Polyurethane is a substance categorized as a polymer based on its chemical structure. It is manufactured by combining a diisocyanate and a diol, two monomers, through a chemical reaction. This makes a basic material whose variations can be stretched, smashed, or scratched, and remain fairly indestructible. Depending on the different diisocyanates and diol or polyol constituents, the resulting polyurethane might take a liquid, foam, or solid form, each with advantages and limitations.
Some polyurethane is categorized as an elastomer. It has elastic properties while maintaining some rigidity, such as in the wheels of a dolly that absorb shock but don’t compress too much. It can be extremely flexible when used as a foam insulator in construction or a foam cushion in upholstery. It can also be deformed several times and still maintain its original shape; in other words, it has a structural memory.
Another polyurethane material is a thermoplastic that resembles other kinds of plastic, metal, or fiberglass. Thermoplastics are rigid and smooth with a sealed surface impermeable to water. These are used when strength and durability are important, such as in seats at an airport terminal or packaging crates on a truck. Some polymer thermoplastics are difficult to recycle, but they can be reused.
Memory foam is polyurethane with additional chemicals increasing its viscosity and density. It is often referred to as “visco-elastic” polyurethane foam, or low-resilience polyurethane foam. Higher-density memory foam softens in reaction to body heat, allowing it to mold to a warm body in a few minutes. A lower-density memory foam is pressure-sensitive and molds quickly to the shape of a body pressing against it, returning to its original shape once the pressure is removed.
Today, we can find polyurethane in every room of our house and practically everywhere we go. Since this material’s popularity grew during World War II, the polymer has protected, reinvented, joined, or transported countless items.