A kind of thermoplastic resin contains amide groups (-conh-) in the repeating structural units of nylon molecular skeleton, including aliphatic polyamides, aliphatic-aromatic polyamides and aromatic polyamides. Aliphatic polyamides have many varieties, large output and wide applications, and can be used as fibers and plastics. Aliphatic-aromatic polyamides have few varieties and small output. Aromatic polyamide is usually referred to as polyaramid for short, and is mainly used as fiber (aramid fiber).
Aliphatic nylon is divided into nylon 6, nylon 66, nylon 10 10, etc.
In fact, there is not much difference between nylon 6 and nylon 66. They are all produced because other companies invented nylon 6 in order to produce nylon, and because DuPont applied for a patent after the invention. Nylon is the most common artificial fiber. 1940 stockings woven with nylon were very popular when they came out, and nylon became famous at one fell swoop. Since then, during World War II, nylon has been widely used to weave parachutes and ropes. However, nylon was originally used.
Nylon belongs to polyamide and has amino groups in its main chain. Amino groups are polar and attract each other because of hydrogen bonds. So nylon is easy to crystallize and can be made into high strength fibers. Polyamide is a tough horny translucent or ivory crystalline resin, which is often made into cylindrical particles. The molecular weight of polyamide for plastics is generally1.5,000 ~ 20,000.
The common characteristics of all kinds of polyamides are flame retardancy, high tensile strength (up to 104MPa), wear resistance, good electrical insulation, heat resistance (thermal deformation temperature at 455kPa is above 150℃), melting point 150 ~ 250℃, high fluidity of molten resin and relative density of 65433.