Nylon

• 1. Introduction

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  Nylon stockings sold out in three hours when 4,000 pairs first went on public sale in Wilmington, Delaware, on the 24th of October 1939. Within a year of its national release, 64 million pairs had sold, and by 1946, when postwar supply still could not meet demand, an estimated 40,000 people lined up in Pittsburgh just to buy 13,000 pairs. Nylon is a family of synthetic polymers built from amide linkages, and it became the first commercially successful synthetic thermoplastic polymer in history. What turned a laboratory curiosity from DuPont into a fabric that thousands of Americans would riot to obtain, and how did a stocking, a toothbrush and eventually a rifle stock all end up made from the same material?

• 2. Invention at DuPont

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  Wallace Hume Carothers, a Harvard instructor, arrived at DuPont to direct a new polymer research group after chemist Charles Stine proposed in 1927 that the company organize small teams around pioneering research meant to lead to practical applications. Carothers was initially free to pursue pure research, testing the theories of German chemist Hermann Staudinger, work that greatly advanced the broader understanding of polymers. In the spring of 1930 his team synthesized two new polymers: neoprene, a synthetic rubber that would see heavy use in World War II, and an elastic paste that grew very strong on cooling, the eventual precursor to nylon. After those discoveries, Carothers' group shifted from pure research toward a narrower goal, finding one chemical combination suited to industrial use. His coworker Julian W. Hill, a Washington University alumnus, had already developed a cold drawing method to produce a polyester in 1930, and Carothers used that same method in 1935 to finish developing nylon. On the 28th of February 1935, at DuPont's Experimental Station, the team produced polymer 6-6, the first true nylon, with the elasticity and strength DuPont wanted, though it required a complex manufacturing process that would later underpin industrial production. DuPont patented the polymer in September 1938. Carothers never saw the announcement: he died 16 months before it was made. The name itself came from modifying “norun”, meaning no run, into something marketable, though it was never trademarked. Separately, in response to Carothers' work, Paul Schlack at IG Farben developed a different molecule based on caprolactam, nylon 6, on the 29th of January 1938. Producing nylon required three DuPont departments working together: Chemical Research, the Ammonia Department and the Department of Rayon. Some of nylon's key ingredients depended on high pressure chemistry, the Ammonia Department's specialty, and the material arrived as what the company called a godsend to a division then in financial trouble; the reactants used to make nylon eventually made up half of the Ammonia Department's sales, helping pull it out of the Great Depression by creating new jobs and revenue. The project also demonstrated the value of chemical engineering to industry more broadly, building a plant that provided 1800 jobs using the latest technology of its era, a model still referenced by chemical plants today. The first nylon plant opened in Seaford, Delaware, starting commercial production on the 15th of December 1939. On the 26th of October 1995, the American Chemical Society designated the Seaford plant a National Historic Chemical Landmark.

• 3. Selling a Miracle Fiber

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  DuPont unveiled nylon publicly on the 27th of October 1938, at the final session of the Herald Tribune's annual Forum on Current Problems, staged on the very site where the coming New York World's Fair would rise. Billed as the first man-made organic textile fiber, spun from coal, water and air, and promised to be as strong as steel and as fine as a spider's web, the announcement drew an enthusiastic response, much of it from middle-class women in the audience, and made headlines across the country. Nylon appeared as part of “The world of tomorrow” at the 1939 New York World's Fair and again at DuPont's “Wonder World of Chemistry” at San Francisco's Golden Gate International Exposition that same year. Five days after the announcement, President Roosevelt's cabinet discussed nylon's “vast and interesting economic possibilities.” Yet the hype created its own problems: unrealistic claims that nylon would outlast silk and truly never run, captured in headlines like “New Hosiery Held Strong as Steel” and “No More Runs,” forced DuPont to walk back its early promises about matching the strength of steel. Consumer unease ran deeper too. A damaging news story built on DuPont's 1938 patent suggested nylon might be produced using cadaverine, a chemical drawn from corpses; scientists pointed out that cadaverine could also be extracted by heating coal, but the public often refused to listen, and one woman confronted a lead DuPont scientist directly, unwilling to accept his denial. DuPont answered by shifting its campaign to emphasize that nylon came from “coal, air and water,” moving the focus toward personal and aesthetic appeal with slogans such as “If it's nylon, it's prettier, and oh! How fast it dries!”

• 4. Stockings, War and Riots

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  Actual nylon stockings did not reach selected stores nationwide until the 15th of May 1940, though a limited supply had already gone on sale earlier in Delaware; on the 24th of October 1939, in Wilmington, all 4,000 available pairs sold within three hours. In 1940 alone, DuPont produced 1300 tons of the fabric, and 64 million pairs of stockings sold in that first year, priced at about one and a half times the cost of silk, $4.27 per pound of nylon against $2.79 per pound of silk. Rising hemlines helped drive sales too; as one historian, Lauren Olds, put it, by 1939 hemlines “had inched back up to the knee, closing the decade just as it started off,” creating demand for stockings that offered coverage without garters. A second plant opened in Martinsville, Virginia, in 1941 to keep pace with demand. That momentum broke on the 11th of February 1942, when nylon production was redirected entirely to the military; DuPont halted stocking and lingerie manufacture, and most nylon went into parachutes and tents for the war, while stockings already made before the switch sometimes sold on the black market for as much as $20. When the war ended, DuPont projected annual production of 360 million pairs of stockings, but delays in reconverting factories meant demand still went unmet in 1946, sparking what became known as the nylon riots, including the scene in Pittsburgh where roughly 40,000 people queued for only 13,000 pairs. In the meantime, women repurposed wartime nylon tents and parachutes into blouses and wedding dresses. Between the war's end and 1952, stockings and lingerie consumed 80 percent of the world's nylon output, and DuPont kept expanding production to meet civilian demand.

• 5. Blends, Flaws and a New Name

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  Pure nylon hosiery, once it reached a wide market, revealed real weaknesses: threads tended to unravel lengthwise into runs, the fabric felt uncomfortable because it lacked absorbency, trapping moisture near the skin instead of wicking it away, and it could itch, cling and spark from static buildup. Some stockings even degraded, perforating or shredding, a problem scientists traced to acid hydrolysis caused by air pollution, blaming London smog in 1952 along with poor air quality in New York and Los Angeles. The fix was blending, combining nylon with cotton, polyester, spandex and other fibers to keep its elasticity, durability and dye-friendliness while lowering the price of finished clothes. By 1950 the New York Quartermaster Procurement Agency, which developed and tested textiles for the Army and Navy, had committed to a wool-nylon blend, and it was far from alone; America's Textile Reporter called 1951 the “Year of the blending of the fibres,” and new combinations like “Bunara,” a wool-rabbit-nylon mix, and “Casmet,” blending wool, nylon and fur, appeared on the market. DuPont's Fabric Development Department also courted French fashion, supplying samples to designers; in 1955, Coco Chanel, Jean Patou and Christian Dior all showed gowns made with DuPont fibers, with photographer Horst P. Horst hired to document the results, and American Fabrics credited the blends with opening “creative possibilities and new ideas for fashions which had been hitherto undreamed of.” In 1940, DuPont's John W. Eckelberry said the letters “nyl” were chosen arbitrarily, with “on” borrowed from the suffixes of fibers like cotton and rayon. A later DuPont publication, in Context, volume 7, number 2, from 1978, told a fuller story: the name was meant to be “No-Run,” until DuPont pulled back from that unjustified claim, swapping the vowels to get “nuron,” then changing it to “nilon” to sound less like a nerve tonic, before finally shifting the “i” to a “y” for clearer pronunciation. A persistent urban legend claims the name blends “New York” and “London,” but no organization in London had any part in nylon's research or production.

• 6. The Chemistry of Nylon

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  Chemists use “PA,” short for polyamide, interchangeably with “Nylon,” and the naming system, devised during the earliest aliphatic nylons, counts the carbons in each monomer, including those in the carboxylic acid groups, with letters added later once cyclic and aromatic monomers entered use. Nylon 6, written NH minus (CH2)5 minus COn, comes from ε-caprolactam and represents a homopolymer built from a single monomer, while two-number types like Nylon 6,10, made from hexamethylenediamine and sebacic acid, form from a diamine and a dicarboxylic acid, the first number naming the diamine's carbon count. Copolymers such as PA 6/66, made from caprolactam, hexamethylenediamine and adipic acid, separate their comonomers with slashes. When 60 percent or more of a polymer's carboxylic acid content combines terephthalic acid and isophthalic acid, chemists call it polyphthalamide, or PPA. Nylon 66, patented by Carothers at DuPont, forms when a diamine and a dicarboxylic acid react in equal parts, producing a repeating ABAB structure similar to many polyesters and polyurethanes, though unlike natural polyamide proteins, its amide bond direction reverses at each monomer rather than running consistently from the C terminal to the N terminal. Getting the diamine and acid proportions exactly right is difficult, and small deviations can stop the chain from growing past a molecular weight of 10,000 daltons, so manufacturers first form a crystalline “nylon salt” at room temperature from a precise 1:1 ratio of acid and base, purify it by crystallization, then heat it to 285 C, releasing water as the salt reacts into nylon polymer. Homopolymers, by contrast, come from a single monomer, either a lactam or an amino acid, such as nylon 6, or polycaprolactam, formed through ring-opening polymerization that breaks the peptide bond inside caprolactam so both exposed ends join the growing polymer chain. Nylon 6 melts at 220 C, notably lower than nylon 66's 265 C melting point. Nylons can also form through acid catalysis from dinitriles, as with nylon 1,6, made from adiponitrile, formaldehyde and water, and similarly from diols and dinitriles. Mixing monomers produces copolymers with lower crystallinity and melting points, and because most nylon polymers are miscible with one another, a wide range of blends is possible, with the two polymers able to react through transamidation into random copolymers. Above its melting temperature, nylon behaves like an amorphous solid or a viscous fluid of randomly coiled chains; below that point, amorphous regions alternate with lamellar crystal regions, the amorphous parts supplying elasticity and the crystalline parts supplying strength and rigidity. Its planar amide groups are strongly polar, letting nylon form many hydrogen bonds between neighboring strands, and because the backbone is so regular, particularly when its amide bonds sit in the trans configuration, nylon tends toward high crystallinity, making it an excellent fiber material. In nylon 66, parallel strands can align their peptide bonds at coordinated gaps of exactly six and four carbons over long stretches, letting carbonyl oxygens and amide hydrogens line up in uninterrupted interchain hydrogen bonds, similar to the structure of natural silk fibroin and the beta-keratins found in feathers, while nylon 510 achieves the same effect with runs of five and eight carbons; nylon 6 forms uninterrupted hydrogen-bonded sheets too, though with mixed directionality and a somewhat different wrinkling pattern. Block nylon stays less crystalline except near surfaces sheared during formation, and while nylon itself is clear, colorless or milky, it takes dye easily, and multistranded nylon cord tends to slip and unravel unless its ends are melted with a flame or electrode. Because nylon is hygroscopic, absorbing or releasing moisture with ambient humidity, its dimensions shift, and moisture acts as a plasticizer that lowers the glass transition temperature and, with it, the elastic modulus below that point. Nylon 66 in particular can be heat-set into pleats and creases, offers a more compact molecular structure, better weathering and sunlight resistance, a softer “hand,” a high melting point of 265 C, superior colorfastness and excellent abrasion resistance, while nylon 6 dyes more easily, fades faster, resists impact better, absorbs moisture more quickly and shows greater elasticity and elastic recovery. Nylon clothing generally resists flame better than cotton or rayon, though its fibers can melt and stick to skin instead of simply burning.

• 7. From Parachutes to Guitar Strings

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  During World War II, DuPont, along with Bill Pittendreigh and others, worked to replace Asian silk and hemp with nylon in military parachutes, and the material also went into tires, tents, ropes, ponchos and other supplies, even a high-grade paper for United States currency. Cotton had accounted for more than 80 percent of all fibers used at the war's outset, with wool covering nearly all the rest, but by August 1945 manufactured fibers held a 25 percent market share, mostly taken from cotton. Nylon 6 and 66 both went into carpet manufacture, and nylon became a standard fiber in tire cord after Herman E. Schroeder pioneered its use there. In molded form, nylon resin found heavy use under the hood in the automobile industry, in hair combs and in mechanical parts such as machine screws, gears and gaskets once cast in metal, with engineering-grade nylon processed by extrusion, casting and injection molding; Type 6,6 Nylon 101 became the most common commercial molding grade, and Nylon 6 the most common commercial grade overall, with glass-filled and molybdenum disulfide-filled variants used for added strength or lubricity in tools like spudgers, and nylon composites reinforced with glass or carbon fiber found their way into car parts such as intake manifolds, where heat resistance made them a real alternative to metal. The stock of the Remington Nylon 66 rifle was made from nylon, as is the frame of the modern Glock pistol. In the mid-1940s, classical guitarist Andrés Segovia complained to General Lindeman of the British Embassy about a shortage of his preferred Pirastro catgut guitar strings; a month later the General, working through contacts in the DuPont family, gave Segovia some nylon strings, which produced a clear sound with a faint metallic timbre Segovia hoped could be removed. Olga Coelho first played nylon strings on stage in New York in January 1944, and in 1946 mutual friend Vladimir Bobri, editor of Guitar Review, introduced Segovia to string maker Albert Augustine; DuPont, doubtful at first, agreed to supply nylon if Augustine developed the strings himself, and after three years he produced a first string that impressed Segovia and DuPont alike, eventually solving the harder problem of wound strings through experiments with different metals and polishing techniques.

• 8. Decline, Waste and Recycling

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  Nylon's popularity peaked through the 1940s and 1950s on the strength of its durability and sheerness, then found new favor in the 1970s for its flexibility and price, with textile consumption growing 7.5 percent a year between the 1960s and 1980s despite that decade's oil shortages. Even so, synthetic fibers overall fell from 63 percent of world textile production in 1965 to 45 percent in the early 1970s, as the appeal of “new” materials faded and nylon fabric, in one description, “was going out of style.” Growing concern over environmental costs, oil extraction, energy use, manufacturing waste and non-biodegradable disposal, added to that decline, and worldwide nylon production later settled at an estimated 8.9 million tons a year. Even with pure nylon now rarely used, its derivatives left a lasting mark: one historian compared the invention to Coca-Cola in the eyes of 20th century consumers, calling it “an object of desire.” The Lunar Flag Assembly, the first flag planted on the moon, was made of nylon, costing $5.50 but requiring a specially engineered horizontal flagpole bar so it would appear to fly in the absence of wind. Every nylon is vulnerable to hydrolysis, especially from strong acids, essentially the reverse of the synthesis reaction, and once attacked, molecular weight drops and cracks form quickly at the damaged zones, with lower-numbered nylons like nylon 6 affected more than higher ones like nylon 12, ruling nylon parts out for contact with sulfuric acid, as found in lead-acid batteries. Manufacturing a kilogram of nylon carpet produces an estimated 5.43 kilograms of carbon dioxide equivalent when made in Europe, close to wool's footprint but offset by nylon's greater durability, while data from PlasticsEurope puts nylon 66's footprint at 6.4 kilograms of carbon dioxide equivalent per kilogram and its energy use at 138 kilojoules per kilogram. In a fire, various nylons release hazardous smoke and toxic fumes or ash, typically containing hydrogen cyanide, and because incinerating nylon to recover its embedded energy usually costs too much, most nylon ends up decaying slowly in landfills, taking 30 to 40 years to break down as discarded fabric; nylon fishing gear, including nets, adds to ocean debris. The material recycles well in principle, and much resin returns to use directly at the injection molding machine by grinding sprues and runners back into the virgin granules being consumed, though recycling remains expensive and difficult overall, so most manufacturers favor cheaper new plastic instead. Patagonia sells products with recycled nylon and, in the mid-2010s, invested in Bureo, a company recycling nylon from used fishing nets into sunglasses and skateboards, while the Italian company Aquafil has demonstrated similar recycling of nets lost at sea into apparel. Nylon remains the most popular fiber in residential carpeting today; the US EPA estimated that in 2018, 9.2 percent of carpet fiber, backing and padding was recycled, 17.8 percent was incinerated for energy, and 73 percent went to landfill, a pattern some of the industry's largest carpet and rug companies are now working to shift under a “cradle to cradle” model that reuses non-virgin materials not historically recycled.