What is Nylon 66 ?
Created in 1930 by Wallace Hume Caruthers, Nylon is used for a variety of products because of its heat resistance and toughness at both high and low temperatures. However, both Nylon 6 and Nylon 6,6 (also called Nylon 6,6) differ in their uses and chemical properties, making each Nylon suitable for certain industries and products.
Nylon 66 (aka nylon 66, nylon 6/6 or nylon 6,6) is a type of polyamide or nylon. Nylons come in many types, and the two most common for textile and plastics industries are nylon 6 and nylon 66. Nylon 66 is made of two monomers each containing 6 carbon atoms, hexamethylene diamine and adipic acid, which give nylon 66 its name.
Nylon 66 is synthesised by polycondensation of hexamethylene diamine and adipic acid. Equivalent amounts of hexamethylene diamine and adipic acid are combined with water in a reactor. This is crystallized to make nylon salt, which has precisely stoichiometric equivalents. The nylon salt goes into a reaction vessel where polymerization process takes place either in batches or continuously. Removing water drives the reaction "n HOOC-(CH2)4-COOH + n H2N-(CH2)6-NH2→ [-OC-( CH2)4-CO-NH-(CH2)6-NH-]n + 2n H2O" toward polymerization through the formation of amide bonds from the acid and amine functions. Thus molten nylon 66 is formed. It can either be extruded and granulated at this point or directly spun into fibres by extrusion through a spinneret(a small metal plate with fine holes) and cooling to form filaments.
Nylon 6 VS Nylon 66
Both Nylon 6 and Nylon 6,6's polyamide chains are held together using hydrogen bonds, adding to the strength and dexterity of the fibers. Nylon 6's crystal structure contains parallel chains with hydrogen bonds between each chain, forming a more open structure with less internal hydrogen bonding. Compared to Nylon 6's crystal structure, Nylon 6,6 is tighter with less openings, making it the stronger and more resistant to heat of the two Nylons. Since Nylon 6,6's structure contains no set direction it makes the surface 12 percent harder and 20 percent more resilient than Nylon 6.
Differences in Properties
Both Nylon 6,6 and Nylon 6 are 100 percent elastic while under an 8 percent extension. However, both differ in their melting points, with Nylon 6 melting at 216 degrees Celsius and Nylon 6,6 having a me lting point of 263 degrees Celsius. This makes Nylon 6,6 the preferred Nylon for temperature performance products. Both Nylon 6 and 6,6 allow easy dyeing and washing and both provide a chemically s table product.
Each Nylon is preferred over the other in certain cases due to physical properties. For example, Nylon 6,6 is preferred over 6 for making carpets because of its higher strength and toughness. Nylon 6 is primarily used in the textile industry for making clothing, ropes, threads, nets and garments while Nylon 6,6 is used for tire ropes, gear wheels, friction bearings and plug parts.
The future of Nylon 66
Nylon 66 is a derivative of nylon synthesized by polycondensation of hexamethyelenediamine and adipic acid. It has superior mechanical properties and high heat resistance as compared to nylon 6. Nylon 66 can be reinforced with fillers, impact modifiers, fibers and internal lubricants to improve its physical properties such as strength, stiffness, ductility, friction properties and wear resistance. Nylon 66 is used for electro-insulating material, various machine parts, ball bearing cages, pipes, airbags, tires, ropes, conveyor belts, carpets fibers and apparel. End user industries of nylon 66 include automotive, industrial, consumer goods and electronics & electrical. Properties such as toughness, resistance to chemicals and high temperature, good appearance and processing flexibility makes nylon 66 suitable for various engineering applications.