Synthesis and Mathematical Modelling of Polyethylene Terephthalate via Direct Esterification in a Laboratory Scale Unit

Synthesis of polyethylene terephthalate (PET) in laboratory is a challenging task due to high reaction temperature up to 280ºC and high pressure in esterification step and low vacuum in polycondensation step. In this research, synthesis of PET, in a laboratory size unit was studied via direct esterification of terephthalic acid and ethylene glycol. Antimony oxide was added as catalyst for polycondensation. Mathematical model of process is presented based on the mass balance of different species such as acid and hydroxyl end groups, water output, diester groups during both esterification and polycondensation steps. Derived governing equations were integrated numerically using Runge-Kutta method. Reacting mixture mass variation was included in the model. Comparison of experimental and simulation results shows promising and good agreement. Hence, the model could be used as a powerful tool for engineering process. The model was applied to study different aspects of polymerization process.