How nylon is made

Nylon was invented at DuPont and announced in 1938, after an eleven-year research program.

stations: 6
things upstream: 11
raw sources: 5
steps from the ground: 5

The short version

Nylon 66 is made by combining adipic acid with hexamethylenediamine into a salt, then heating the salt in a pressure vessel so water leaves and long chains form. The molten polymer is cast into ribbon and chopped into chips, or melted again and spun through tiny holes into filaments that are stretched to align the chains.

Make adipic acid

Benzene from refined naphtha is converted through intermediate compounds, and the last step is oxidation with nitric acid. The product is a white crystalline acid.

Goes in
Benzene Nitric acid
Make the diamine

Adipic acid is processed with ammonia into the other half of the nylon, hexamethylenediamine. Both halves have six carbon atoms, which gives nylon 66 its name.

Goes in
Ammonia
Marry them into a salt

The acid and the diamine are mixed in water in equal amounts, which forms nylon salt. A salt makes the balance exact, and the chains will only grow long if the halves match.
Heat it into long chains

The salt solution is concentrated and heated in a sealed vessel. Water boils off as the molecules join, and the thickened melt becomes polyamide.
Spin it into filaments

The melt is forced through a plate pierced with fine holes, and the strands harden in a flow of cool air. Dozens of them are gathered into a single yarn.
Stretch to line up the chains

The yarn is stretched to several times its length, which aligns the molecules along the fiber and makes it strong. It is then wound onto bobbins for weavers and knitters.

End of the lineNylon Next it goes into toothbrush, mascara, camera drone and 34 more.

Worth repeating

Wallace Hume Carothers first made nylon 66 on February 28, 1935, at DuPont's Experimental Station.
When nylon stockings first went on public sale in Wilmington, Delaware, in October 1939, all 4,000 pairs sold within three hours.
Paul Schlack at IG Farben developed nylon 6, based on caprolactam, in January 1938.