Heat-resistant plastic is a body of materials composed of synthetic chemicals, usually polymers, which create a variety of physical properties. Petroleum and hydrocarbon atoms are strung into long molecules called monomers, and straight or branched chains of these molecules can be combined into polymers of various two- or three-dimensional structures. This polymerization can create two varieties of plastics: thermoplastics and thermosetting plastics. Thermoplastics soften under heat and harden with cooling; thermosetting plastics harden after the first heating and form links with other plastic molecules that never soften again. Materials may be fashioned into a wide variety of products meant to withstand heat, such as engine components, appliance or light housing, and fire-protection equipment.
Thermoplastics are typically melted and then shaped. They retain their shape when cool but are able to be recycled by melting and reshaping the material into a new product. Such materials include familiar products like polyethylene and polystyrene. Thermosetting polymers, on the other hand, are a heat-resistant plastic that may soften but not flow, so are normally formed and produced in a single step. Examples include epoxy resins, melamine, and polyester.
Many materials of heat-resistant plastic polymers exist in common and uncommon varieties. Thermoplastics comprise polycarbonates, polypropylene materials, and elastomer. Thermosets make alkyds, esters, and phenolics. Other thermoplastic resins can be mixed with materials to form copolymers and may be referred to by either their chemical names or the more common names popularized by the companies that developed them. For example, acrylic sheets are sometimes called Plexiglas®, while polyimide may be better known as Lexan®.
Some heat-resistant plastic materials are molded from thermosets for durability in extreme conditions. High heat applications in the home include products like ashtrays and cookware. Industrial and military applications for thermosets can involve placements in electrical and electronic technologies. Manufacturing techniques include transfer, compression, or injection molding. These processes allow for mass production with shorter production cycles and less cost.
Appearing in a wide range of product applications in modern manufacture, heat-resistant plastic materials are fashioned into products from common household technologies to critical high-performance equipment. Bio-based and degradable varieties are also made. These adhere to health standards and are used in feedstocks and compostable bags for organic waste.
Many polymers are compounded with additives to enhance their material properties. These can include reinforcing fibers, ultraviolet inhibitors, and flame retardants. Their versatility allows for exacting customizations of conventional and innovative material properties.