Polyamiden

Polyamides, also known as nylons, are a family of polymers that contain amide linkages (-CO-NH-) in their main chain. They can be synthetic or bio-based and are among the most widely used engineering polymers. Most synthetic polyamides are produced by condensation of diamines with dicarboxylic acids, or by polymerization of lactams such as caprolactam. Common varieties include nylon 6, nylon 6,6, and nylon 12, with numerous copolymers and semi-aromatic grades also in use.

Properties of polyamides include high tensile strength, stiffness, and excellent abrasion resistance, along with good chemical resistance to oils and fuels. They are often semi-crystalline, which contributes to strength and heat resistance but makes them sensitive to moisture. Water uptake can increase dimensional changes and reduce mechanical properties. Thermal properties vary by grade, but many nylons melt in the 180–270°C range, enabling melt processing.

Processing and applications: Polyamides are melt-processable and widely used in injection molding, extrusion, and fiber formation. Reinforcement with glass or carbon fibers improves stiffness and heat resistance. Applications include textiles and carpets, automotive components, gears and bearings, electrical connectors, and housings for consumer electronics.

Variants and sustainability: Bio-based polyamides such as PA11 and PA1010 are derived from renewable feedstocks, offering lower fossil energy use. Recycling can be mechanical or chemical, with chemical recycling depolymerizing nylon back to monomers in some processes.

Limitations and aging: Moisture sensitivity, hydrolysis at elevated temperatures, and UV exposure in certain grades may affect performance. Additives and stabilizers are commonly used to tailor durability and processing.