What are thermosetting polymers?

Thermosetting polymers are a type of polymer that hardens permanently after being heated and cannot be remoulded.

Thermosetting polymers, also known as thermosets, are a class of polymers that are irreversibly hardened by curing from a soft solid or viscous liquid. The curing process is induced by heat or suitable radiation and may be promoted by high pressure, or mixing with a catalyst. Once hardened, a thermoset cannot be melted for reshaping, in contrast to thermoplastic polymers which can be melted and reshaped multiple times.

The key characteristic of thermosetting polymers is their ability to retain their shape once they have been heated and moulded. This is due to the cross-linking of polymer chains that occurs during the curing process. Cross-linking is the formation of chemical links between the polymer chains, creating a three-dimensional network of connected molecules. This network gives thermosetting polymers their rigidity and heat resistance.

Examples of thermosetting polymers include polyurethanes, which are used in foam insulation and furniture, and epoxy resins, which are used in adhesives and coatings. Other examples are phenol-formaldehyde resins (used in the production of plywood) and melamine-formaldehyde resins (used in kitchenware and laminates).

The properties of thermosetting polymers make them suitable for a wide range of applications. They are often used in situations where high heat resistance is required, such as in the manufacture of electronics and appliances. They are also used in the automotive industry for parts that need to withstand high temperatures, such as under-the-hood components. Despite their heat resistance, thermosetting polymers are not indestructible. They can degrade and break down over time, especially when exposed to UV light or harsh chemicals.