When two materials are adhered to each other with an adhesive, such as glue or epoxy, an adhesive bond is formed. Depending on the type of substance used, different methods can be used to create the bond. Adhesive bonding has a wide range of uses and has several advantages over other fastening methods. It also has some drawbacks, such as irreversibility and the requirement for drying time under ideal conditions.
During adhesion, several different microscale forces interact. The adhesive bond is mechanical when surfaces physically interlock with one another. When two substances form a chemical bond, chemical adhesion is at work. Dispersive adhesion is caused by Van der Waals forces, which are attraction between molecules with opposite charge areas. This interaction allows a car decal to adhere to smooth glass without the use of chemical adhesives.
The majority of adhesives used today are synthetic polymers, which are organic molecules made up of long chains of carbon and hydrogen units. Epoxy is made up of two polymers: one is a resin, and the other is a hardener. When these two polymers interact, they form a strong chemical bond. Chemical adhesion forms an adhesive bond as a result of the attraction.
Solvent-based adhesives, such as white glue and rubber cement, are another type of glue. Polymers dissolved in a solvent make up these substances. The solvent evaporates in the air, leaving the polymers behind, which solidify. In an adhesive bond, a layer of hardened glue binds the two materials together.
Adhesives have become widely used in the construction industry as a result of the development of glues and epoxies capable of forming strong adhesive bonds. Unlike nails and screws, adhesives spread evenly across the joined area, distributing stress evenly. They are also lighter than metal fixtures and form a seal that helps prevent corrosion by joining materials together invisibly. Adhesives are also versatile, as they can be used to join almost any two materials, even those with irregular shapes.
Adhesives, despite their benefits, have limitations. The curing, or hardening, time is one disadvantage: substrates must be prepared and supported while the adhesive bond forms. Temperature and moisture must be kept under control during this time. Even after it has hardened, if the bond is exposed to excessive heat or chemical substances that can dissolve it, it may fail structurally. Problems with glued joints are also difficult to diagnose because they cannot be disassembled without breaking apart. As a result, the durability of certain types of adhesive bonding poses a problem for construction projects.