Nylon 6-6, also referred to as nylon 6,6, is a polyamide from nylon class. Nylons come in many types, and the two most common for textile and plastics industries are nylon 6 and nylon 6-6. The polymer is made of hexamethylenediamine and adipic acid, which give nylon 6-6 a total of 12 carbon atoms in each repeating unit, and its name.