Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. Adhesives can be categorized in different ways, according to their chemical composition, physical form, classification, or load-bearing capability. Some of the most common types of adhesives include:
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Epoxy adhesives: These are a type of structural adhesive that is highly temperature and solvent resistant and can be structurally bonded to most types of materials, such as metals, ceramics, wood, and plastics.
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Polyurethane adhesives: These are polymer-based adhesives used for constructions requiring high strength bonding and permanent elasticity. They are often offered as two-part adhesives and have many uses.
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Cyanoacrylate adhesives: These are fast-acting adhesives that bond quickly and strongly to a variety of surfaces, including metal, plastic, and rubber.
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Acrylic adhesives: These are versatile adhesives that can bond a wide range of materials, including metal, plastic, and glass.
The use of adhesives offers certain advantages over other binding techniques such as sewing, mechanical fastenings, or welding. These include the ability to bind different materials together, the more efficient distribution of stress across a joint, the cost-effectiveness of an easily mechanized process, and greater flexibility in design. However, disadvantages of adhesive use include decreased stability at high temperatures, relative weakness in bonding large objects with a small bonding surface area, and greater difficulty in separating objects during testing.
