Polyamide (PA), commonly known as nylon, is a family of thermoplastic polymers characterized by repeating amide (–CONH–) linkages along the molecular backbone. These polar amide groups promote strong intermolecular hydrogen bonding, which contributes to relatively high strength, toughness, and wear resistance compared to many commodity plastics. As a result, polyamides occupy an important position between general-purpose thermoplastics and higher-performance engineering plastics. Their mechanical properties, thermal stability, and friction behavior make them suitable for components that must carry load, resist abrasion, and maintain dimensional integrity under repeated motion.
From a product design perspective, polyamides are widely used for gears, bushings, bearings, fasteners, and housings where a combination of strength, fatigue resistance, and low friction is required. They also exhibit good resistance to many oils, fuels, and solvents, which supports their use in automotive and industrial applications. However, polyamides are hygroscopic and absorb moisture from the environment, which can lead to changes in stiffness, dimensions, and impact resistance over time. Designers must account for this moisture uptake, especially in precision components or assemblies where tight tolerances are critical.
Polyamides are readily processed by injection molding and extrusion and can be reinforced with glass fibers or other fillers to further increase stiffness and heat resistance. Their relatively high melting temperatures compared to commodity thermoplastics allow service at moderately elevated temperatures, while still permitting conventional thermoplastic processing methods. For engineering applications requiring a durable, wear-resistant material with good load-bearing capability and compatibility with high-volume manufacturing, polyamide is a commonly selected material, provided that moisture-related dimensional changes are considered in the design stage.
The term “nylon” is commonly used in industry as a general name for polyamide (PA) materials, although it originated as a DuPont trade name for early commercial polyamides such as nylon 6,6. In modern usage, nylon typically refers to aliphatic polyamides including PA6 and PA66, while the more precise designation “PA” is preferred in technical standards and material specifications. Numerous manufacturers supply polyamide resins under proprietary trade names, such as Zytel, Ultramid, Akulon, and Technyl, each representing specific grades that may include reinforcements, stabilizers, or other additives. For product design, these trade names usually indicate differences in mechanical strength, wear resistance, thermal performance, or processing behavior, even though the base polymer chemistry remains within the polyamide family.