Whether it’s a fleece jacket, sportswear or disposable water bottle, they all contain polyester. What is that exactly? "Poly", Greek, means many. Polyesters are therefore multiple esters. The group of esters includes substances that are different, but always built according to the same principle. The term polyester covers a broad group of plastics. Everyone knows one polyester - poly(ethylene) terephthalate, better known as PET.
recycle polyester
The PET is the plastic Beverage bottles , which are loyal companions for most of us. Thanks to PET, they are light and relatively dense, so that the gas from the carbonic acid does not escape and evaporate. PET bottles can also be recycled. To do this, the bottles are shredded, the product is cleaned, melted and converted back into PET granulate. However, the sorted collection of PET bottles is a challenge. Around 94% of PET was recycled in Germany in 2013. A third of new products are new PET bottles, and the textile fiber industry uses around 29% of the recycled granules.
Polyester fibers absorb less water
Thin PET fibers are suitable, for example, for sportswear and functional clothing. The fabric made from polyester fibers absorbs less water than those made from cotton. The industry uses slightly thicker fibers for zippers. 27% of the processed PET goes into the manufacture of tear-resistant films such as food packaging or rescue blankets. The industry produces these by processing molten PET on rollers and stretching it. This creates a product that is tear-resistant. In addition, this can be coated with aluminum, for example. Rescue foils produced in this way are very thin at around 15 micrometers - only 67 layers make up one millimeter.
Polyester also in nature
In addition to PET, there are other polyesters. This also occurs in nature: ground bees produce polyester and use it to line their nests. Unsaturated polyester resins are found, for example, in components for automobiles and pleasure boats. Here the polyester is usually reinforced with fibers such as glass. An example of synthetic but biodegradable polyesters are the polylactides. They are often mixed with other raw bioplastics (“PLA blends”), which we find in films or cosmetics packaging, for example.