PETG, also known as Polyethylene terephthalate glycol (PETG) (according to the international designation PET-G, we usually call it PETG, sometimes for some reason coPET) is a modification of polyethylene terephthalate (PET or PET), which overcomes its certain disadvantages.

The disadvantage of PET is that it becomes opaque when cooled slowly due to partial crystallization. For thin parts, this is prevented by rapid cooling (for example, in PET bottles, which must remain transparent). If it is necessary to remove heat from large or thick-walled products, then transparency cannot be ensured. Replacing part of the ethylene glycol (1,2-ethanediol) with dimethanol cyclohexane as the diol in the production of this ester results in significant steric interference (due to the configuration of the cyclohexane). The plastic is called PETG because the modified glycol has a much lower melting point and remains clear in all operations, a clear advantage when thermoforming PETG film/sheet parts.

Currently, PETG (PETG) is common as an engineering plastic for printing on 3D printers, surpassing PLA in heat shrink.

General characteristics and properties:

Transparent amorphous material. The glass transition temperature is about 80 - 85 °C.
It has high rigidity and hardness.
Resistant to dilute acids and alkalis, salt solutions, soaps, oils, alcohols, aliphatic hydrocarbons.
Well sterilized.