thermosetit

Thermosetting polymers, also known as thermosets, are polymers that irreversibly cure into a rigid, cross-linked network. Unlike thermoplastics, once cured they do not melt or flow upon reheating. The cross links are formed by chemical reactions during curing, typically through polycondensation or addition curing, producing a material with high thermal and chemical resistance.

Processing involves combining a resin with a curing agent or hardener and exposing it to heat, pressure, or catalysts. The curing step creates a three‑dimensional network that imparts rigidity, dimensional stability, and often high glass transition temperatures. Once set, the material retains its shape and properties under elevated temperatures.

Common families include epoxy resins (cured with amines or anhydrides), phenolic resins (phenol–formaldehyde), melamine-formaldehyde and urea-formaldehyde resins, unsaturated polyester resins (cured with styrene), and silicone resins. Other thermosets include certain polyurethanes and composite matrices. Bakelite is a classic early example of a thermosetting polymer.

Applications of thermosets are widespread: coatings and paints, structural and protective adhesives, electrical insulators and encapsulants, laminates in printed circuit boards, wire insulation, and composite materials for aerospace, automotive, and sport equipment. They offer high temperature resistance, chemical stability, and strong dimensional maintenance, but can be brittle and are challenging to recycle through conventional remelting.

Recycling options include energy recovery, mechanical recycling into fillers or reclaimed resin, or chemical recycling to break down networks into smaller molecules. Environmental and health considerations during production and curing, such as emissions from formaldehyde-based resins, are important factors in their use and handling.