Kinetics of poly(ethylene terephthalate) fiber glycolysis in ethylene glycol

The glycolysis of poly(ethylene terephthalate) (PET) fiber is carried out using excess ethylene glycol (EG) in the presence of Zn/Al mixed oxides. The effects of the weight ratio of EG to PET, the weight ratio of catalyst to PET, reaction temperature and reaction time on the yield of bis(hydroxyethyl terephthalate)(BHET) are investigated. The conversion of PET and yield of bis(2-hydroxyethyl terephthalate) (BHET) reach about 92.6 % and 82 % under the optimal experimental conditions. The properties of the glycolysis products have been characterized by scanning electron microscopy (SEM), infrared spectroscopy analysis (IR), differential scanning calorimeter (DSC), thermogravimetric analysis (TG) and high performance liquid chromatography (HPLC). An evolution of the glycolysis reaction is proposed. In addition, the kinetic of PET fiber is investigated. The results indicate that this glycolysis process is a first-order kinetic reaction and the activation energy is 79.3 kJ/mol, which is lower compared to the same reaction process using PET flake from the soft drink bottle.