Adhesives
By Elliott • June 1, 2009 12:14 PM
... One good example of a two part system is the adhesive that you can purchase at auto parts stores to attach a rear-view mirror to a windshield. Anaerobic adhesives cure when in contact with metal and air is excluded, such as a bolt driven into threads. They are often known as locking compounds and secure threaded parts. Cyanoacrylate adhesives cure through reaction with moisture held on the bonded surfaces. They need close fitting joints and solidify in seconds. Cyanoacrylates are used to join small plastic parts and rubber. Epoxy consists of an epoxy resin and hardener. There are a lot of different resins and hardeners available to cover a wide range of materials. Epoxy adhesive has good strength and low shrinkage. However, epoxies can have low peel strength and some tend to be brittle. Epoxy adhesives are available in one part, two part, and film forms. Polyurethane adhesives are chemically reactive, fast curing one or two part systems. They provide strong joints which are impact resistant and have good low temperature strength. Polyurethanes are useful for bonding glass fibre reinforced plastics (GRP). The fast cure usually necessitates machine application. Silicones are not very strong as far as adhesives are concerned. Their main features are flexibility and high temperature resistance. They are available in single or two part forms. Single part silicones are often used as bath and shower sealants, especially around tubs, sinks, and where ceramic tile meets the top of tub surfaces. Their adhesion to surfaces is only fair, but flexibility and durability are excellent. The two part versions require a hardening agent. Two part silicone systems work better in thick sections than single part types ...
