Six Key Properties of Nylon Fiber

1. Abrasion Resistance

Nylon and polyester share many similar properties. However, nylon has lower heat resistance and a lower density, while it absorbs more moisture and is easier to dye. Its strength, abrasion resistance, and fatigue resistance are generally better than those of polyester.

Nylon can deform more easily, but it also shows good recovery and high resilience. Its initial modulus is about two to three times lower than polyester. Therefore, under the same stress, nylon has lower elasticity than polyester.

Nylon’s high elongation gives it excellent resistance to impact and abrasion. Among common textile fibers, nylon offers outstanding abrasion resistance. Its abrasion resistance can be about 10 times higher than cotton and 20 times higher than wool.

Table 1. Abrasion Cycles Before Fiber Breakage

2. Low Density

Among major synthetic fibers such as polyester, nylon, acrylic, and vinylon, nylon has the lowest density, at approximately 1.14.

Because nylon is lightweight and strong, it works well in materials for high-altitude and mountain operations. It is also suitable for ropes, fishing nets, fine yarns, and hollow fibers.

3. Thermal Properties

During nylon processing, temperature control plays an important role.

When nylon remains in hot air above 100°C, its strength can decrease noticeably. Oxidative chain degradation causes this loss. However, heating nylon without oxygen causes much less damage.

In general, nylon retains higher strength at lower temperatures. Lower temperatures reduce molecular movement and strengthen the forces between molecules.

At room temperature, nylon staple fiber can reach a strength of approximately 57.33–66.15 cN/tex. Nylon filament yarn can reach about 83.8 cN/tex, which is two to three times stronger than cotton fiber.

As the temperature rises, nylon begins to shrink. Near its melting point, the shrinkage becomes severe, and the fiber may turn yellow.

Table 2. Heat Resistance of Nylon

4. Electrical Properties

Nylon has low electrical conductivity, so friction during production can easily create static electricity.

However, conductivity increases significantly as relative humidity rises. For example, when relative humidity increases from 0% to 100%, the conductivity of Nylon 66 can increase by approximately one million times.

Therefore, spraying or other moisture-conditioning treatments during processing can help reduce static buildup in nylon fabrics.

5. Moisture Absorption and Dyeing Performance

Nylon is generally considered a hydrophobic fiber. However, its molecular structure contains many weakly hydrophilic amide groups, as well as hydrophilic amino and carboxyl groups at both ends of the molecular chain.

As a result, nylon absorbs more moisture than most synthetic fibers, with vinylon as a notable exception. Nylon 6 usually absorbs slightly more moisture than Nylon 66 because it contains a small amount of residual low-molecular-weight material.

Table 3. Moisture Regain of Common Fibers at 65% Relative Humidity and 20°C

When nylon absorbs moisture, the fiber expands. Unlike many other fibers, nylon shows relatively little difference between its longitudinal and transverse expansion.

The fiber surface limits expansion across the cross-section, while the amorphous regions allow greater movement along the fiber length. Consequently, nylon fabrics may become slightly longer after absorbing moisture.

Nylon does not dye as easily as natural fibers. Still, among synthetic fibers, it has relatively good dyeability.

The nylon molecule contains hydrophobic methylene chains, so disperse dyes can be used. It also contains terminal amino and carboxyl groups, as well as imino groups within the molecular chain.

Nylon has dyeing characteristics similar to wool. In an acidic bath, nylon becomes positively charged and can be dyed with anionic dyes. In an alkaline bath, it becomes negatively charged and can accept cationic dyes.

However, these dyeing methods may result in lower soap-washing and light fastness. Therefore, they are used less frequently.

6. Chemical Properties

Nylon has good chemical stability, especially strong resistance to alkalis.

For example, when treated in a 10% sodium hydroxide solution at 85°C for 10 hours, nylon loses only about 5% of its strength.

However, the amide groups in nylon can hydrolyze under certain conditions. Acids may hydrolyze the molecular chains and reduce the degree of polymerization. Hot water above 150°C can also cause hydrolysis.

Both acids and heat accelerate this process.

Strong oxidizing agents can damage nylon. Bleaching powder, sodium hypochlorite, and hydrogen peroxide may break the molecular chains and reduce fiber strength. These chemicals may also cause the fabric to turn yellow after bleaching.

When nylon requires bleaching, manufacturers generally choose sodium chlorite or a reducing bleach instead.

Conclusion

Nylon combines high strength, excellent abrasion resistance, light weight, good resilience, and relatively good dyeability. These properties make it suitable for apparel, hosiery, sportswear, industrial textiles, ropes, fishing nets, and many other products.

However, nylon also requires careful temperature control and protection from strong oxidizing agents. By selecting suitable dyes, processing temperatures, and finishing methods, manufacturers can make better use of nylon’s performance while reducing the risk of shrinkage, yellowing, static buildup, and strength loss.