Polyethylene terephthalate (PET), chemical formula (C10H8O4) N, is by dimethyl terephthalate and ethylene glycol ester exchange or to terephthalate and ethylene glycol esterification synthesis of dihydroxyethyl terephthalate, and then the condensation reaction. Is a crystalline saturated polyester, milky white or light yellow, highly crystalline polymer, smooth and shiny surface, is a common resin in life, can be divided into APET, RPET and PETG.In a wide temperature range with excellent physical and mechanical properties, long-term use temperature up to 120C, excellent electrical insulation, even at high temperature and high frequency, its electrical properties are still good, but the corona resistance is poor, creep resistance, fatigue resistance, friction resistance, dimensional stability is very good.