Study on depolymerization of waste polyethylene terephthalate into monomer of bis(2-hydroxyethyl terephthalate)

The monomer bis(2-hydroxyethyl terephthalate) (BHET) was obtained with high purity and significant yield by depolymerization of waste polyethylene terephthalate (PET). The glycolysis reaction was carried out at 196 °C with a weight ratio of ethylene glycol (EG) to PET from 0.5 to 6; weight ratio of catalyst to PET from 0 to 1.5% and time of 1-5 h in the presence of zinc acetate as a transesterification catalyst. The optimal conditions are reaction time of 3 h, weight ratio (EG to PET) of 5, weight ratio (catalyst to PET) of 1% and the yield of BHET is 85.6% under these conditions. The glycolysed products were separated into monomer and oligomers and identified by IR, DTA (differential thermal analysis),1H NMR and13C NMR.