Commonly used nylon fibers can be divided into two categories.

Commonly used nylon fibers can be divided into two categories.

One is polydiamine diadiate obtained by polycondensation of diamine and diacid, and the chemical structure formula of its long chain molecule is:

H-[HN(CH2)xNHCO(CH2)yCO]-OH

The relative molecular weight of this kind of nylon is generally 17000-23000. Different nylon products can be obtained according to the different number of carbon atoms of binary amine and diacid used, and can be distinguished by the number added to the nylon, where the first number is the number of carbon atoms of binary amine and the last number is the number of carbon atoms of diacid. For example, polyamide 66 is made of hEXAMethylenediamine and adipic acid. Polyamide 610, indicating that it is made from hexamethylene diamine and sebacic acid.

The other is obtained by polycondensation or ring-opening polymerization of lactam, and the chemical structural formula of its long chain molecules is:

H-[NH(CH2)xCO]-OH