Nylon

by Chris Woodford. Last updated: June 2, 2023.

If wood is the world's most versatile natural material, nylon is probably the most useful synthetic one. It's a plastic that can be molded into everyday products or drawn into fibers for making fabrics—and its launch in the late 1930s truly changed the world.

Don't believe me? Let me explain. You can pretty much live your entire life with nylon by your side. You can snooze away on brushed nylon sheets until your alarm clock (powered by nylon gears) wakes you up. Hop across the nylon rug or carpet to your kitchen, maybe eat your breakfast from a nylon bowl, before cleaning your teeth with a nylon toothbrush. Hold a nylon umbrella over your head to keep out the rain when you set out for work or school or, if the sun's shining and you're heading to the beach, wear your quick-drying nylon-based swimming shorts instead. Feeling adventurous? You could try jumping from an airplane and have a nylon parachute bring you safely to the ground! Those are just a few of the things that nylon does for us every single day. What makes this material so amazing? Let's take a closer look!

Photo: Above: The world was introduced to nylon in 1938 when the DuPont chemical company used the material to make synthetic toothbrushes. Below: You can make nylon bristles pretty much any length. This amazing citrus fruit harvesting machine has nylon filaments that are about 3.5m (~12ft) long. They spin around and shake the fruit gently from the trees. Photo by Keith Weller courtesy of US Department of Agriculture/Agricultural Research Service (USDA/ARS).

What is nylon?

Nylon is a polymer—a plastic with super-long, heavy molecules built up of short, endlessly repeating sections of atoms, just like a heavy metal chain is made of ever-repeating links. Nylon is not actually one, single substance but the name given to a whole family of very similar materials called polyamides. So whenever we say "nylon is..." it's generally more correct to say "nylons are..." [1]

One reason there's a family of nylons is because the original and most common form of the material, nylon 6,6, was patented by E.I. du Pont de Nemours & Company (DuPont™), the US firm where it was invented, so rivals such as German chemical giant BASF had to come up with alternatives. Another reason is that the different kinds of nylon have different properties, which makes them useful for different things. Other kinds of nylon include nylon 6, nylon 6,12, and nylon 5,10. Two other "fantastic plastics" made by DuPont, Kevlar® (a superstrong material used in bulletproof vests) and Nomex® (a fireproof textile used in racing car suits and oven gloves), are also polyamides and they're chemically related to nylon.

Photo: Nylon couldn't wait to became a space-age material. In 1952, NASA rocket scientist Wernher von Braun proposed building a space station out of flexible nylon, which could be carried into space by a relatively small rocket and then inflated like a car tire. That concept never made it off the ground, but nylon still played its part in space history: the flag planted on the Moon by Neil Armstrong in 1969 was made from—guess what—nylon! Illustration by Chesley Bonestell courtesy of NASA Marshall Space Flight Center (NASA-MSFC). [2]

How is nylon manufactured?

Unlike traditional materials such as wood, iron, wool, and cotton, nylon does not exist in nature: we have to make it in chemical plants from organic (carbon-based) chemicals found in natural materials such as coal or petroleum. (It's also possible to make nylon from renewable materials; Zytel®, a type of nylon produced by DuPont, comes from castor oil—so, essentially, vegetables.) [3]

The nylon polymer is made by reacting together two fairly large molecules using moderate heat (roughly 285°C or 545°F) and pressure in a reaction vessel called an autoclave, which is a bit like an industrial-strength kettle. One of the starting molecules is called hexane-1,6-dicarboxylic acid (also called adipic acid) and the other is known as 1,6-diaminohexane (also called hexamethylenediamine). When they combine, they fuse together to make an even larger molecule and give off water in a chemical reaction known as condensation polymerization (condensation because water is eliminated; polymerization because a big, repeating molecule is produced). The large polymer formed in this case is the most common type of nylon—known as nylon-6,6 because the two molecules from which it's made each contain six carbon atoms; other nylons are made by reacting different starting chemicals. Usually this chemical process produces a giant sheet or ribbon of nylon that is shredded into chips, which become the raw material for all kinds of everyday plastic products.

Artwork: How nylon 6,6 is made by condensation polymerization. 1) The two ingredients are 1,6-diaminohexane (left, red) and hexane-1,6-dicarboxylic acid (right, black). 2) A hydrogen (H) from the (red) diaminohexane joins with a hydroxide (OH) from the (black) acid. 3) A water molecule (blue) is lost (which is why the process is called condensation) as the two molecules join together. 4) The same thing happens over and over again, making a bigger and bigger molecule from the same repeated components—the process we call polymerization.

Nylon clothes and similar products are made not from chips but from fibers of nylon, which are effectively strands of plastic yarn. They're made by melting nylon chips and drawing them through a spinneret, which is a wheel or plate with lots of tiny holes in it. Fibers of different length and thickness are made by using holes of different size and drawing them out at different speeds. Strands are sometimes used by themselves (for example, in the manufacture of stockings) and sometimes tens, hundreds, or even thousands are wrapped together to make thicker and stronger yarns (similar to cotton but far stronger).

Photo: Strong and lightweight: clothes aren't the only things made from nylon fabrics. Parachutes were originally made from silk; now they're more likely to be made from "ripstop" nylons. This parachute was designed to help the Mars Science Laboratory make a safe landing and is mostly nylon, with a small amount of polyester near the central vent. Photo courtesy of NASA/JPL-Caltech.

Photo: A closeup of the criss-cross reinforcement in ripstop nylon. These little rectangles are designed to stop rips or punctures from spreading, so a tiny tear won't get bigger by racing through the whole material.

How strong is nylon?

Photo: A box of 15-denier women's tights. You might take the "denier" to be an indication of strength, durability, opaqueness, coarseness, or thickness, but it's actually a measurement of thread weight.

If you've ever bought nylon tights or stockings, you'll know they're labeled in confusing units called deniers, which is defined as the weight in grams of 9000 meters of the yarn from which they're made. Loosely speaking, for people who wear nylon garments, the denier is a "proxy" measurement of strength, durability, and wear resistance, because stockings and other things made from thicker and heavier yarns tend to be stronger and last longer than finer ones. Denier is also related to the size of the nylon fibers from which a garment is made: the thinner the fibers, the lower the denier. Higher-denier fabrics tend to be coarser and more opaque (harder to see through).

Confused? Perhaps you've seen stockings for sale marked as "15 denier" or "40 denier" without ever really understanding what that means. If you see stockings described as 40-denier, it means a 9-km (roughly 6-mile) roll of the yarn they're made from would weigh just 40 grams (1.4 oz)—which gives you some idea just how fine nylon yarn really is! Tights and stockings with higher denier measurements are generally thicker and stronger; ones with lower denier measurements are more sheer and more fragile. Ultra-sheer tights, for example, are usually less than 10 denier; thick winter tights can be 100 denier or more.

Scientists are much stricter about all this: the denier isn't a measurement of strength, durability, or thickness at all. To measure thread strength, we'd need to use more carefully defined units, such as grams (force) per denier, technically referred to as the tenacity (effectively the breaking strength of a fiber and equivalent to measurements like kilograms per square centimeter or pounds per square inch for conventional materials). [4]

To give you an idea how strong nylon is, here's a chart of the ultimate tensile strength (again, loosely, the breaking strength) of some everyday materials. You can see that nylon is much stronger than you might think, but nowhere near as strong as metals like aluminum or steel.

Chart: Nylon is stronger than most forms of concrete and plastics such as polypropylene, but weaker than most woods and metals. [5]

Properties of nylon

Photo: These shorts are made from 70 percent cotton and 30 percent nylon, which means they're very soft and comfortable and dry much faster than 100 percent cotton shorts. Even so, both cotton and nylon absorb water, so these aren't the most practical fabrics for swim shorts; you'll find most swimwear is 100 percent polyester because it's much quicker drying.

Generally, nylon is a silky smooth thermoplastic (which means it melts and turns runny when you heat it up, generally at around 260°C or 500°F) that's strong, tough, and durable (it's reasonably wear-proof and resists sunlight and weathering). Since it's a synthetic plastic, it's highly resistant to attack from such natural nasties as molds, insects, and fungi. It's waterproof (hence its use in umbrellas and waterproof clothes) and fast-drying because (unlike with natural fabrics like cotton or wool) water molecules can't easily penetrate the outer surface. It does, however, absorb a certain amount of water, so it's less popular in swimwear than faster-drying synthetics such as polyester. Although reasonably resistant to quite a lot of everyday substances, nylon will dissolve in phenol, acids, and some other harsh chemicals.

Uses of nylon

It's almost easier to say what nylon isn't used for. Look around your home and you'll find it's packed with nylon. The first products made with this amazingly versatile chemical were toothbrushes and women's stockings. Later it was used in everything from tennis rackets and parachutes to inexpensive machine gears, fishing lines, and nylon rugs. Some cars even have body parts made from nylon!

Nylon isn't always used alone. In clothes, for example, it's often blended with natural textiles such as cotton, viscose (also known as rayon, a halfway-house, semi-synthetic made from trees and other plants), or other totally synthetic materials, including stretchy Spandex (also known as Lycra and Elastane) and quick-drying, easy-to-dye polyester.

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Find out more

On this website

• Kevlar®
• Nomex®
• Materials (a list of other materials articles on this site)
• Materials science

On other websites

• Fibers and Fabrics: A guide for students and teachers that describes the world of modern textile science, from the UK's National STEM Centre.
• Wallace Hume Carothers and Wallace Carothers and the Development of Nylon: Two great pages telling the story of how Wallace Carothers and his DuPont colleagues developed nylon.
• [PDF] Synthetic Fiber Manufacturing by Charles B. Weinberger, Dept of Chemical Engineering, Drexel University. August 30, 1996. A good overview of fiber-production techniques for an undergraduate audience. It covers synthetic fibers such as nylon and polyester, as well as things like fiber-optic cables. [Archived via the Wayback Machine.]

Articles

• February 23, 1935: Sheer bliss by Tony Long. Wired, February 28, 2011. Celebrating the first production of nylon by Du Pont.
• Nature's nylons by Michael Brooks. The Guardian, October 21, 1999. The quest for eco-friendly synthetic textiles.
• Julian W. Hill, Nylon's Discoverer, Dies at 91 by David Stout. The New York Times, February 1, 1996. An obituary of Wallace Carothers' important colleague.
• Nylon: Mere Miracle; An Explanation of How It's Made And How Chemists Discovered It by Elizabeth M. Fowler. The New York Times, January 11, 1959. A historic article from the Times marking 20 years of nylon.
• New Nylon Fiber Found: Strong, Warm Fabrics Believed Possible From Product: The New York Times, November 23, 1946. This article from the Times archive hails the discovery of a revolutionary new type of nylon.

Books

• Giant Molecules: From Nylon to Nanotubes by Walter Gratzer. Oxford University Press, 2011. Where do huge polymers come from and what can we do with them?
• Nylon and Bombs: DuPont and the March of Modern America by Pap A. Ndiaye. Johns Hopkins University Press, 2007. How DuPont's development of nylon and plutonium turned the 20th century into the plastics and nuclear age.
• Enough for One Lifetime: Wallace Carothers, Inventor of Nylon by Matthew Hermes. Washington, DC: American Chemical Society/Chemical Heritage Foundation, 1996. This definitive biography of Wallace Carothers is quite hard to track down but it's well worth a read if you can find it.
• Nylon and Bombs: DuPont and the March of Modern America by Pap A. Ndiaye, Johns Hopkins University Press, 2007. How DuPont's chemical innovations played a key part in 20th-century American dominance.
• Nylon: The Story of a Fashion Revolution by Susannah Handley. Johns Hopkins University Press, 1999.

Patents

If you're really interested, and your knowledge of chemistry is reasonably advanced, you'll find Wallace Carothers' patents for polyamides worth a look:

• US Patent 2,071,250: "Linear condensation polymers": In this patent (granted February 16, 1937), Carothers describes the chemistry behind "high molecular weight linear superpolymers having unusual and valuable properties".
• US Patent 2,130,523: "Linear polyamides suitable for spinning into strong pliable fibers": A follow-up patent on making nylon fibers, granted on September 20, 1938.

References

1. ↑   There are dozens of different types of nylon. The index of Polymers: A Property Database (by Ray Smith, CRC Press, 2008) refers to about 50 types.
2. ↑   Wheels in the Sky, NASA, May 25, 2000.
3. ↑   Innovating with renewable materials, DuPont, January 2023.
4. ↑   For an explanation of tensile strength, density, and tenacity, and how they relate to one another, see "Properties of Fibers" in Survey of industrial chemistry by Philip J. Chenier, Springer, 2002, p.318.
5. ↑   I used multiple sources for this chart, including Engineering Toolbox: Young's Modulus, Tensile Strength and Yield Strength Values for some Materials, Wikipedia: Specific strength, and double-checked in engineering data books. The values for concrete and bone are measured in compression.