Thermoset Plastics - Deconstructed
Thermosets are a group of engineering plastics particularly well suited to demanding requirements. The common thermoset materials include Phenolics (Bakelite), Diallyl Phthalates (DAP), Epoxies, and Polyesters. These materials offer outstanding performance, proven through decades of successful use. They also offer cost savings as a replacement for metals and are
an alternative to plastics that offer similar performance but at a greater cost. Thermoset plastics have ability to withstand heat and pressure for long periods of time without failure. The dimensional stability, creep resistance, chemical resistance, stiffness, and high temperature capabilities make them the number one choice where reliable performance in adverse conditions is required. Thermoplastics can be heated to liquid then cooled in any desired shape, similar to melting a wax candle and then cooling back to a solid. Molecules in thermoset materials, when exposed to heat and pressure, interconnect and cross link forming new molecules. This chemical reaction is irreversible; the thermoset cannot be remelted. For applications requiring precise dimensional tolerances and low deformation under load, thermosets are an excellent choice. Other preferable characteristics of thermoset materials are its excellent impact resistance and extraordinary electrical insulating properties. Some engineered thermoplastics claim high temperature resistance; however, in this area, these materials cannot compete with thermosets and may run the risk of deformation under load when approaching their heat deflection temperature. Phenolics and Epoxies are commonly selected for metal replacement. The ability to mold these materials into complex shapes is cost effective, eliminating the need to machine features of a design. Also, molding features in lieu of machining, permits closer tolerances. Dimensional stability of these materials insures that close tolerances can be maintained and repeatable within ten thousandths of an inch. Requirements for component performance in harsh environments in the electrical, aerospace, nuclear and military applications are satisfactorily met by thermoset plastics. The range of properties of thermoset materials is diverse. Epoxy carbon fiber materials achieve extremely high strength and Phenolics have temperature resistance of 450 degrees F and Silicones with even higher. Basic knowledge of thermoset plastics capabilities can help to decide which material is best suited for a project on both an economic and performance basis. These compounds have not only survived in the ever-expanding plastics industry but also have evolved into the elite molding materials within the field.
