what is polyamide

What is Polyamide Fabric?

What is Polyamide Fabric?

Firstly, we are going to answer one of the most important questions of the series, “What is Polyamide fabric? “. Polyamide fabric is a synthetic polymeric fabric formed by the condensation polymerization reaction of an amine (-NH2) and a carbonyl (C=O) containing monomer.

The repeating chains of these two monomers are linked together by an amide linkage. An amide functional group has the formula -CONH2. Polyamide fabric refers to a wide range of fabrics that are manufactured from monomers.

Structure of polyamide linkage
Structure of polyamide linkage

Common Commercial fabrics

The most common polyamide fabric is Nylon, Perlon, and Aramid, etc. DuPont ™ Corporation was the first company to manufacture this fabric in the mid-1930s. The main advantage offered by these fibers is their elasticity, but the customers have also ranked it as soft material.

Polyamide fabric is also known for its military applications. Kevlar, which is a type of Aramid Fabric, is used in bullet-proof jackets because it is light-weight, heat resistant, and stronger than steel.

With high mechanical strength, high heat resistance, wear-resistance, high elasticity and dimensional stability, Polyamide fabric have a wide variety of applications for example:

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  1. Parachutes
  2. Fine stockings
  3. Undergarments
  4. Carpets
  5. Outer sports garments
  6. Motorcycle garments

Unlike other fabrics (for instance Rayon and Viscose), these fabrics are easy to handle, these fabrics do not lose their strength when wet and can easily be ironed but they cannot be dry cleaned.

Types of Polyamide Fabric

There are two main types of these fabrics:

  1. Polyamide 6, this fabric is usually known as Perlon
  2. Polyamide 6, 6, this fabric is commonly known as Nylon

The number(s) after the term polyamide indicates the number of carbon atoms that are present in each molecule of the polymer.

Polyamide 6 structure - What is Polyamide Fabric
Polyamide 6 structure
Polyamide 6, 6 structure
Polyamide 6, 6 structure

Manufacturing Process

The monomers for the manufacturing of Polyamide fabric are commonly extracted from petroleum oil or crude oil. The origin of the monomers for these fibers shows that its manufacturing method cannot be an environmentally-friendly process as petroleum is one of the major sources of pollution. Petroleum oil is also the origin material for many other polymeric materials. This process of polyamide fabric manufacturing is known as a melt spinning process.

The monomers used for the production of fibers are hexamethylenediamine (HMD) and adipic acid (ADA). A chemical reaction takes place when these two monomers and water are added to a reaction vessel.

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Hexamethlene Diammonium adipate
Hexamethlene Diammonium adipate

The reaction yields Hexamethylene diammonium adipate, commonly referred to as the “nylon salt” solution. Water is evaporated and removed from the salt solution. After the removal of water, the salt is heated until it melts.

Other additives like a slurry of TiO2 pigments and water can be added to the salt to deluster the fibers. This molten salt polymerizes in the polymerization reactor to form polyhexamethylene adipamide. The polymerization step takes place at 275OC. It is then passed through a metal spinneret with a process called extrusion. The molten salt hardens as soon as it passes through the spinneret to form these fibers. These fibers are collected on a type of spool called a bobbin.

These fibers are then stretched to increase their elastic and mechanical properties. Then the molecules of the polymer are arranged in a parallel structure through a process called drawing. After drawing, these fibers are loaded onto another spool and are ready to be spun into fabric. In most applications, the polyamide fabric is blended with other fabrics to enhance its properties and applications.

Manufacturing process of polyamide fabric
Manufacturing process of polyamide fabric

During the extrusion process, the molten nylon salt is cooled by using a large quantity of water. This water is contaminated and needs to be disposed of safely. Production of polyamide fibers offers other environmental effects as well, for example, Nitrous oxide (N2O), which is a powerful greenhouse gas and contributes to the depletion of stratospheric ozone is produced during its manufacturing.

Moreover, the dust and fumes formed as by-products can irritate the nose, throat, and skin of a worker. Thus, amide manufacturing has a high impact on the environment as well as the workers working in production plants.

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Follow these articles for characterization of polyamide fabric and their processing;

  1. FTIR analysis of Aramid
  2. Thermal Analysis of Aramid
  3. Blending of Polyamide products to improve processability

Applications of Polyamide Fabric

After these amide fabrics are obtained, they are used for a wide variety of applications because these fabrics offer many properties. It was invented as an alternative for Silk. These applications will be the main reason you should be familiar with the concept of, “what is polyamide fabric”.

  • Tires and conveyers belts

Heavy-duty tires and conveyers belt reinforced with polyamide fabric can withstand high temperatures and fast curing cycles. The superior performance is because of its high-temperature stability, high strength, and elasticity.

Tires and Conveyers belts
Tires and Conveyers belts
  • Carpeting

The carpet industry was revolutionized when DuPont invented Bulk Continuous Filament (BCF) process to impart bulk to nylon for making carpets.

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  • Coated Fabrics

Nylon fabrics can withstand a temperature of 200OC so it is used to coat other polymeric materials.

You can further study Polyamide fabric over WIKIPEDIA.

Other applications of polyamide fibers consist of:

  • Women Stockings
  • Bulletproof vests
  • T-shirts
  • Leggings
  • Shorts
  • Stretch pants