The technology of connecting homogeneous or heterogeneous object surfaces together through chemical or physical forces is called bonding. The materials used for bonding and adhesion are called adhesives, also known as binders or bonding agents, commonly known as glue. Because bonding can be applied to the connection of different materials, thicknesses, specifications, and complex components, and has the advantages of continuous stress distribution, light weight, simple operation, and good performance, it has developed rapidly and is widely used. It has become one of the three major connection technologies in contemporary times, including bonding, welding, and mechanical connection, and is closely related to our lives. The following will provide a detailed introduction to adhesives.

Adhesive is a substance with good adhesive properties. After curing, it has sufficient strength to firmly bond the same kind, two or more materials and parts together through surface adhesion, and at the same time can fill gaps. Adhesive is a general term that includes some other glues, mortars, pastes, and ointments. Adhesive can also be expressed as a class of natural or synthetic, organic or inorganic substances that connect two or more parts (or materials) together. Most of the adhesives we commonly see are synthetic adhesives, which are composed of a main agent and additives. The main agent is also called the main ingredient, base material, or adhesive material. It is a multi-component material that plays a basic adhesive role. In order to meet specific physical and chemical properties, various additives need to be added. Additives include curing agents, diluents, plasticizers, fillers, coupling agents, initiators, thickeners, antioxidants, polymerization inhibitors, stabilizers, complexing agents, emulsifiers, etc.
        According to requirements and uses, it can also include components such as flame retardants, foaming agents, defoamers, colorants, and fungicides. For example, in order to make the main agent form a network or three-dimensional structure to increase the cohesive strength of the adhesive layer, a hardening agent or vulcanizing agent needs to be added; in order to accelerate hardening or vulcanization, a catalyst or vulcanizing agent needs to be added; in order to reduce the stiffness of the adhesive layer and increase toughness, a plasticizer needs to be added.