Kinetic Studies of Polyethylene Terephthalate Synthesis with Titanium-Based Catalyst

Summary: Thermogravimetric analysis and stirred tank reactor techiques were used to study the kinetic of polycondensation of bis-hydroxy ethylene terephthalate catalyzed by titanium tetrabutylate. Polycondensation reaction can be modelled best with a second order reaction with respect to hydroxyl end groups concentration. Titanium tetrabutylate is a precursor and needs preactivation for polycondensation catalysis. Kinetic data depends on the mode of operation in thermogravimetric analysis. In nonisothermal mode, the overall activation energy was determined by model-free method and the pre-exponential factor was found to be affected by catalyst concentration. The kinetic study of isothermal reaction in thermogravimetric analysis is complex due to lack of a precise way to reach desired isothermal temperature and high activity of the catalyst. Titanium catalyst shows higher activity and lower selectivity than antimony catalyst but its activity is affected by the nature of ligands.