What is a Thermoset?
Thermoset plastics are polymers similar to, but generally stronger than, thermoplastics because of polymer cross-linking. Thermosets also have a higher resistance to heat. Cured thermoset resins may soften when heated, but will not melt or flow. Due to their inherent irreversibility, many thermosets cannot be recycled.
Filled or Reinforced Products
Products made from resins and modifiers such as pigments, plasticizers, or chopped fibers are known as filled or reinforced products. By contrast, unfilled resins, base polymers, and raw materials do not contain additives. Typically, raw materials are available as pellets, powders, granules, or liquids.
Fibers can be either chopped or wound, and commonly include glass, fiberglass, or cloth. Some products contain solid lubricant fillers such as graphite or molybdenum disulfide. Others contain aramid fibers, metal powders, or inorganic fillers with ceramics and silicates.
Vulcanized Thermosets
Vulcanization is a thermosetting reaction that uses a cross-linked compound or catalyst. In rubber-like materials, vulcanization results in greatly increased strength, stability, and elasticity. Traditionally, sulfur is used as the vulcanizing agent for natural rubber. Thermosets and thermoset materials may contain filler materials such as powders or fibers to provide improved strength and/or stiffness.
Uses & Types of Thermoset Products
Thermoset molding compounds are designed for processes such as Reaction Injection Molding (RIM) and Resin Transfer Molding (RTM). Composite thermoset materials consist of a matrix and a dispersed, fibrous, continuous second phase. Casting resins include a catalyst or hardener. Thermoset electrical resins and electronic-grade products are used in potting or encapsulating compounds, conductive adhesives, and dielectric sealants.
Thermal compounds are designed to form a thermally conductive layer on a substrate, either between components or within a finished electronic product. Thermoset purging compounds are used to clean molding machines between runs of different colors or compositions. Gap filling products are used to fill in gaps or spaces between two surfaces to be bonded or sealed.