What are the uses of PTFE

Teflon

Teflon was discovered by a stupid accident. In 1938 a chemist with a tendency to perfectionism by the name of Roy Plunkett wondered why the tetrafluoroethene bottle, which according to the label should contain exactly 1000 g of gas, only contained 990 g. A normal person would now have thought: "What the heck? Then just 10 g are missing". Not so Plunkett. He got to the bottom of the matter, opened the gas bottle and found a white powder at the bottom of the bottle which he could not dissolve with any acid or lye and which was also very heat-resistant. The Teflon was discovered. First investigations of the new material showed that it consists of chains of approx. 100,000 carbon atoms, which are each connected to two fluorine atoms.

properties

Teflon is resistant to strong acids and strong alkalis, and hardly any solvents dissolve it. Even aqua regia, which can be used to dissolve gold, does not attack Teflon. Teflon is also extremely heat-resistant, it has a melting point of 327ºC. At temperatures above 400ºC, Teflon decomposes, releasing toxic fluorine gases.

In principle, Teflon is a thermoplastic, but it cannot yet be deformed at "reasonable" temperatures; in some cases it even has more of the properties of a thermoset.

use

Probably the best-known use of Teflon is the non-stick coating of frying pans, which was invented in the 1950s. To do this, the metal surface of the frying pan is treated with hydrochloric acid; the acid etches the metal somewhat, and the metal surface becomes more porous. Now a Teflon emulsion is applied, Teflon droplets get stuck in the resulting pores of the metal. Now the frying pan is heated and the individual drops of Teflon combine to form a continuous layer.

"In PTFE-coated pans and other kitchen utensils, food can still burn, but no longer burn. Nothing sticks to the coating, not even fried eggs. It can even be fried without fat. The pans are just as easy to clean as porcelain."

(Der Spiegel 20/1966)

In 1969 the Gore-Tex fabric was invented. The Teflon was heated and then rolled into thin films. These artificial membranes contain billions of tiny pores that are large enough for water molecules but too small for water droplets. When the fabric is exposed to the rain, the skin does not get wet, but the sweat, which is excreted as water vapor, can escape through the fabric.

Teflon is also used in many other ways in everyday life, for example as a dirt-repellent layer on clothing, as dental floss, as a sealing material for water pipes and so on.

Teflon is also used in space travel, for example in space suits. However, NASA's claim is wrong that Teflon and thus the coated frying pan were only invented through space travel. Teflon was around long before space travel.

synthesis

Teflon is produced by radical polymerization of tetrafluoroethene under high pressure.

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