Thermosets
Thermoset, or thermosetting, plastics are synthetic materials that undergo a chemical change when they are treated, creating a three-dimensional network. After they are heated and formed, these molecules cannot be re-treated and reformed.
- History
- Properties
- Applications
- Processes
- Recycling
- Faq
History
The first commercial thermoset plastic was developed by Dr. Leo Baekeland in 1909.
It was a phenolic material trade named Bakelite. This thermoset material offered the new benefit of being firmly set -- not changing its shape, even under heat and pressure.
Bakelite was used extensively as an insulating material for handles on cookware and irons, and later found its way into applications such as telephone earpieces, electrical housings and connecting blocks. It was also a key ingredient in many of the weapons used in World War II.
Since that time, different thermoplastic types made their entry (see: types of plastics).
Properties
Thermosetting plastics retain their strength and shape even when heated. This makes thermosetting plastics well-suited to the production of permanent components and large, solid shapes. Additionally, these components have excellent strength attributes and will not become weaker when the temperature increases.
Each type of thermosetting plastic has a unique set of properties. Epoxies, for example, exhibit elasticity and exceptional chemical resistance, and are relatively easy to cure. Phenolics, while fairly simple to mold, are brittle, strong and hard. Because of their wide range of characteristics, thermosetting plastics find use in an extensive variety of applications, from electrical insulators to car bodies.
Applications
Thermosets have found applications in a wide variety of fields including:
- electronic chips
- fibre-reinforced composites
- polymeric coatings
- spectacle lenses
- dental fillings
Processes
Thermoset plastic products are typically produced by heating liquid or powder within a mold, allowing the material to cure into its hardened form. These products can be removed from the mold even without allowing it to cool. The reaction used to produce thermosetting plastic products is not always the result of heating, and is sometimes performed by chemical interaction between specialized materials. Typical types of thermosetting plastics are epoxies, polyesters, silicones and phenolics. Vulcanized rubber is also an excellent example of a thermosetting plastic.
Recycling
Thermosets are recoverable.
Energy recovery, feedstock recycling, grinding and reuse are all possible options.
