Because of nylon’s versatility, it is one of the most widely used engineering thermoplastics. Commercially available nylons include nylon 6, nylon 4/6, nylon 6/6, nylon 6/10, nylon 6/12, nylon 11 and nylon 12. The numerical nomenclature for nylon is derived from the number of carbon atoms in the diamine and dibasic acid monomers used to manufacture it. The ratio of carbon atoms is what gives each nylon type its unique property characteristics.
Nylon 6 is a tough, abrasion-resistant material. It has improved surface appearance and processability compared to nylon 6/6. It also can be molded about 80 degrees F (45 degrees C) lower with less mold shrinkage because it is slightly less crystalline. Adversely, nylon 6 has a lower modulus and absorbs moisture more rapidly than nylon 6/6. Moisture acts as a plasticizer, reducing tensile strength and stiffness and increasing elongation. But, while absorbed moisture reduces many properties, nylon owes part of its toughness to the plasticizing effect of moisture. As moisture content rises, significant increases occur in impact strength and general energy absorbing characteristics. Properly recognized and accounted for, the effect of moisture on the processing and properties of nylon need not be of great concern.
All nylons can be reinforced with glass fibers, glass beads, and carbon fibers to improve their mechanical and thermal performance. Filled materials containing PTFE and molybdenum disulphide are available for bearing materials with appropriately low friction and improved wear. Nylon 6 is used in applications where toughness, lubricity, and wear are important, such as gear wheels.