Polyethylene terephthalate is the most important type of thermoplastic polyester, English name Polythylene terephthalate referred to as PET or PETP (hereinafter referred to as PET), commonly known as polyester resin. It is a polycondensate of terephthalic acid and ethylene glycol, together with PBT, collectively referred to as thermoplastic polyester, or saturated polyester. PET is a milky white or light yellow highly crystalline polymer with a smooth and shiny surface. Creep resistance, fatigue resistance, friction resistance and dimensional stability, abrasion resistance is small, hardness is high, and it has the highest toughness among thermoplastics; good electrical insulation performance, low temperature influence, but poor corona resistance. Non-toxic, weather-resistant, chemical resistant, stable, low water absorption, resistant to weak acids and organic solvents.