PET and PETG are two types of plastic materials used to make media bottles and other laboratory containers. The main differences between PET and PETG are:
- Chemical composition – PET, or polyethylene terephthalate, is a polyester plastic. PETG, or polyethylene terephthalate glycol-modified, is a chemically modified form of PET with additional glycol groups. The glycol groups make PETG more flexible and impact-resistant than PET.
- Clarity – PETG is an amorphous plastic and provides very high clarity, while PET is semi-crystalline and slightly hazy. So PETG bottles are often preferred when optical clarity is important.
- Gas barrier – PETG has better oxygen and carbon dioxide barrier properties than PET. So PETG bottles are better for storing oxygen-sensitive media and reagents, or for culturing CO2-dependent cells.
- Chemical resistance – PETG has superior chemical resistance to solvents like acetone and chloroform compared to PET. So PETG bottles can withstand a wider range of chemicals. However, neither material has high resistance to aromatic hydrocarbons like toluene.
- Heat tolerance – The crystalline structure of PET gives it better heat tolerance than the amorphous PETG. So PET containers can usually withstand higher autoclaving temperatures. PETG starts to soften around 80°C while PET can withstand up to 125°C.
- Impact strength – PETG is tougher and more shatter-resistant than PET due to its rubber-like qualities. PETG bottles are less likely to crack or break when dropped. This makes PETG preferable for bulk media bottles that are handled frequently.
- Cost – PET is typically slightly lower in cost to produce and purchase compared to PETG due to differences in raw materials and processing. But for laboratory use, the cost difference is usually minor relative to the overall cost of media and reagents.
