Polyethylene terephthalate (PET) is the most prominent variety among thermoplastic polyesters-commonly known as polyester resin-and is a polymeric compound produced through the polycondensation of terephthalic acid (PTA) and ethylene glycol (EG). It is a condensation polymer of terephthalic acid and ethylene glycol; together with PBT, it is collectively referred to as thermoplastic polyester or saturated polyester.
PET is a highly crystalline polymer that appears milky-white or pale yellow, featuring a smooth and glossy surface. When utilized as beverage packaging bottles, it offers numerous advantages, including light weight, high mechanical strength, excellent transparency, and superior gas barrier properties. It exhibits good creep resistance, fatigue resistance, abrasion resistance, and dimensional stability; furthermore, it demonstrates low wear and high hardness. While possessing relatively high toughness compared to other thermoplastics, its hardness is considered relatively low in the context of packaging materials, making it susceptible to cracking under strong pressure. It demonstrates excellent electrical insulation properties with minimal sensitivity to temperature fluctuations, though its resistance to corona discharge is relatively poor. However, its heat resistance is limited; when used as a packaging bottle, the operating temperature typically should not exceed 65°C, as exposure to high-temperature liquids can lead to deformation and potentially result in the leaching of harmful substances. It is non-toxic, weather-resistant, and chemically stable; additionally, it features low water absorption and exhibits resistance to weak acids and organic solvents.