Polyethylene terephthalate PET is synthesized from terephthalic acid TPA and ethylene glycol EG through a two-step process: esterification and polycondensation.1. Esterification: TPA and EG react to form bis 2-hydroxyethyl terephthalate BHET .2. Polycondensation: BHET undergoes a condensation reaction to form PET.Optimal reaction conditions for synthesizing PET:1. Esterification:- Temperature: 220-260C- Pressure: Atmospheric pressure- Catalyst: Zinc or manganese acetate, or titanium alkoxide- Molar ratio of EG to TPA: 1.1-1.5:1- Reaction time: 1-3 hours2. Polycondensation:- Temperature: 270-290C- Pressure: Reduced pressure 0.1-1 mmHg - Catalyst: Antimony trioxide or titanium alkoxide- Reaction time: 1-3 hoursThe reaction conditions can affect the properties of the resulting PET polymer:1. Temperature: Higher temperatures can increase the reaction rate, leading to a higher molecular weight and improved mechanical properties. However, excessive temperatures can cause side reactions and degradation of the polymer.2. Pressure: Reduced pressure during polycondensation helps remove the byproduct water or ethylene glycol and promotes the formation of high molecular weight PET. 3. Catalyst: The choice of catalyst can influence the reaction rate, molecular weight, and color of the PET. Antimony trioxide is commonly used due to its high catalytic activity and low cost, but it can cause a yellowish color in the polymer. Titanium alkoxide catalysts can produce a clearer PET but may have lower catalytic activity.4. Molar ratio of EG to TPA: A higher molar ratio of EG to TPA can increase the reaction rate and molecular weight of PET. However, excessive amounts of EG can lead to the formation of diethylene glycol DEG units in the polymer, which can negatively impact the polymer's properties.5. Reaction time: Longer reaction times can lead to higher molecular weight PET, but excessive reaction times can cause degradation of the polymer.By controlling these reaction conditions, it is possible to tailor the properties of the resulting PET polymer for specific applications, such as packaging, textiles, or engineering plastics.