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Did You Know?
The names of the types of polyamides are derived from the number of carbon atoms in their molecules. This number is used as a suffix to the name.
When amide monomers are connected together by peptide bonds to form polymers, it is known as a polyamide. Some of the naturally occurring polyamides are silk, wool, and proteins.

Polyamides are classified into two categories. Aliphatic polyamides, known as nylons, and aromatic polyamides, known as aramids. We will now discuss the types of polyamides and their uses.

Aliphatic Polyamides (Nylon Class)

Nylon 6, 6 or PA 66
It has a high melting point and a great abrasion resistance. Therefore, it is preferred in making parts of machines. Some of its disadvantages are that it has a poor chemical resistance and high water absorption. It is the most popularly used thermoplastic material due to its extreme heat resistance and strength. It is used in making carpet fibers, electro-insulating elements, bearings, gears, and conveyor belts. It has good elasticity and a high mechanical strength.

Nylon 6 or PA 6
It is a semi-crystalline polyamide characterized by ductility and resistance to abrasion. It is used to develop non-woven fabrics. These fabrics are easy to dye and are lustrous. Strings of sitars, violins, and other similar instruments are made of nylon 6. It is also used for making threads, nets, ropes, and knitted garments.

Nylon 6, 10 or PA 610
It is used as mono-filaments. This polymer is used in making filaments of brushes, electric insulators, hosiery, and zip fasteners. It is resistant to chemicals and mineral acids. Nylon 6, 10 is stronger than most other nylons. It does not crack under the effect of salts like zinc chloride. Also, because of its low-moisture absorption properties, it holds on its qualities better, when wet.

Nylon 11 or PA 11
Although it is derived from vegetable oil, it is not biodegradable. It is used in making mechanical components, automotive-fuel lines, sports shoes, tool handles, gears, hydraulic fluid, and powder coatings. It is not resistant to concentrated acids and halogens. As compared to other nylons, it has a better resistance to UV. During production, it uses lesser renewable resources than nylon 12. Owing to its resilient property, it is mainly used in the production of flexible pipes for oil and gas.

Nylon 6, 12 or PA 612
It is expensive than most other nylons. It does not abrade to heat, but its resistance to strong acids and bases is poor. Nylon 6, 12 has a lower rate of water absorption than nylon 6 and nylon 6, 6. It is used in making electrical components, gears, cams, seals for spark plug tubes, and lock casings, and has a great dimensional stability.

Nylon 12 or PA 12
It can be easily worked into any shape or size. Its resistance to wearing out is so high that even when subjected to high-frequency cyclical load, this polyamide is not affected. When compared to other nylons, this nylon is expensive. It is not as popular as other nylons; however, it is used in making cable fasteners, sheet gaskets, sealing rings, protective coverings, diaphragms, and ski boots. Similar to nylon 11, it is highly flexible, and hence used in making pipes used in automobiles and air ducts.

Nylon 6, 9 or PA 69
It has a low melting point and a lower moisture absorption than other polyamides. It is used for making electrical connectors, banners, luggage bags, furniture, and automotive upholstery.

Nylon 4, 6 or PA 46
As compared to other polyamides, this is the most fatigue-resistant of all. Its thermal dimensional stability is high. Nylon 4, 6 is better in chemical resistance and crystallizing than nylon 6 and nylon 6, 6. Where other nylons fail to perform, this nylon retains its properties at raised temperatures. Its applications are similar to other nylons and it is used in electronic and electrical components.

Aromatic Polyamides

Aramid
It is also known as aromatic polyamide. Some of its applications are hot-air filtration fabrics, optical-fiber cable, heat-protective clothing, helmets, jet-engine enclosures, loudspeaker diaphragms, and reinforced-thermoplastic pipes. Aramids are non-conductive, but are sensitive to UV. They provide good resistance to organic solvents and abrasion.

Polyphthalamide
Polyphthalamide is a semi-aromatic polyamide. Compared to other polyamides, polyphthalamide is not only stiffer, but also more creep-resistant. It has high resistance to heat, chemicals, and abrasion. Some of the areas it is used include valves in showers, air coolers, bearing pads in aircraft engines, motor insulators, and other electronic connectors.

Other than the many applications of polyamides, they are much superior to other plastics. Because polyamides can be recycled and reused in many ways, they are the first choice in engineering applications.