poliamide

A polyamide is a type of polymer in which the repeating units contain amide linkages (-CO-NH-). The term covers a broad family that includes synthetic nylons and aramids, as well as related polymers produced by bio-based routes or through lactam ring-opening polymerization. It is widely used to refer to materials with fibers and engineering plastics derived from polyamides.

Most polyamides are formed by condensation reactions between diamines and diacids, releasing water or other small molecules. An alternative route is the ring-opening polymerization of cyclic amide monomers such as caprolactam to yield nylon-6. Nylon-6,6 is produced from hexamethylene diamine and adipic acid. Aramids are polyamides with rigid aromatic structures, giving high thermal stability and flame resistance.

Polyamides typically exhibit high strength and stiffness, good abrasion and impact resistance, and chemical resistance. They tend to absorb moisture from the environment, which can alter mechanical properties and dimensional stability. Processing is often by melt extrusion or injection molding for plastics, and by melt-spinning for fibers.

Nylon fibers are used in textiles, carpets, and tire cords; engineering polyamides serve in automotive components, electrical parts, and consumer electronics. Aramids are used in flame-resistant applications such as body armor and protective gear. Some polyamides are used in packaging films and specialty coatings.

Nylon was developed in the 1930s and helped inaugurate the era of synthetic polymers. Environmental considerations include energy use in production, moisture-related behavior, and recycling challenges; chemical recycling and mechanical recycling are active areas of study and development.