Surface treatment prior to adhesive bonding

1. Before bonding, the surfaces of construction components often harbor contaminants such as oil, mold release agents, weathered layers, carbonized layers, and rust. Failure to remove these unclean or structurally unsound surface layers can significantly impair bonding performance.
2. Roughening the surface of the adherend increases the actual bonding area; for instance, sandblasting can increase the effective bonding area of ​​a polished metal surface by twenty-fold. Furthermore, a rough surface allows the cured adhesive to form more interlocking structures—creating mechanical interlocking forces—thereby enhancing bond strength. This has been confirmed by both theory and practical experience.
3. Surface treatment can also improve surface properties. Chemical treatment of metal surfaces, for example, can modify surface tension, thereby increasing bond strength. Certain low-energy plastics and rubbers that are difficult to bond require surface treatment to achieve effective adhesion (such as treating PTFE with a sodium-naphthalene solution). Additionally, the aforementioned coupling agents can enhance bonding performance during surface treatment; thus, surface treatment plays a crucial role in construction bonding processes.