Polyethylene terephthalate is the most important type of thermoplastic polyester. The English name is polyethylene terephthalate (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 high crystalline polymer with a smooth surface, resistance to creep, fatigue, friction and dimensional stability, low wear and high hardness, and the highest toughness in thermoplastics. Electrical insulation performance is less affected by temperature, but poor corona resistance, non-toxic, weather resistant, chemical resistant, good water absorption, weak acid and organic solvents.