The optimum reaction conditions for the synthesis of polyethylene terephthalate PET using terephthalic acid and ethylene glycol as starting materials are as follows:1. Temperature: The reaction typically occurs in two stages. In the first stage, esterification takes place at temperatures between 220-260C. In the second stage, polycondensation occurs at temperatures between 270-290C under vacuum.2. Pressure: The first stage of the reaction esterification is carried out at atmospheric pressure. In the second stage polycondensation , the pressure is reduced to a vacuum around 0.1-1.0 mbar to facilitate the removal of byproducts and to drive the reaction to completion.3. Catalyst: Common catalysts used for the synthesis of PET include antimony trioxide Sb2O3 , titanium-based catalysts e.g., titanium isopropoxide , and germanium-based catalysts e.g., germanium dioxide . Antimony trioxide is the most widely used catalyst, typically added in concentrations of 100-300 ppm.It is important to note that the specific conditions may vary depending on the desired properties of the final PET product and the specific process used for synthesis.