What Is Polyethylene Terephthalate?
Polyethylene terephthalate, a type of polyester, is produced industrially. It is commonly known as PET and boasts excellent transparency, strength, toughness, heat and cold resistance, water and chemical resistance, dyeability, and electrical insulation properties. Additionally, PET does not release toxic gases when burned.
Uses of Polyethylene Terephthalate
Polyethylene terephthalate is extensively used to manufacture PET bottles, packaging containers, and base materials for magnetic tape. It is also employed in synthetic fibers for various types of clothing, including fleece.
Plastic bottles, a typical application of polyethylene terephthalate, have varied uses depending on their shape, thickness, and processing techniques. These include pressure-resistant bottles for carbonated drinks and heat-resistant bottles for hot beverages.
Principle of Polyethylene Terephthalate
Polyethylene terephthalate is synthesized by reacting dimethyl terephthalate or terephthalic acid with ethylene glycol, followed by polycondensation and distillation of glycol. Based on the processing method, it can be categorized into C-PET (crystalline polyethylene terephthalate) and A-PET (amorphous polyethylene terephthalate).
1. C-PET
C-PET, known for its high crystallinity, is produced by slowly cooling the molten polymer. It is characterized by its high strength and heat resistance, making it suitable for oven containers and retort pouch foods. C-PET’s high oxygen barrier properties also enable long-term storage in food containers.
2. A-PET
A-PET is made by rapidly cooling the melted polymer, resulting in a more flexible and impact-resistant material than C-PET. However, it is susceptible to crystallization over time or when exposed to heat. A-PET is often used for food containers where heat resistance is not a requirement, such as for salads and sashimi.
Other Information on Polyethylene Terephthalate
1. G-PET
G-PET (glycol modified polyethylene terephthalate) is a polymer variant where a portion of ethylene glycol is substituted with 1,4-cyclohexanedimethanol. This modification prevents crystallization even after prolonged use or exposure to heat. G-PET is valued for its transparency, gloss, printing properties, tensile strength, and impact resistance, making it ideal for high-performance cosmetic containers and 3D printer filaments. It also allows for the production of highly transparent and aesthetically pleasing products with thick walls.
2. GF-PET
GF-PET (glass fiber reinforced polyethylene terephthalate) combines polyethylene terephthalate and glass fiber to create an engineering plastic with high mechanical strength. In addition to inherent heat resistance, chemical resistance, and dimensional stability, GF-PET is lightweight yet strong. It is widely used in the automotive, home appliance, and electronic device industries.