Definitions for "Thermoset"
A plastic that is substantially infusible and insoluble after having been cured by heat or other means.
A plastic that, when cured by application of heat or chemical means, changes into a substantially infusible and insoluble product. Examples of thermoset pipes are fiberglass/epoxy composite pipe, red-thread pipe, fiberglass pipe; all must comply with ASTM D 2517 in order to be used under Part 192.
A plastic that undergoes a non-reversible chemical reaction when it is cured. Subsequent heating will not melt it. Examples are polyester, phenolic, melamine, epoxy, and silicone.
A material which hardens when first exposed to high temperatures and pressure but cannot be remelted without destroying its attributes.