Polyamid

Polyamide is a class of polymers containing amide linkages (-CO-NH-). The term covers a broad range of materials, including aliphatic nylons and aromatic polyamides known as aramids. They are commonly produced by condensation polymerization of diamines and dicarboxylic acids or by ring-opening polymerization of cyclic monomers such as caprolactam.

Nylon 6,6 and nylon 6 are among the most widely used polyamides. Nylon 6,6 is formed from hexamethylenediamine and adipic acid with the release of water; nylon 6 is produced by polymerizing caprolactam. Aramids, such as Kevlar and Nomex, are polyamides with rigid aromatic backbones and exhibit high thermal stability and flame resistance.

Polyamides generally exhibit high tensile strength, good abrasion resistance, and chemical resistance, but they are hygroscopic; moisture absorption increases dimensional changes and affects properties. They have a relatively high melting temperature and can be processed by extrusion, injection molding, and fiber spinning. Applications include textile fibers, automotive components, electrical insulation, and consumer goods.

Environmental aspects include non-biodegradability and energy-intensive production. Recycling methods include mechanical recycling of blends and chemical recycling via depolymerization to monomers. Lifecycle considerations are important in design and use.