Nylon 6,6 is made of hexamethylenediamine and adipic acid, which give nylon 6,6 a total of 12 carbon atoms, and its name.
Physical properties
- Nylon 6,6 has a melting point of 265°C, high for a synthetic fiber, though not a match for polyesters or aramids such as Kevlar. This fact makes it the most resistant to heat and friction and enables it to withstand heatsetting for twist retention.
- Its long molecular chain results in more sites for hydrogen bonds, creating chemical “springs” and making it very resilient.
- It has a dense structure with small, evenly spaced pores. This means that nylon 6,6 is difficult to dye, but once dyed it has superior colorfastness and is less susceptible to fading from sunlight and ozone and to yellowing from nitrous oxide.
Manufacture
- Hexamethylene diamine and adipic acid are combined with water in a reactor. This produces nylon salt. The nylon salt is then sent to an evaporator where excess water is removed.
- The nylon salt goes into a reaction vessel where a continuous polymerization process takes place. This chemical process makes molten nylon 6,6.
- The molten nylon 6,6 undergoes a spinning process, where the nylon 6,6 is extruded and sent through a spinneret, which is a small metal plate with fine holes. The nylon is then air-cooled to form filaments.
- Nylon's chemical formula is nHOOC-(CH2)4-COOH+n H2N-(CH2)6-NH2---->[-OC-( CH2)4-CO-NH-(CH2)6-NH-] n+2nH2O and the part -CO-NH- will stick together becoming Nylon 6,6.
Applications
- Carpet fiber
- Apparel
- Airbags
- Tires
- Ropes
- Conveyor Belts
- Hoses
Nylon 6,6's longer molecular chain and denser structure qualifies it as a premium nylon fiber, specified most often by professional architects and designers for use in commercial settings like offices, airports, and other places that get a lot of wear and tear. It is also an excellent choice for residential carpet applications.
