What Is A Thermoset?
Adj. 1. thermoset - having the property of becoming permanently hard and rigid when heated or cured; "the phenol resins and plastics were the original synthetic thermosetting materials"
More About Thermosets
Thermosetting plastics (thermosets) are polymer materials that irreversibly cure to a stronger form. The cure is done through heat and a catalyzed chemical reaction though most often pressure is also applied. Thermoset materials, most often presented as a compound, can be liquid, powder, granular or dough like prior to molding and curing into their final form. The curing process transforms the resin into a solid plastic by a cross-linking process. Energy and catalysts are added that cause the molecular chains to react at chemically active sites (unsaturated or epoxy sites, for example), linking into a rigid, 3-D structure. The cross-linking process forms a molecule with a larger molecular weight, resulting in a material with a higher melting point. Thermoset materials are generally stronger than thermoplastic materials due to this 3-D network of bonds, and better suited to high-temperature applications and applications where creep and fatigue are concerns. While thermoset materials cannot be melted and re-shaped after being cured such parts can be recycled as filler material.
Some examples of thermosets are:
* Bakelite, phenolic, a phenol-formaldehyde resin (used in electrical insulators and automotive parts)* Urea-formaldehyde resins and molding compounds (used in plywood, particleboard and wiring devices)
* Melamine resins and molding compounds (used on worktop surfaces and dinnerware)
* Epoxy resin (used as an adhesive and in fibre reinforced plastics such as glass reinforced plastic and graphite-reinforced plastic)
* DAP ( used in military electrical connectors and nuclear reactor auxillary and control components)
* bulk molding compound (bmc, smc, dmc), thermoset polyester, used in electrical, automotive, appliance, tableware, esthetic and outdoor applications
Some methods of molding thermosets are:
* injection molding and injection compression molding* Resin transfer, prepreg and hand lay up
* Compression molding (used to shape most thermosetting plastics) and transfer molding
* thermoset extrusion