INTRODUCTION Figure 1: Molecular Structure of PET PET (or PETE) is also known as polyethylene terephthalate or (C10H8O4)n. Its natural state is a colorless, semi-crystalline resin when combined with other materials like glass fiber or carbon nanotubes, it increases the material’s strength. Polyethylene terephthalate melts at 260°C and Amorphous density (at 25oC) is 1.33 g/cm3. PET can be produced by 2 different reactions as a product of polymerization. The first reaction is between ethylene glycol with terephthalic acid. The second one is the reaction of ethylene glycol with dimethyl terephthalate in acid catalyst. Figure 2: Molecular Structure of ethylene glycol Ethylene glycol is an organic compound with the formula (CH2OH)2. It is …show more content…
It is used as a commodity chemical, principally as a starting compound for polyester manufacturing. Figure 4: Molecular Structure of dimethyl terephthalate Dimethyl terephthalate is the organic compound with formula C10H10O4. It is the diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colorless liquid. BACKGROUND ON THE PRODUCT Figure 5: PET …show more content…
Therefore, water and ethylene terephthalate are formed. 2. Mechanism between dimethyl terephthalic and ethylene glycol In this reaction, heat use as catalyst. Figure 10: Mechanism between dimethyl terephthalate and ethylene glycol As we known heat is involved in this reaction. Figure 10 shows the reaction between dimethyl terephthalate and ethylene glycol. In this reaction, oxygen acts as a nucleophile and hydrogen act as an electrophile. Therefore, hydrogen pull electron from oxygen to form methanol and ethylene terephthalate is formed. INDUSTRIAL SCALE PREPARTION Polyethylene Terephthalate is produced from high purity Ethylene glycol (EG) and Terephthalic acid (TPA) or Dimethyl Terephthalate (DMT). Both processes first produce the intermediate bis-(2-hydroxyethyl)-terephthalate (BHET) monomer and either methanol in DMT process or water in TPA process. The BHET monomer is then polymerized under reduced pressure with heat and catalyst to produce PET resins. The primary reaction for the DMT process is: Figure 11: Primary reaction of DMT process The primary reaction for the TPA process