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Polyamide fibers are synthetic fibers used in the manufacture of textiles. International Polyamid is often called nylon. Originally nylon was a brand that was launched by the fiber manufacturer DuPont in 1938 but is now used to refer to polyamide fibers in general.
The most common polyamide is polyamide 66 (Polyamide), whose starting monomers, adipic acid and hexamethylene diamine. A similar variant is prepared by adding the reaction of caprolactam and the result is called polyamide 6 or perlon. There are a variety of polyamides with varying numbers of carbon atoms of monomers. The usual polyamide fibers are produced by melt spinning processes with additives of matting agents, optical brightening agents and catalysts. Later versions of the polyamides are the so-called aramids. These are made of aromatic diacids and diamines. They have very high melting points and therefore cannot be melted by spinning processes. They must be spun from solutions. The fiber class aramids include Nomex are often used in firefighter’s uniforms, and Kevlar. Kevlar has, in addition to flame retardant materials, also reinforcing properties and is used instead of fiberglass where light weight is a requirement. Environmental impact
The major environmental impact in the preparation of polyamide fibers is the high consumption of energy, both as raw materials (oil) and the melt-spinning. Polyamide is normally produced by melt spinning and low emissions are found when spinning. As in polyester production one must use spinning oils which will later be washed out before staining and finishing. Normally no dyes or flame retardants are added in melt spinning of polyamide, since they can leach out of the fibers during washing (cf. polyester where the substances are not leached out). The aramids are spun from a solution because of their high melting point which results in that you cannot spin them from a melted state. Sources Textilmiljöhandboken