Nylon Fiber: Properties, Advantages and Disadvantages

Nylon Fiber

What is Nylon Fiber?

Nylon fiber is a family of synthetic polymers, made up of repeating units linked by amide bonds. This material is versatile, as it’s a thermoplastic with a smooth, silky texture, allowing it to be melted and shaped into fibers, films, or different forms. Nylon polymers often include various additives to give them a wide range of properties. Nylon polymers are crucial in making fabrics. They are also important in various types of textile fibers, like those used in clothing, flooring, and strengthening rubber. Additionally, nylon fiber is molded into various shapes for applications such as making automotive parts and electrical equipment.

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The Science of Nylon

The term nylon fiber refers to a group of linear polyamides. There are two approaches to creating nylon for making fibers. In the first method, molecules with an acidic group (COOH) at each end react with molecules that have amino (NH2) groups at each end. The resulting type of nylon is named based on the number of carbon atoms between the two acidic groups and two amines. For example, nylon 6,6, made from adipic acid and hexamethylenediamine, is frequently used in fiber production. Nylon molecules are fairly flexible, with weak forces like hydrogen bonds between the polymer chains. To create strong fibers, the polymer must be heated and drawn out. The combination of two compounds in an exact 1:1 ratio of acid to base is known as “nylon salt.” This salt is then dried and heated under a vacuum to remove water and create the polymer. In the second method, a compound with an amine at one end and an acid at the other end is polymerized to produce a chain with repeating units of −NH−[CH2]n−CO−)x. If n equals 5, it’s called nylon 6, another common form of this polymer. Commercial production of nylon 6 starts with caprolactam, using an open-ring polymerization process. In both methods, the polyamide is melted and then drawn out after cooling to achieve the desired properties for the intended use. In the 1930s, a research team led by American chemist Wallace H. Carothers, working for E.I. du Pont de Nemours & Company, developed nylons. The successful production of fiber through chemical synthesis using compounds readily available from air, water, coal, or petroleum prompted further research into polymers, leading to the rapid expansion of synthetic materials.

Types of Nylon

There are eight types of nylon fiber, such as Nylon 6, Nylon 6,6, Nylon 4,6, Nylon 6,9, Nylon 6,10, Nylon 6,12, Nylon 11, and Nylon 12.

Here are a few examples:

  • Nylon 6, developed by Paul Schlack, is made using a ring-opening polymerization method.
  • Nylon 510 is derived from sebacic and pentamethylene diamine acid.
  • Nylon 1,6 is produced from dinitriles with the use of acid catalysis.
  • Nylon 66, discovered by Wallace Carothers, was patented using amide in its production process.

Physical Properties of Nylon Fiber

  • Tenacity: Dry strength ranges from 4 to 9 gm/den, with wet strength reaching 90% of the dry strength.
  • Elasticity: Typically stretches by 20-40% before reaching the breaking point.
  • Stiffness: Falls within the range of 20 to 40 gm/den.
  • Moisture regains: Approximately 3.5-5%, although it’s not highly absorbent due to its crystalline structure.
  • Specific gravity: Around 1.14.
  • Abrasion resistance: Demonstrates excellent durability against wear and tear.
  • Dimensional stability: Shows good resistance to changes in shape or size.
  • Resiliency: Exhibits an excellent ability to bounce back.
  • Softening point: Nylon 6,6 softens at 229°C, while Nylon 6 softens at 149°C.
  • Melting point: Nylon 6,6 has a melting point of 252°C, whereas Nylon 6 melts at 215°C.
  • Hand feel: Known for its soft and smooth texture.

Chemical Properties of Nylon Fiber

  • Acid: Nylon 6,6 is highly vulnerable to mineral acids and can dissolve when exposed to them. However, it remains unreactive to dilute acetic and formic acids, even when heated. Concentrated formic acid can dissolve Nylon 6,6. Nylon 6 is also sensitive to mineral acids but can withstand mild boiling organic acids.
  • Bleaches: Nylon fiber is generally resistant to damage from both oxidizing and reducing bleaches, but it may be negatively impacted by chlorine and strong oxidizing bleaches.
  • Alkali: Nylon is notably resistant to alkalis.
  • Organic Solvent: Most solvents have little to no effect on nylon. However, phenol, metacresol, and formic acid can dissolve the fiber. Fortunately, the solvents commonly used for stain removal and dry cleaning do not harm it.
  • Light: Nylon does not change color when exposed to light. Nonetheless, Nylon 6 gradually loses strength when exposed to prolonged light.
  • Biological: Nylon is not susceptible to damage from microorganisms or moth larvae.
  • Electrical: Nylon has high insulating properties, which can result in the accumulation of static charges on the fiber.
  • Flammability: Nylon burns slowly.

Advantages of Nylon Fiber

  • Strength: Nylon possesses exceptional tensile strength, making it a prime choice for applications like ropes, gears, and machinery components. Its robust resistance to abrasion also renders it well-suited for situations where wear and tear are a concern.
  • Versatility: Nylon fiber can take on various forms, including fibers, films, and moldings. Its ease of color customization proves advantageous for products that necessitate consistent coloration, like clothing and textiles.
  • Durability: Nylon’s remarkable resistance to wear and tear makes it an outstanding option for products subjected to frequent and prolonged use. This durability is especially valuable for applications that require enduring performance, such as gears, ropes, and backpacks.
  • Moisture Resistance: Nylon exhibits impressive resistance to moisture, making it a perfect choice for products exposed to water or other liquids. It is frequently utilized in outdoor gear, clothing, and applications that prioritize hygiene, such as medical devices and packaging.
  • Chemical Resistance: Nylon can withstand a broad array of chemicals, including acids and bases. This property finds utility in laboratory equipment and industrial products.
  • Lightweight: Nylon’s lightweight nature is pivotal for reducing weight in applications such as aircraft and automotive parts, as well as gear, ropes, and backpacks.
  • Ease of Processing: Nylon is easily processed and can be molded into intricate shapes and designs. This characteristic diminishes the need for additional machining or assembly processes, resulting in a cost-effective solution.

Disadvantages of Nylon Fiber

  • Cost: Nylon can be more expensive than other synthetic materials like acetate, acrylic, lyocell, microfiber, and similar options.
  • Hydrolysis: Nylon is vulnerable to hydrolysis, a chemical reaction that causes it to deteriorate in the presence of moisture. This degradation can lead to a decrease in nylon’s strength and durability over time, making it less suitable for long-term applications or use in moist environments.
  • UV Sensitivity: Nylon is sensitive to ultraviolet (UV) light and may degrade when exposed to sunlight. This makes it a less ideal choice for outdoor applications.
  • Limited Temperature Resistance: Nylon has restricted resistance to high temperatures, and it may deform or lose strength when exposed to heat. Therefore, it’s not the best option for high-heat applications, such as electrical insulation.
  • Flammability: Nylon is a flammable material and can catch fire easily. For safety reasons, consider alternative materials that are less prone to ignition.
  • Environmental Impact: Nylon fiber production consumes a significant amount of energy and can have detrimental effects on the environment. It also contributes to the accumulation of plastic waste in natural surroundings.

Uses of Nylon

Apparel: High-tenacity nylons have a range of applications in the clothing industry. They are used to make parachute fabrics, cords, and ropes. These nylons are valued for their excellent dimensional stability, making them a great choice for producing items like women’s gloves, hosiery, underwear, swimwear, stockings, and hosiery fabrics.

Household: Nylon is a popular material for various household items, such as carpets and upholstery. It is also employed in the construction of ropes and cords for various domestic purposes.

Industrial Applications: Nylon plays a vital role in industrial settings, with uses in finishing nets, tire cords, filtering cloths, sewing threads, and tow ropes. It is also used in the production of belts for various types of machinery, including flat belts and V-belts.

Nylon Fiber: Properties, Advantages and Disadvantages
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