When we speak of the synthetic fibre polyester, we are referring to all textiles and fabrics that are made from polyester yarn. This can be fleece or neoprene, for example. Or also many textiles with a high stretch content, such as running tights or swimwear, and also, for example, softshell jackets as well as all kinds of athleisure wear. Most synthetic fibres are made of polyethylene terephthalate - PET for short - or polycarbonate, but numerous other plastics also provide the basis for polyester.
Polyester fibres are three times finer than silk and can be woven very tightly into super small-pored fabrics that are wind and waterproof. The fabric remains breathable and is also very light, heat-resistant and crease-resistant. This is particularly interesting for technical textiles, for example in the outdoor sector: from waterproof hiking clothing to textile travel equipment that needs to be stowed away compactly and easily, to backpacks, insulated or hammocks and, last but not least, the tent.
Another great advantage of synthetic fibres is that they can be easily modified. Thus, polyester fabric is often enriched with UV protection or additionally impregnated to make it even more weather resistant.
The uncomplicated fibre can be combined with other textile fibres and is therefore often found in blended fabrics, for example with cotton or viscose. The polyester content provides the fabric with a higher dimensional stability and ensures that the garment is easier to care for, crease-resistant or stretchy.
Compared to natural fibres, sports and outdoor clothing made of polyester develops unpleasant odours more quickly. This is because the smooth fibres hardly absorb any moisture, but only absorb it: Sweat is automatically wicked to the outside. This ensures a pleasant feeling when worn for a while, because no moisture builds up and the textile never feels damp. The skin, however, does, at least in the case of heavy perspiration. Polyester fibres lack the natural protective film that ensures that absorbent natural fibres such as wool or cotton do not give off an unpleasant smell of perspiration for a very long time. Thanks to this, natural fibres have the ability to clean themselves almost automatically. Polyester cannot do this and therefore has to be washed much more often.
That in itself is a big problem: in the washing machine, microplastic dissolves from the polyester fabric and ends up in the environment via wastewater. The synthetic fiber is so robust that it can hardly be degraded. And there are also downsides to the production process. Although less water is needed than in the production of cotton, the energy input is much higher. Polyester is made from crude oil and is not only found in textiles, but also in PET bottles, plastic-containing products and packaging. 100 million barrels of crude oil are used for it every year. The textile industry accounts for 70 percent.
In order to conserve resources, many textile manufacturers use recycled polyester. Patagonia is also a pioneer here and has been processing fabrics from recycled PET bottles, plastic waste from the oceans and worn-out garments for years. There are also many sustainable sneaker labelsthat make running shoes from recycled polyester. No new petroleum needs to be used for the recycled fibers and they are not inferior to "new" fibers. However, it's important to remember that this doesn't solve the microplastic problem, and the recycling process also requires a lot of energy. In addition, recycling plastic has limits; PET cannot be endlessly reused. And it is currently hardly possible to recycle polyester from blended fabrics.