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A polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solid-phase synthesis, examples being nylons, aramids, and sodium poly(aspartate). Polyamides are commonly used in textiles, automotives, carpet and sportswear due to their extreme durability and strength.
According to the composition of their main chain, polyamides are classified as follows:
|Polyamide family||Main chain||Examples of polyamides||Examples of commercial products|
|Aliphatic polyamides||Aliphatic||PA 6 and PA 66||Nylon from DuPont, Technyl from Rhodia, Rilsan and Rilsamid from Arkema|
|Polyphthalamides||Semi-aromatic||PA 6T = hexamethylenediamine + terephthalic acid||Trogamid from Evonik Industries, Amodel from Solvay|
|Aramides = aromatic polyamides||Aromatic||Paraphenylenediamine + terephthalic acid||Kevlar and Nomex from DuPont, Teijinconex, Twaron and Technora from Teijin, Kermel from Kermel, and Spectra from Honeywell.|
According to the number of repeating units' types, polyamides can be:
- homopolymers :
- copolymers :
- PA 6/66 : [NH-(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)5−CO]m made from caprolactam, hexamethylenediamine and adipic acid ;
- PA 66/610 : [NH−(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)6−NH−CO−(CH2)8−CO]m made from hexamethylenediamine, adipic acid and sebacic acid.
According to their crystallinity, polyamides can be:
- high crystallinity : PA46 et PA 66 ;
- low crystallinity : PA mXD6 made from m-xylylenediamine and adipic acid;
- amorphous : PA 6I made from hexamethylenediamine and isophthalic acid.
According to this classification, PA66, for example, is an aliphatic semi-crystalline homopolyamide.
Production from monomers 
The amino group and the carboxylic acid group can be on the same monomer, or the polymer can be constituted of two different bifunctional monomers, one with two amino groups, the other with two carboxylic acid or acid chloride groups.
Aramid (pictured below) is made from two different monomers which continuously alternate to form the polymer and is an aromatic polyamide:
Antistatic need 
These materials are commonly completely insulating, and generate static electricity, which can cause dangerous sparks that can damage electronics in manufacturing plants and in consumer products. This has resulted in an interest in incorporation of conductive fillers such as carbon black, metals and conducting polymers. The most common conducting fillers are silver and carbon black. Both of these materials have processing deficiencies, while silver is also prohibitively expensive for applications such as antistatics.