Glass
From a microscopic perspective, the glass surface is composed of countless uniform uneven parts. Use an adhesive with good wettability to prevent possible bubbles in the concave and convex areas. In addition, glass has si-o- as its main structure, and its surface layer easily absorbs water. Because glass is highly polar, polar adhesives can easily hydrogen bond with the surface to form a strong bond. Glass is brittle and transparent, so take these into consideration when choosing an adhesive.

PP material is a non-polar material with low surface energy. When performing the gluing process on the surface of PP material, it is easy to have problems such as degumming due to poor bonding between the substrate and the glue. Coating Online tells you an effective solution is to Effective pre-treatment of the PP material surface. In addition to basic cleaning, use PP treatment agent to brush between the substrate and the glue to enhance the bonding force and solve the problem of degumming.