PET is polyethylene terephthalate, a thermoplastic polyester, referred to as PET or PEIT. It is made of condensation products of terephthalic acid and ethylene glycol, and is collectively referred to as thermoplastic polyester or saturated polyester together with PBT. PET has good fiber-forming properties, mechanical properties, wear resistance, creep resistance, low water absorption and electrical insulation properties. This material belongs to crystalline saturated polyester, usually milky white or light yellow, with a highly crystalline polymer structure and a smooth and glossy surface. The glass transition temperature of PET is 69℃, the softening range is 230-240℃, and the melting point is 255-260℃. 12 PET material is highly safe, green and environmentally friendly, does not produce toxic substances or gases, and meets food-grade safety standards. Therefore, it has a wide range of applications in daily life, such as mineral water bottles, cling film, plastic packaging bottles, etc. In addition, PET also has good creep resistance, fatigue resistance, abrasion resistance and dimensional stability, as well as high hardness and toughness. It has good electrical insulation properties and is less affected by temperature, but has poor corona resistance. PET is stable to organic solvents such as acetone, benzene, toluene, trichloroethane, carbon tetrachloride and oils, and has high resistance to some oxidants such as hydrogen peroxide, sodium hypochlorite and potassium dichromate. PET has excellent weather resistance and can be used outdoors for a long time.