1, one is poly (hexamethylene adipate) obtained by polycondensation of diamine and diacid, and the chemical structural formula of its long chain molecule is:
Hydrogen -[HN(CH2)XNHCO(CH2)YCO]- Oh
The relative molecular weight of this nylon is generally 17000-23000. According to the different carbon numbers of diamines and diacids, different nylon products can be obtained, which can be distinguished by the numbers added to nylon, where the former number is the carbon number of diamines and the latter number is the carbon number of diacids. For example, nylon 66 shows that it is formed by polycondensation of hexamethylenediamine and adipic acid; Nylon 6 10 is shown to be made of hexamethylenediamine and sebacic acid.
2. The other is obtained by polycondensation or ring-opening polymerization of caprolactam, and the chemical structural formula of its long-chain molecule is:
Hydrogen -[XCO]- oh
According to the number of carbon atoms in its unit structure, it can be named as different varieties. For example, nylon 6 shows that it is obtained by ring-opening polymerization of caprolactam containing 6 carbon atoms.
Aliphatic nylons such as nylon 6 and nylon 66 are all composed of linear macromolecules with amide bond (-NHCO-). There are -CO- and -NH- groups in nylon molecules, which can form hydrogen bonds between molecules or combine with other molecules, so nylon has good moisture absorption ability and can form a better crystal structure.
Extended data
The main chain of polyamide contains many repeated amide groups, which are called nylon when used as plastics and nylon when used as synthetic fibers. Polyamide can be made of diamines and diacids, and can also be synthesized from omega-amino acids or cyclic lactams. According to the number of carbon atoms in diamines, diacids or amino acids, many different polyamides can be prepared, and there are dozens of kinds of polyamides, among which polyamide -6, polyamide -66 and polyamide -6 10 are the most widely used.
The chain structures of polyamide -6, polyamide -66 and polyamide -6 10 are [NH(CH2)5CO], [NH(CH2)6NHCO(CH2)4CO] and [NH(CH2)6NHCO(CH2)8CO] respectively. Polyamide -6 and polyamide -66 are mainly used for spinning synthetic fibers, which are called nylon -6 and nylon -66. Nylon 6 10 is a kind of thermoplastic engineering plastic with excellent mechanical properties.
PA has good comprehensive properties, including mechanical properties, heat resistance, wear resistance, chemical resistance and self-lubrication, and has low friction coefficient, certain flame retardancy and processability. It is suitable for reinforcing and modifying filled glass fiber and other fillers, improving performance and expanding application range.
There are many varieties of PA, such as PA6, PA66, PAll, PA/KOOC-0/2, PA46, PA6/KOOC-0/0, PA6/KOOC-0/2, PA/KOOC-0/0, and semi-aromatic nylon PA6T and KOOC-0/0 developed in recent years. Using metal sodium and sodium hydroxide as main catalysts and n-acetylcaprolactam as cocatalyst, δ-caprolactam can be directly polymerized by negative ion ring opening in the model, and nylon -6 plastic products can be made, which is called cast nylon.