poliammidi

Poliammidi, or polyamides, are a class of polymers characterized by repeating amide linkages (-CO-NH-) along their backbone. They can be aliphatic, such as nylon grades derived from aliphatic diamines and diacids, or aromatic, including aramids used for high-strength applications. Polyamides are among the most widely used synthetic polymers, balancing toughness, wear resistance, and chemical stability.

Most polyamides are prepared by condensation of diamines and diacids, or by polymerizing cyclic amide monomers (lactams) in a process known as ring-opening polymerization. Nylon 6 is produced from caprolactam, whereas Nylon 6,6 is formed from hexamethylenediamine and adipic acid. Aromatic polyamides, such as poly(p-phenylene terephthalamide) (aramids), are prepared from rigid monomers and exhibit very high heat resistance and tensile strength.

Key properties include high tensile strength and modulus, good abrasion and wear resistance, and chemical resistance to oils and solvents. Many polyamides absorb moisture from the environment, which can affect dimension and mechanical properties and raises processing considerations. Melting temperatures and glass transition temperatures vary with structure; crystalline nylons melt in the range of ~210–270°C, while aramids maintain high heat resistance.

Common applications span fibers for textiles and tire cords, films and molded parts, and engineering plastics for automotive, electronics, and consumer goods. Polyamides are also used in packaging, though barrier properties depend on crystallinity and processing. Environmentally, polyamides are not readily biodegradable; recycling is typically mechanical or chemical, with ongoing research into sustainable production and end-of-life options.