Nylon Defined

What Nylon Is, in Chemical Terms

Nylon is the generic name for a family of synthetic polymers called polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station. The name polyamide comes from the characteristic amide groups in the backbone chain, the repeating units linked by amide bonds that give the material its structure. Nylon was the first commercially successful synthetic polymer, and it remains one of the most commonly used polymers in both fiber and solid form.

The two common commercial types dominate the definition. Nylon 6 is made from caprolactam, while nylon 6,6 is made from adipic acid and a diamine, and the numbers record the carbon atoms in the building blocks. In one common production approach, molecules with an acid group on each end react with molecules containing amine groups on each end, forming monomers that are then reacted into long polymer chains. About 24 percent of nylon 6 goes into engineering resins and the rest into nylon fibers, which are made into textile, carpet and industrial yarns.

From Toothbrush Bristles to Nylons

Nylon is a thermoplastic, silky material, and its commercial debut was modest: it was first used in a nylon-bristled toothbrush in 1938. Fame arrived two years later with women's stockings, the famous women's stockings sold simply as nylons in 1940. Nylon had been intended as a synthetic replacement for silk, and when silk became scarce during World War II it substituted for silk across military production as well as hosiery.

The wartime record is remarkable. Nylon replaced Asian silk and hemp in parachutes and was used in flak vests, tires, tents, ropes, ponchos and other military supplies, and even in a high-grade paper for United States currency. The fiber balance of the era shifted with it: at the outset of the war cotton accounted for more than 80 percent of fibers used, while by August 1945 manufactured fibers had taken a market share of about 25 percent. Nylon had proved, under pressure, that a synthetic fiber could carry national-scale demand.

Properties That Explain Its Uses

Nylon is built for hard work. It offers a range of luster, from very lustrous to semilustrous or dull, and its high-tenacity fibers serve in seatbelts, tire cords, ballistic cloth and other demanding uses. It has high elongation, excellent abrasion resistance and high resilience, and nylon fabrics are heat-set so they hold their shape. It resists insects, fungi, molds, mildew, rot and many chemicals, has good specific strength, and characteristically melts instead of burning.

Those properties map directly onto its product list. Nylon fibers appear in fabrics, bridal veils, carpets, musical strings and rope. Solid nylon serves in mechanical parts such as machine screws, gears and other low- to medium-stress components once cast in metal, and in everyday objects like hair combs. Engineering-grade nylon is processed by extrusion, casting and injection molding, and related polyamides called aramids, with aromatic groups in the main chain, make excellent ballistic fibers.

Nylon 6,6 and the Engineering Grades

Type 6,6, sold in forms such as Nylon 101, is the most common commercial grade of nylon, while nylon 6 is the most common commercial grade of molded nylon. Nylon 6,6 is a general-purpose extruded grade that is tough, with good electrical insulating properties and noise-dampening characteristics. Of the unmodified nylons it has the highest melting point, is the strongest and the most rigid, and it was the first nylon material available in rod, sheet and tube form for industrial application.

Nylon resins generally are noted for high tensile strength, excellent abrasion, chemical and heat resistance, and a low coefficient of friction, which is why they appear in automotive parts, electronics, industrial components and films for food packaging as well as in fabric, carpeting, sportswear and recreational equipment. Variants extend the range: glass-filled nylon increases structural and impact strength and rigidity, molybdenum sulfide-filled nylon increases lubricity, and nylon 6,12 offers a higher temperature rating and lower water absorption than 6,6. For deeper background, see About Nylon on Apparel Search.

Directory Listings

The listing below profiles DuPont, the company that developed nylon.