science

Nylon 6

Nylon 6 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nylon 6 rather than just read about it. In short: Nylon 6 or polycaprolactam is a polymer, in particular semicrystalline polyamide. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization; this makes it a special case in the comparison between condensation and addition polymers.

Key takeaways

Nylon 6 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nylon 6 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nylon 6 from memory before moving on to harder problems.

Reference excerpt

Nylon 6 or polycaprolactam is a polymer, in particular semicrystalline polyamide. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization; this makes it a special case in the comparison between condensation and addition polymers. Its competition with nylon 66 and the example it set have also shaped the economics of the synthetic fibre industry. It is sold under numerous trade names including Perlon (Germany), Dederon (former East Germany), Nylatron, Capron, Ultramid, Akulon, Kapron (former Soviet Union and satellite states), Rugopa (Turkey) and Durethan.

History Polycaprolactam was developed by Paul Schlack at IG Farben in late 1930s (first synthesized in 1938) to reproduce the properties of Nylon 66 without violating the patent on its production. (Around the same time, Kohei Hoshino at Toray also succeeded in synthesizing nylon 6.) It was marketed as Perlon, and industrial production with a capacity of 3,500 tons per year was established in Nazi Germany in 1943, using phenol as a feedstock. At first, the polymer was used to produce coarse fiber for artificial bristle, then the fiber quality was improved, and Germans started making parachutes, cord for aircraft tires and towing cables for gliders. The Soviet Union began its development of an analog in the 1940s, while negotiating with Germany on building an IG Farben plant in Ukraine, basic scientific work was ongoing in 1942. The production only started in 1948 in Klin, Moscow Oblast, after USSR obtained the 2000 volumes of IG Farben, and 10,000 volumes of AEG technical documentation, as a result of victory in World War II.

Synthesis Nylon 6 can be modified using comonomers or stabilizers during polymerization to introduce new chain end or functional groups, which changes the reactivity and chemical properties. It is often done to change its dyeability or flame retardance. Nylon 6 is synthesized by ring-opening polymerization of caprolactam. Caprolactam has 6 carbons, hence Nylon 6. When caprolactam is heated at about 533 K in an inert atmosphere of nitrogen for about 4–5 hours, the ring breaks and undergoes polymerization. Then the molten mass is passed through spinnerets to form fibres of nylon 6.

During polymerization, the amide bond within each caprolactam molecule is broken, with the active groups on each side re-forming two new bonds as the monomer becomes part of the polymer backbone. Unlike nylon 6,6, in which the direction of the amide bond reverses at each bond, all nylon 6 amide bonds lie in the same direction (see figure: note the N to C orientation of each amide bond).

Properties Nylon 6 fibres are tough, possessing high tensile strength, elasticity and lustre. They are wrinkleproof and highly resistant to abrasion and chemicals such as acids and alkalis. Nylon 6 is hygroscopic, absorbing up to 2.4% of its weight in water. This has a significant effect on its properties, greatly decreasing the modulus and yield stress but increasing the ductility. The glass transition temperature of Nylon 6 is 47 °C. As a synthetic fibre, Nylon 6 is generally white but can be dyed in a solution bath prior to production for different color results. Its tenacity is 6–8.5 gf/D with a density of 1.14 g/cm3. Its melting point is at 215 °C and can protect heat up to 150 °C on average.

Biodegradation Flavobacterium sp. [85] and Pseudomonas sp. (NK87) degrade oligomers of Nylon 6, but not polymers. Certain white rot fungal strains can also degrade Nylon 6 through oxidation. Compared to aliphatic polyesters, Nylon 6 has been said to have poor biodegradability. Strong interchain interactions from hydrogen bonds between molecular nylon chains is said to be the cause by some sources. However, in 2023 a team of Northwestern University chemists led by Linda Broadbelt and Tobin J. Marks developed rare earth metallocene catalysts that rapidly break Nylon 6 down back to caprolactam at 220 °C, which is considered mild conditions.

Production in Europe At present, polyamide 6 is a significant construction material used in many industries, for instance in the automotive industry, aircraft industry, electronic and electrotechnical industry, clothing industry and medicine. Annual demand for polyamides in Europe amounts to a million tonnes. They are produced by all leading chemical companies. The largest producers of polyamide 6 in Europe:

Fibrant, 260,000 tonnes per year BASF, 240,000 tonnes per year Lanxess, 170,000 tonnes per year Radici, 125,000 tonnes per year DOMO, 100,000 tonnes per year Grupa Azoty, 100,000 tonnes per year

References

Illustrations

Worked examples

Example 1 — a first encounter with Nylon 6

Start with the simplest possible case. Write down what Nylon 6 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nylon 6 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nylon 6 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nylon 6

In research: Nylon 6 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nylon 6 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nylon 6 is common in secondary-school and first-year university syllabi. It links to neighbouring topics German inventions of the Nazi period, Plastics, Polyamides, so understanding it makes those chapters shorter.
In everyday life: Look for Nylon 6 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Nylon 6 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nylon 6 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nylon 6 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nylon 6 in simple terms?

Why does Nylon 6 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nylon 6?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nylon 6.