What is the Future for Polyester?
The world’s most popular fabric material drives up climate emissions and spreads plastic pollution. But what could replace it? Or are we too far gone to quit?
It’s summertime, so time to replace the jumpers and scarfs with some new shorts and t-shirts. Or new athletic wear to reach your gym goals (even if you don’t ever end up going). Perhaps an in-fashion bathing suit or two to take on vacation. For many of us, this is a formula we rinse and repeat ever year — or every season. But when removing the clothing tags, you may notice that every item is composed of the same material, even the tag itself: polyester. And this is a problem. Because it’s manufacture from oil drives up climate emissions, while its use is spreading a plastic pollution pandemic. So how did we become addicted to this material? And are we too far gone to quit it now?
Polyester is the most commonly used synthetic material in manufacturing to make furniture, pillows, bottles, and clothing (when blended with other natural fibres like cotton). It’s highly favoured due to its strength and durability, in addition to its waterproof nature and resistance to shrinkage, making it an ideal material for leisure clothing. So popular, in fact, polyester and other synthetic fibres make up 70% of clothing made.
The most popular type of polyester is polyethylene terephthalate (PET), which is derived from petroleum. Through cracking, long-chain hydrocarbons in petroleum break down into smaller, more useful chains under optimal conditions like high temperature and pressure. Ethylene is produced, which is oxidised and then hydrated to produce ethylene glycol, one of the monomers in PET. Ethylene glycol combines with terephthalic acid in polymerisation to produce PET pellets after drying. The final step is spinning; the resulting chips are melted again to create a honey-like substance, extruded through a spinneret to produce fibres.
The downside to PET
Given that it’s so durable, you’ be forgiven for wondering ‘what’s the downside?’ As stated, polyester is the most commonly used synthetic fibre, accounting for 80% of synthetic fibres produced in 2017. It is ever-present in our daily lives — to the point that a world without the material would be unimaginable to us. We unconsciously use and dispose of the material like an afterthought, and who can blame us? Living in the ‘developed world’ means the consequences are not directly in our faces. Out of sight, out of mind.
However, the production of polyester requires high energy. In fact, 14.2kg of CO2 is emitted for every one kilogram of PET produced. Approximately 342 million barrels of oil are used each year to keep up with our demand, making the process of producing PET unrenewable.
Furthermore, in the factories producing PET, the workers are underpaid, face harsh conditions ,and live in communities affected by the pollution created. Water is also deprived of water-scarce communities as it takes 100–150 litres to produce a kg of fibres. After stealing the water, the factories dump the wastewater containing toxic chemicals into the waterways as a token of gratitude. When washing textiles made of synthetic fibres like PET, the European Environment Agency cited that half a million tonnes of microfibres are shed yearly and eventually enter the oceans. In China, the source of 65% of clothing produced, the World Bank states that textile dyeing caused around 20% of industrial water pollution. As a result, diseases caused by polluted water accounted for over a hundred thousand deaths yearly. Lastly, PET is nonbiodegradable, so after use, it will remain in a landfill for centuries, and PET blended with other natural fibres cannot be recycled.
Basically, we need to move away from PET plastics — but how do we replace the otherwise reliable form of polyester?
Plant based polyester (Bio-PET)
For starters, bioplastics have been hailed as the solution to our plastic problem recently, and PET is no exception. Ethylene glycol can also be obtained from molasses ( the thick brown syrup separated from raw sugar in sugar manufacture) left over by sugar canes. The ethylene glycol combines with terephthalic acid, like regular PET, which reduces carbon emissions by 13%. However, since there is no way yet to derive terephthalic acid from nonfossil fuel sources, the monomer is still acquired from petroleum. As a result, 70% of the polyester is derived from petroleum, and the remaining 30% from molasses. Thus, there is still more work for bio-PET to be the future face of polyester.
Polylactic acids (PA)
This polyester is produced from sugar cane and carbohydrates from agricultural waste. The carbohydrate source undergoes bacterial fermentation, which produces lactic acid. This lactic acid is separated, purified, and filtered before producing PLA in a process called ring-opening polymerisation. This method does not require any fossil fuels and is completely biodegradable. PLA, after use, needs to be taken to a composting facility where the material is heated under 140 degrees so it can fully decompose. This method is preferable to sending plastics to landfills, where they will remain forever. Furthermore, Washing PLA does not lead to the shedding of microplastics. PLA is currently used in 3D printing, medical implants, disposable packing material, feminine hygiene products, and nappies.
On the other hand, PLA has a low boiling point and, therefore, not suitable to be used in more applications. Critics may also point out that the use of fertilisers to grow crops is not sustainable. Fertilisers, when run into the rivers, affect aquatic life due to the formation of algae bloom blocking sunlight.
Polyhydroxyalkanoate (PHA)
Unlike bio-PET and PLA, PHA is derived from bacteria. The bacteria culture is placed under stressful conditions, in this case, nutrient deficient and high carbon conditions, causing the bacteria to release PHA. This is because PHA accumulation enhances the stress resistance of the bacteria. Thanks to PHA’s biodegradable and compostable properties, PHA is currently used in disposable items, flower pots, fishing equipment, and medical equipment. The production of PHA does not require land or fertilisers and is less energy intensive than PET, meaning less carbon emissions.
On the flip side, PHA is made in laboratories on a small scale, not in big industries, so it is not readily available. Additionally, PHA plastics are weaker and more expensive than synthetics making them harder to implement at a large scale.
Recycled PET
Although PET is responsible for most of the waste in the oceans, it is recyclable. PET has a low melting point, so it is easily melted and moulded into a new product. The production of recycled PET products emits 90% fewer CO2 emissions in opposition to virgin PET, and the process of recycling PET emits fewer CO2 emissions than recycled glass and aluminium. However, Business Waste reports that only 60% of PET is recycled in the UK despite PET being 100% recyclable. Recycled PET is used to make fabrics that can be used in clothing, carpets, seat belts, bags, and plastic bottles. The latter is important as beverages and plastic bottles occupy a significant portion of plastic waste at 7.27% and 15.5%, respectively.
The amount of times PET can be recycled depends on the product; plastic bottles can be recycled multiple times, and a non-food container potentially 2 or 3 times, but clothing is impossible to recycle. Whether clothing made from recycled plastic is sustainable is passionately debated: even though repurposing plastic bottles into garments reduces plastic waste from bottles, recycled PET clothing still sheds microplastics in the wash and will end up in landfills when discarded.
The future
PET is popular in manufacturing for a reason: it is a durable and strong material that can withstand harsh conditions. However, virgin PET has no place in the future. So far, single-use plastic is banned in multiple countries, including the UK and EU countries, while the use of plastic bags is restricted. This shows that law enforcement phasing out plastic is internationally possible. The NRDC points out that laws against plastic also forces companies to redesign their products to make them more sustainable and influence consumers to be more conscious of the effects of plastic waste. Thus, taxing companies for PET usage might incentivise corporations to use more sustainable materials.
I have not seen many plastic straws in years; paper cutlery seems to have replaced the plastic version, while reusable water bottles are now in vogue. It is clear that change is possible, but time is ticking. How long can we continue in business as usual standards? Perhaps as long as fast-fashion exists, we won’t be able to kick the habit. Afterall, with vacation season around the corner, the shops will be stocking up with their latest lines — it’s up to us whether we feel we ‘must have’ that latest ‘must have’ — or whether, in fact, last year’s (or last decade’s) in the drawer still fits just fine.
