Polyester fabric, the ever-so-popular smooth, strong and durable man-made synthetic fabric, is made from petroleum-based synthetic fibers. These fibers are composed of synthesized polymers, which are long chains of repeating molecules. The process of making polyester fabric is fascinating – some basic materials dug from the soil is made into a fabric of significant utility and versatility.
Polyester fabric process makes a fabric that is superior in many ways – it is made to withstand frequent use, resist wear and tear, and one that repels moisture and dries quickly. It is also made to be easily maintainable and also retain its color even with frequent washes. Polyester can also be blended with other textile fibers, even natural fibers, to make far more superior fabrics.
In this article I will cover:
- What is polyester made of?
- The manufacturing process of polyester goes through different steps as given below
- Step 1. Extraction of Crude Oil
- Step 2. Refining Crude Oil
- Step 3. Production of Ethylene and Terephthalic Acid
- Step 4. Combination of Ethylene and Terephthalic Acid
- Step 5. Polymerization of PET
- Step 6. Spinning
- Step 7. Drawing
- Making of polyester yarns
- Step 8. Winding
- Step 9. Weaving or knitting
- Making blends
- Step 10. Fabric finishes on polyester
- Environmental and sustainability concerns of how polyester is made.
- Polyester is made from Petrochemicas
- Polyester production is an Energy-Intensive Process
- Environmental pollution during and after manufacturing
What is polyester made of?
Polyester is made from petroleum-based synthetic fibers composed of synthesized polymers, known as polyethylene terephthalate (PET). So, Polyester is basically plastic in a fabric-form.
Polyester is derived from the words ‘Poly’ meaning many and Ester is the basic organic compound of polyester. Ethylene, a derivative of petroleum, is used in the manufacture of polyester.
The manufacturing process of polyester goes through different steps as given below
Step 1. Extraction of Crude Oil
The process of making polyester fabric begins with the extraction of crude oil from underground reserves.
Step 2. Refining Crude Oil
Crude oil is refined to make various petrochemicals like ethylene and terephthalic acid, that are essential components for polyester production.
Step 3. Production of Ethylene and Terephthalic Acid
Ethylene and terephthalic acid are obtained through the refining process and serve as the primary raw materials for PET production.
Step 4. Combination of Ethylene and Terephthalic Acid
Ethylene and terephthalic acid are chemically combined through a reaction to create PET (polyethylene terephthalate) as a polymer.
Step 5. Polymerization of PET
Polymerization is the process by which polyester is manufactured from the main ingredient of ethylene.
The PET polymerization process involves reacting the combined ethylene and terephthalic acid to form long-chain polymer molecules of polyethylene terephthalate.
An ester called dimethyl terephthalate is reacted with alcohol called ethylene glycol in the presence of a catalyst at a high temperature. The resulting monomer alcohol is combined with terephthalic acid at high temperatures. The polymerized material is extruded in the form of a long ribbon which is air-cooled. Once the ribbon hardens, it is cut into pellets.
Step 6. Spinning
The pellets of polyester are thermoplastic which means they can be heated and remolded into different forms.
The pellets are put into a reservoir and heated and melted to form a syrup-like solution. This solution is put into a container with small holes called spinnerets.
The solution is extruded through spinnerets and cooled by air to produce continuous filaments or fibers.
The size and shape of the spinnerets decide the diameter and shape of the fibers.
Step 7. Drawing
Fibers coming out of the spinnerets are soft. They are heat stretched up to five times their original length. This process decreases their width and increases the strength, tenacity, and resilience of the fiber. It will no longer be brittle.
Making of polyester yarns
There are two types of polyester yarns made from polyester fiber. They are called filament yarn and spun yarn.
Filament yarns can be made by grouping the long polyester filaments and twisting them together to make one long monofilament yarn that is thick and strong.
Spun yarns on the other hand are created by twisting the fibers like the way we spun cotton or wool. The long polyester fibers are cut into short pieces called staples and combined. And they are spun together to make up a yarn.
Step 8. Winding
The fibers are then wound onto cones or large bobbins ready to weave or crimped and cut into staple lengths to blend with other fibers.
Step 9. Weaving or knitting
The yarn bobbins or cones are loaded onto looms or knitting machines, depending on the desired fabric type.
In weaving, the polyester yarns are interlaced at right angles to create a woven fabric. The yarns running lengthwise are called the warp, while the yarns running widthwise are known as the weft. This weaving process creates various fabric patterns, such as plain, twill, or satin weaves, depending on the arrangement of the yarns.
In knitting, the polyester yarns are formed into fabric through a series of interconnected loops. This process is commonly used for creating knitwear, jerseys, and stretchy fabrics.
Polyester can be combined with other fibers to make a variety of blends. The most popular blend might be that of cotton and polyester. Cotton makes the fabric more absorbing and comfortable whereas polyester makes it more stain and wrinkle-free.
Polyester is also blended with wool to make it more wrinkle-free and increase the durability of the fabric.
Polyester and rayon are other popular blends where the combination gives it a different texture, makes it more absorbent, and a good drape.
Similarly, polyester and nylon blend produces strong, durable, easy to launder, and resistant to mildew. But since both these fibers do not have absorbency, the fabric made of these blends is not ideal for warm and humid climates.
As a fabric with multiple uses in manufacturing, dressmaking, and home decor the reputation of polyester is stellar. But the production leaves a lot to be desired, as it is derived from petrochemicals, and its production involves energy-intensive processes.
Step 10. Fabric finishes on polyester
Fabric finishes are applied after the polyester fabric is made is to enhance its performance. Some common finishes applied are anti-static finish, anti-pill finish, flame retardant finish, water repellent finish, moisture wicking finish, and UV resistant finish.
Environmental and sustainability concerns of how polyester is made.
Polyester is made from Petrochemicas
Polyester is made from non-renewable resources, derived from crude oil or natural gas. It is also not bio-degradable. ie it doesnot decompose over time, remaining in the environment for extended periods.
Polyester production is an Energy-Intensive Process
The transformation of petrochemicals into polyester fibers involves energy-intensive processes, including high-temperature reactions and chemical inputs.
Environmental pollution during and after manufacturing
Polyester sheds microfibers or plastic particles during washing. These particles can find their way into waterways and marine ecosystems, potentially harming aquatic life.
Efforts are on reduce its problems like plastic pollution due to shedding during washing and its limited biodegradability. And if these production practices are successful, it will truly add to the charm of the fabric, that is already one of the most popular one.
Read more about the production process of polyester :
Books : Textile fibers, dyes, finishes, and processes : A concise guide (Howard L. Needles).
Book : Monomers, Polymers and Composites from Renewable Resources by Mohamed Naceur Belgacem, Alessandro Gandini – This book describes how “dwindling of fossil resources, coupled with the drastic increase in oil prices” have led to the production and popularity of polyester fabric.