Most polyester fabric is not biodegradable.
Polyester, or polyethylene terephthalate, is made from a chemical reaction involving crude oil, air and water. The idea of synthetic polymers was first conceived in 1926 at the labs of E.I. du Pont de Nemours and Co. in the United States, but the early research stalled. That work by W.H. Carothers, which involved mixing ethylene glycol and terephthalic acid, was later picked up by British scientists John Whinfield and James Dickson, who patented polyethylene terephthalate (PET) or PETE in 1941, according to What is Polyester.
It's not considered biodegradable because most polyester takes from 20 to 40 years to break down, depending on the environment it's in.
How is polyester made?
To understand why it lasts so long, it helps to know how it's made. Polyester is made at very high temperatures in a vacuum. Carboxyl acid and alcohol from petroleum are mixed to form a compound known as an ester, which is heated up and stretched into long fibers, according to Plastic Insight. This is chopped into chips or pellets, which are really strong.
To make polyester fiber, the pellets are forced through small holes or spinnerets. When they come through the other side, the fibers solidify, creating a continuous line that resembles fishing line. That line can then be made into just about anything.
Can you recycle polyester?
Yes, you can recycle polyester. In fact, use of recycled plastic in the fashion industry has been increasing, reports FashionUnited, thanks to the efforts of groups like the nonprofit Textile Exchange, which challenged textile and apparel companies to increase their use of recycled plastic. The challenge worked.
The nonprofit forecasts that 20% of all polyester will be recycled by 2030.
The process of making fabric from recycled polyester or other plastic is similar — it's heated up and respun into new fiber. Patagonia was the first to make fleece in this manner in 1993, and the concept has since flourished.
"Using recycled polyester lessens our dependence on petroleum as a source of raw materials," explains the Patagonia website. "It utilizes waste and reduces greenhouse gas emissions from manufacturing. It also helps to promote new recycling streams for polyester clothing that is no longer wearable."
The practice does keep more plastic out of the landfill, but plastic and polyester is not infinitely recyclable. Though it does reduce the use of "virgin" or new polyester fabric, even a recycled plastic fleece jacket will create microfibers or microplastics in your washing machine, and those microfibers end up in our waterways, a problem the Story of Stuff video above explains in detail.
Sustainable fabrics to try instead
One of the most effective but overlooked ways to lessen the impact of your clothes is to choose natural fabrics like silk, organic cotton, linen and wool.
These fabric choices lose fibers when you wash them, but those fibers biodegrade much more quickly than polyester.