How sustainable is polyester?

It is common knowledge that fossil fuels have a negative impact on the environment. But did you know that many clothes are also made of petroleum? And not just a little bit. The fashion industry is heavily dependent on the oil industry. Polyester currently accounts for about 52% of the fibre production for clothing. That equates to 57 million tonnes! (Source: Textile Exchange Preferred Fiber and Materials Market Report 2021). Wondering why that’s an issue? Then keep reading…

A toxic dream for the glamorous fashion industry

The versatility of polyester fabrics

Firstly, it’s important to understand why polyester has become such a popular material. The explanation is simple: polyester is a material that’s easy to use. You can make it look like cotton, silk, wool, you name it, and it is a lot cheaper than these natural materials. That explains why many brands want to use it for their designs. Moreover, the design opportunities with polyester are greater than with natural materials. A pleated skirt, for instance, cannot be made without polyester because it’s crucial that the skirt retains its pleats and polyester will get relatively solid pleats under heat and pressure.

Functionality

Polyester is often combined with other materials to make a softer blend. The addition of strong polyester to another material can also ensure that clothes last longer and keep their shape. Their durability is therefore increased. 

Polyester is mainly blended with natural fibres such as cotton. Unfortunately, these kinds of blends make it difficult to recycle the clothes in the end-of-life phase. Also, you can get skin irritations by wearing polyester (blends), whereas many natural materials are hypoallergenic.

A major plus point is the functionality of polyester. It is easy to maintain and can last a long time. You usually don’t have to iron it because one of its properties is being wrinkle-free.

Polyester is also weather-resistant and quick-drying, so you’ll often find it in outdoor clothing, swimwear, jackets and sportswear. The fabric can also provide a lot of warmth, for example in fleeces. However, it’s not very breathable so polyester causes you to sweat faster and the fabric does not absorb moisture.

A cheap fibre if you don’t consider its true cost

And last but not least, polyester is a cheap material, especially when compared to plant and animal-based materials. This makes the choice very easy for fast-fashion brands and trend lovers. It enables them to produce more for less and to offer products at a low price. 

Besides being a cheap fabric, polyester is easily available in large quantities. Of course, the availability does depend on whether and when the fossil source is going to be depleted. But climate-wise, its availability does not depend on whether or not the harvest is successful, which is the case with cotton, for example.

A miracle fabric?

The history of polyester

Polyester is a synthetic, man-made material that was invented in the United States, entered the market around the middle of the 20^th century, and became increasingly popular. So quickly, in fact, that since the 1970s it has dominated the fashion industry. The textile fibre polyester is derived from natural petroleum, a fossil fuel.

Today, the recycled version (recycled PET) in particular is praised as a sustainable material due to its ​“low ecological footprint”. Interested in reading more about recycled polyester? Click here. Spoiler alert: plastic clothing always causes environmental pollution, even when it’s made from recycled materials.

Accelerating fast fashion

The emergence of polyester in the fashion industry allowed the process from design to sale to speed up a gear. Trends come and go from one day to the next. Also known as the phenomenon of ​“fast fashion”.

The term fast fashion mainly refers to the speed at which the conceived design is executed in factories, then proceeds to hang on shop shelves and ends up in the consumer’s wardrobe. And in order to make these fast fashion trends available to everyone ASAP, they cut back on quality. Material choices are made on a budgetary basis, making polyester particularly popular in the fast fashion world.

Due to high trend sensitivity and low prices, people end up with closets full of unworn clothes. And because the clothes are cheap, people are more likely to discard them ​“because it was only 5 euros”. As a result, more and more polyester clothing is ending up in landfill.

How is polyester made?

Fossil petroleum

Polyester is a non-renewable material because it’s derived from raw materials from depletable resources, petrochemicals. 

Polyester’s chemical name constitutes of poly, meaning ​“multiple”, and ester, an organic chemical base compound. The main ingredient of polyester is ethylene, a polymer extracted from (refined) petroleum. Subsequently, dimethyl terephthalate starts a reaction with ethylene glycol, in the presence of a catalyst at a high temperature. 

This produces a monomer of alcohol that is combined with terephthalic acid and brought to a high temperature (280°C). From this newly formed polyester, which is transparent and melted, long strands are formed. These strips then go through a cooling process to dry. Afterwards, the pieces of polyester can be melted again to spin thread, wind it and finally weave or knit it into a piece of fabric (source: Madehow).

China is the largest producer of polyester fabrics, but India, Japan, Indonesia, and Taiwan also produce and export a considerable amount of the material (source: Sewport).

The difference between PET and PCDT

There are essentially two different types of polyester: PET and PCDT. There are also plant-based polyesters, but there aren’t (yet) many clothes made from these materials available in shops. 

You probably know PET from the plastic bottles which bear the same name. The abbreviation stands for polyethylene terephthalate and it’s a thermoplastic polymer from the polyester family. Most polyester used in clothing is PET but sometimes PCDT is used because it has more elastic properties. PCDT has a different chemical structure and a different production process but consists of the same elements (source: Sewport).

The downsides of polyester

Polyester has a (negative) impact on the environment in all of its various ​“life stages”. This includes the extraction of petroleum, the production of the polyester, the use phase and the end-of-life of polyester. It’s important to include all these steps when analysing the sustainability of polyester. 

Drilling for oil

In order to make polyester, petroleum is needed, which is extracted from the earth. This can be done on land but also at sea. In itself, this process is not actually polluting, except if there is a leak under water. The same can happen during transport (by ship) when the oil has already been extracted. 

How much CO2 is emitted during production?

In order to convert the petroleum into usable polyester for clothing, an enormous amount of energy and water is required to heat and cool the material, among other things. 

However, a lot of pollution is created in generating the required energy. To run polyester factories, energy is supplied by burning oil or coal. Especially in China, the factories often operate on coal energy, which results in huge emissions. 

According to calculations, polyester production costs 125 MJ/​kg of polyester fibre (source: Muthu S) and emits 27.2 kg CO2 eq/​kg of polyester woven fabric (source: European Commission’s Joint Research Centre). According to the Ellen MacArthur Foundation report ​“A New Textiles Economy: Redesigning fashion’s future” from 2017, polyester production in 2050 could even consume more than 26% of the carbon budget that is foreseen with a 2‑degree temperature rise!

Water pollution

In addition, the poor management of wastewater in the supply chain can cause soil and water pollution. This occurs because sewage containing dyes and/​or chemicals flows straight from the factories into nearby water. 

This has devastating consequences for both the environment and the health of nearby animals and communities (source: Environmental Sciences Europe). They can no longer use the water for drinking and growing food.

Microplastics, the dark side of polyester

Microplastics are all around us nowadays! And the polyester clothes that we make, buy, wear and wash are part of the cause. Most microplastic pollution caused by polyester clothing, occurs in the user phase, mainly during laundry. Each wash releases fibres from the fabric. This happens with clothing made from any fabric, but it’s not always as harmful.

Because polyester and other synthetic fabrics such as acrylic are, roughly speaking, made from plastic fibres, these pieces end up in the environment in the form of microplastics. The pieces are so small (0.05 – 5mm) that they are difficult to filter out. According to a 2017 study by the IUCN (International Union For Conservation of Nature), 35% of microplastic pollution in oceans comes from synthetic textiles. 

According to the Marine Pollution Bulletin, one wash of 6kg of 100% polyester clothing releases 496,030 10µm of microplastics. This is comparable to one full washing drum containing 20 to 30 football shirts or shorts from a football team in total. In the case of polyester-cotton blends, this amounts to 137,951 10µm microplastics per 6kg wash.

Through the washing machine, they end up in nearby water streams such as rivers and oceans, and thus in our drinking water and food chain. Scientists from the VU Amsterdam even found microplastic particles in human blood. 

Textile landfill

Another way in which polyester clothing leads to plastic pollution is through landfill disposal. According to the EU, Europeans each consume almost 26 kg of textiles per year and throw away about 11 kg. Used clothes can be exported outside the EU, but are mostly (87%) burned or dumped in landfill.

Because polyester is ​“long-lasting” and non-biodegradable, these clothes stay in landfills for a long time or end up in surrounding land or water. There they resume their ​“infinite” life. The polyester is capable of breaking down into smaller and smaller particles (into microplastics), but unfortunately, these remain on earth forever. There are different opinions about how long it takes for polyester to completely biodegrade, but we can assume that it takes centuries (source: Sewport).

To buy or not to buy…

COSH recommends not buying polyester clothing if you don’t need to. Many garments like blouses, dresses and trousers can be made from a more sustainable alternative such as organic cotton, linen, hemp, Ecovero viscose or Tencel. For garments that don’t need to be washed often, such as winter jackets and backpacks, it’s better to choose recycled polyester. You can read more about that material in the following blog.

We at COSH do not consider polyester to be a circular material because it’s not biodegradable and in a blended form, it’s barely getting recycled at the moment. The recycled polyester you find in shops now is nearly always made from recycled PET bottles and not from recycled clothing. Unfortunately, this is not going to change any time soon as recycling is strictly regulated in the EU. Also, the quality of the material decreases each time it is mechanically recycled (source: Swiss Federal Office for the Environment).

What about the polyester clothes that are already in my closet?

Please wear the existing clothes made of this material until they are really at the end of their life cycle, and take good care of the fabric. Look into microplastic filters for your washing machine or buy a Guppyfriend laundry bag, which stops microplastics from entering water systems. This way, you can limit the pollution caused by your clothes as much as possible. In short, make sure that the clothes last as long as possible and that they only end up in the right recycling spot when there’s no other solution. This way, we can look forward to a sustainable future with all polyester clothing that’s in existence today.