What is polyethylene terephthalate (PET)?

PET is a polymer synthesized from terephthalic acid and ethylene glycol and thus forms a thermoplastic polyester. Depending on the manufacturing process, it can be amorphous (transparent) or semi-crystalline with a crystallinity of 30 – 40 %. The crystallization rate during production is very low. PET is characterized in particular by its very good sliding properties and has the best dimensional stability. PET also has high hardness, rigidity, strength and abrasion resistance, even at low temperatures down to – 40 °C. The upper operating temperature is 110 °C, with glass fiber reinforcement even up to 255 °C, together with extremely low thermal expansion. PET is resistant to hydrocarbons, oils, greases, fuels, aliphatic esters, weak acids and bases, and therefore has good chemical resistance. It is not resistant to hot water and water vapor, acetone, halogenated hydrocarbons and strong acids and bases. PET is best known in the form of PET bottles, as PET has a favorable permeation behavior towards carbon dioxide. PET is also used in mechanical engineering as gear wheels, rollers and ball bearings and in electrical engineering.