It is interesting that an error is behind the discovery of this very versatile plastic material, and one of the most well-known in our world today - Nylon®.

It was 1934 when the person who discovered it, Wallace Hume Carothers, an organic chemical researcher, made a mistake in an attempt to produce a synthetic fibre and instead obtained a synthetic silk.

He patented it in 1938 and, after his death, the DuPont company kept the patent and produced this strong and elastic synthetic fibre, which would replace, in part, silk and rayon.
This invention revolutionised the textile market just before the Second World War, and was used in the manufacture of tights, parachutes and ropes for war equipment.
But the first product manufactured with this synthetic fibre was a toothbrush with Nylon® bristles.

There are various versions of Nylon®, with what is called Nylon® 6 (PA6) being perhaps one of the most famous and widely used.

From the chemical point of view, Nylon® is a polymer from the polyamide family, it is semi-crystalline and has high wear resistance.

Polyamides are whitish industrial thermoplastics, generally synthesised from amines and linear chain aliphatic acids.

They have good tensile strength, meaning that they are resistant when stretched and generally have low compression strength, meaning that they are weak when squeezed or compressed (in another words, they can be considerably stretched, but they do not recover their original length).

The PA6.6 polyamide is another of the main polyamides, which is harder and more abrasion resistant with higher toughness at low temperatures than Nylon6® or acetal.

Its very low melt viscosity can lead to difficulties in industrial transformation, and its exposure to the weather can cause embrittlement and a colour change unless it has prior stabilisation or protection.

It is available with a wide range of fillers, especially glass fibre which provides a significant increase in rigidity.

In another post, I will talk about the various types of polyamide obtained as a consequence of modifying the chemical structures (length of chains and chemical organisation), such as PA11, PA12, PA4.6, etc.

 Nylon® is usually a solid, hard (but sensitive to nicking), fairly elastic polymer with good protective properties, high fatigue and good abrasion resistance.

However, its water absorption is significant (slow in thick sections), coupled with an increase of dimensions of up to 3% in some extreme circumstances.
It has good resistance to oils, fats, hydrocarbons, solvents and alkalis, but not to the acids that hydrolyse it.

It is very strong with good flexibility, it is a weldable and bondable material, with an electrical insulation behaviour/function.

It has ammonia, chlorinated water and potassium solution limitations.

Polyamides are characterised by their optimal mechanical properties, wear resistance, low coefficient of friction, high melting points, good impact resistance and high fatigue resistance.

 They also have excellent resistance to organic solvents, except in some cases such as formic acid.

They have no resistance to sulphuric, phosphoric, acetic acids and certain strong oxidising agents.

They can be easily moulded and are used to produce a wide range of dyed items.

They have excellent surface brightness.

 As you will have already realised, polyamides have excellent mechanical properties, although for this, internal stresses must be relieved first to prevent cracking during machining.
This is done by heating the Nylon® at high temperatures, close to melting point, for a few days until it stabilises.

This material, can come in the form of rods, round tubes, plates or thread as a semi-finished product.

Its applications include various industrial components in all sectors.
For example, gearboxes, bushes, nuts, rivets, wheels, bolts, and any type of profile.

They are also used as a monofilament for brushes, and the fibres are noted for their elasticity and their abrasion resistance for use in carpets and industrial applications.

In reality, Nylon® is one of the most versatile polymers in machining or injection processes.

It can take on a multitude of geometrical shapes based on a careful study of the properties required of the final part, according to compatibility between usage and technical, physical and chemical characteristics of the polyamide.

Once again, we can see the versatility of engineering plastics and be surprised by the number of applications where we can rely on plastic parts, as in this case – Nylon® can be found in anything from fine and elegant hosiery, to electrical insulation parts or powerful gears in the production lines of any industrial sector.

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