What’s the difference between PET and PETG plastics? While the acronyms look almost identical with only one letter differentiating the two, their separate chemical properties and laboratory uses truly set these two plastics apart. PET, or ‘polyethylene terephthalate’, is a combination of two monomers. PETG is of the same chemical composition as PET but with the addition of glycol. With just this one addition, the chemical composition is completely changed, creating a whole new plastic.
The addition of glycol to create PETG removes the hazing effect seen during heating and also prevents an undesirable crystallization effect that causes standard PET to become brittle. Additionally, the inclusion of glycol in this plastic will transform the outer walls of a bottle into a softer and more pliable material, making it easier and more comfortable to grip. Despite these advantages, this softer outer wall is easier to scratch, more susceptible to damaging UV light, and cannot be autoclaved. All things considered, these drawbacks are relatively minor when compared to PETG’s superior heat handling, shock resistance, and comfortable grip.