Chemicals & Adhesives
Adhesives come in many types, classified according to base, viscosity, setting speed, strength and temperature range. Adhesives are based on epoxy, cyanoacrylate, methacrylate, starch or synthetic elastomers. Cyanoacrylates are a class of compounds with quick setting properties and short shelf life. Super Glue, widely used in homes and offices for bonding purposes, is the most well-known cyanoacrylate-based adhesive. Methacrylate adhesives have better hydrolytic stability and cure with the help of catalysts, in contrast to cyanoacrylates that cure in moist air. Epoxy-based adhesives bind by setting or hardening, and the curing often has to be aided by elevated temperatures. Epoxies have a wide range of shear strength, hardness and curing time, and may be mixed with additives such as sawdust, fiberglass bits or glass bits, to alter their properties. Common applications of epoxies are to fill gaps or fix structural joints, and in plumbing. Synthetic elastomers are used in making spray adhesives. Application of adhesives, especially for commercial and industrial purposes, requires accessories, such as mixing nozzles and plungers. Industrial application of adhesives is often done with adhesive guns or hot melt guns, which apply high temperatures in the range of 100°C to more than 200°C to melt circular tubes of thermoplastic adhesives.