Polyamide is a polyamide fiber trade name, also known as NYLON (Nylon), nylon-6. English name Polyamide (referred to as PA), the basic composition of the material is amide bond - [NHCO] - linked to the aliphatic polyamide Many of these properties can be enhanced by the addition of fillers such as molybdenum disulphide. Nylons are resistant to hydrocarbons,alkalies,ketones and esters. These Polyamides, commonly referred to as Nylon and available in Sheets, Rod and Tube and are distinguished by different types. The most common engineering Nylons are PA 6 and PA 66. Nylon stock shapes are produced by either extrusion or casting. The process is in part a determinant of the nylon properties of the end product. Modifiers are added to enhance desirable characteristics.