Polyamide commonly known as nylon (Nylon), English name Polyamide (referred to as PA), is the molecular main chain containing repetitive amide group-[nhco]-of thermoplastic resins collectively. including Aliphatic PA, fat-aromatic pa and aromatic pa. Among them, the aliphatic pa varieties, the production of large, widely used, its name by the synthesis of the specific number of carbon atoms determined. It is the first synthetic fiber in the world developed by Carothers, a distinguished scientist in the United States, and a team of scientists led by Carothers. The appearance of nylon makes the appearance of textiles a brand-new, its synthesis is a major breakthrough in the synthetic fiber industry, but also is an important milestone of polymer chemistry.