Home Repair and Paint Guide

... The choice can be made easier by classifying an adhesive by intended use or chemical type. The strongest adhesives solidify by a chemical reaction. These also tend to generate heat during the process, sometimes getting quite hot. If you have ever performed any type of auto bodywork using plastic filler, you have experienced this type of reaction. Weaker types harden by some type of physical change. Toughened acrylics are fast curing and used where high strength and resistance to fatigue are needed. They are available in one or two part compounds. In two part systems, adhesive is applied to one substrate and activator to the second. 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 ...