What is Thermosetting polymer?
A '''thermosetting plastic''', also known as a '''thermoset''', is [[polymer]] material that irreversibly [[Curing (chemistry)|cures]]. The curing may be done by: <br/>{{•}} heat (generally above {{convert|200|C}}) <br/>{{•}} a [[chemical reaction]] (two-part [[epoxy]], for example) <br/>{{•}} ir[[radiation]] such as [[electron]] [[beam]] processing Thermoset materials are usually [[liquid]] or [[malleable]] before curing, so they can be [[Molding|molded]] into their final form. Others are used as [[adhesive]]s. Others are solids. Some [[solid]] thermosetting polymers are used as molding compound in [[semiconductors]] and [[integrated circuits]] (IC). Once hardened a thermoset resin cannot be reheated and melted back to a liquid form. ==Process== The curing process transforms the resin into a [[plastic]] or [[rubber]] by a [[cross-link]]ing process. Energy and/or [[catalyst]]s are added that cause the molecular chains to react at chemically active sites (unsaturated or epoxy sites, for example), linking into a rigid, [[Dimension|3-D]] structure. The cross-linking forms a molecule with a larger molecular weight, resulting in a material with a higher [[melt]]ing point. During the reaction, the polymer's molecular weight increases to the point that its [[melting point]] is higher than the surrounding ambient temperature. So, the material forms into a solid material. Uncontrolled reheating of the material results in reaching the decomposition temperature before the melting point is reached. So, a thermoset material cannot be [[melt]]ed and re-shaped after it is cured. This implies that thermosets cannot be recycled, except as filler material.<ref>The Open University (UK), 2000. T838 ''Design and Manufacture with Polymers: Introduction to Polymers'', page 9. Milton Keynes: The Open University</ref> ==Properties== Thermoset materials are generally stronger than [[thermoplastic]] materials due to this three dimensional network of bonds (cross-linking). Thermoset materials are also better suited to high-[[temp