Thermosetten
Thermosetting polymers, commonly called thermosets, are a class of polymers that undergo irreversible curing to form a rigid, crosslinked network. Upon curing, they no longer soften upon heating, in contrast to thermoplastics which can be remelted and reshaped. The curing process can involve addition or condensation reactions and is typically initiated by heat, catalysts, or radiation. Once crosslinked, the material exhibits high thermal stability, chemical resistance, dimensional stability, and sometimes high mechanical strength, making them suitable for high-temperature or demanding chemical environments. However, because the network is irreversibly formed, thermosets are generally not recyclable by melting and are more brittle than many thermoplastics.
Common thermoset chemistries include epoxy resins, phenolic resins, unsaturated polyesters, vinyl esters, polyurethanes, melamine-formaldehyde and urea-formaldehyde
Manufacturing uses molding techniques such as compression molding, transfer molding, resin transfer molding, RTM, or casting;
Environmental considerations include emissions during curing and the challenge of end-of-life disposal; improvements include low-emission resins