Sew Interesting – Polyester

Light, stretchy and wrinkle-free – we’re breaking down the origins of polyester.

Polyester is a low-cost, synthetic fibre derived from non-renewable resources such as natural gas, coal, or crude oil petroleum. Unlike animal or plant-based materials like cotton, silk and wool, polyester was invented fairly recently in England during the 1940s. It quickly rose to popularity as the clothing industry shifted towards faster and cheaper methods of textile production.

Today, polyester is the most commonly used fibre and accounts for approximately 52% of the global fibre market with China as its biggest exporter. However, this seemingly inexpensive material comes at a steep cost to our planet and community with a number of risks associated with its production and use.

Polyester is actually an umbrella term for a category of polymers. The type of polyester fibre that’s most often found in our clothing, plastic containers and water bottles is polyethylene polyester (PET). PET is formed by mixing petroleum-derived ethylene glycol and terephthalic acid to form a stable fibrous compound.

The first step of making polyester is heating ethylene glycol with dimethyl terephthalate twice to chemically create a polymer. Once combined, the liquid PET is then extruded, cooled, dried and chopped into smaller pieces. These pieces are melted once again to produce a thick, honey-like substance that is spun through a spinneret to create polyester yarn and then woven into textiles.

While polyester does not require as much land or water to produce as natural fibres, it requires more than double the amount of energy. This is because polyester is essentially produced through the extracting and burning of fossil fuels which releases methane, a fast-acting greenhouse gas that traps heat in the atmosphere and causes global warming. A single polyester t-shirt produces the equivalent of 5.5kg of carbon dioxide – enough to make you a cup of tea for a year!

What’s worse, polyester is not biodegradable which means that it takes anywhere between 20 to 200 years for a single polyester garment to decompose. That means most of the polyester garments that have ever been made are still on our planet. To make matters worse, with every wash, polyester garments release tiny fibres called microfibres into local waterways, which can flow through sewage treatment plants undetected. These plastic microfibers then bond with other harmful molecules found in wastewater and are eaten by plankton and other small sea creatures, ending up in the food chain, which in turn have been found in the placenta of unborn human babies.

The use of polyester in the clothing industry is very much tied to the rise of fast fashion: cheap clothing made from cheap fibres that are produced quickly at a large scale. Polyester manufacturing also causes a multitude of problems to workers’ health. Not only are these workers exposed to harmful toxins and carcinogens produced by the polyester making process, but poor precautions and safety conditions often cause hearing loss, skin damage and even cancer.

There’s no doubt that polyester is one of the most versatile, durable and affordable fibres out there. If you’re looking for more sustainable solutions with these properties, we recommend alternatives such as recycled polyester (rPET) or bio-based synthetics.

Recycled polyester is obtained from melting down post-consumer PET water bottles and spinning it into yarn. The pros are that it requires 59% less energy to produce compared to virgin polyester and keeps plastic materials from going to landfills. However rPET also releases microfibres when washed and the majority of its fabrics are made from plastic bottles, not used polyester clothing, adding to garment waste rather than closing the loop. There are also debates that its carbon footprint might not differ much from that of virgin polyester once we take the fibre’s first life emissions into account.

On the other hand, bio-based polyester is a ground-breaking innovation that could help us phase out fossil fuels in the future. Unlike regular PET which is made with the ethylene glycol from petroleum, plant-based polyesters use ethylene from natural sources such as cane sugar.

One such solution known as bio-based butanediol (BDO) is being developed by Genomatica through genetically engineered E. coli that metabolises sugar. Producing polyester fibres made from plant-based materials could significantly reduce the carbon footprint of our garments. Geno’s BDO material can be used for a diverse range of everyday materials and consumer products, from spandex to shoes to plastics in cars and electronics. As biotechnology becomes more accessible and readily available to mainstream markets, we expect to see more clothing brands adopt their innovations, moving one step closer towards a regenerative industry.

The Guardian
Textile Exchange –  Preferred Fiber and Materials Market Report 2021 (page 4)
Biomedical Journal of Scientific Research: A Study on the Solutions of Environment Pollutions and Workers Health Problems Caused by Textile Manufacturing Operations
Fashion United