Grain poly(ethylene terephthalate) (PET) was depolymerized in pure water by different metal oxides, respectively. The catalytic hydrolysis product of terephthalic acid (TPA) obtained was the same with the no catalytic reaction. The depolymerization rate of PET was seriously influenced of the reaction time and temperature. Especially using stannous oxides as catalyst, with a reaction time of 210 min, a temperature of 200°C and a pressure of 200 psi, the depolymerization rate of PET increased from 59.3 to 90.9% compared with the no catalytic reaction. The morphology of the solid residue indicated that the depolymerization took place on the external surface of the PET grain in the presence of stannous oxide. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Grain poly(ethylene terephthalate) (PET) was depolymerized in pure water in the presence of different catalysts. The product quantity of bis(2-hydroxy ethylene) terephthalate (BHET) and glycol obtained was different from the one without catalysts; especially, using zinc acetate as catalyst, the product obtained was in its pure form with sufficiently high yields. Meanwhile, the depolymerization rate nearly reached to 100%. The purified product was characterized by IR spectroscopy. The depolymerization process of PET reported here was economically viable for the high yields of BHET and glycol. Among all the catalysts used in the reaction, zinc acetate was testified as the most effective one, and the optimal dosage of zinc acetate was 0.4% of the feedstock PET. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A series of poly(ethylene terephthalate) (PET) depolymerization experiments versus time was proceeded under optimal experimental conditions with microwave radiation, in which the temperature was 220°C, the pressure was 200 psi, the microwave power was 260 W, and the ratio of water to PET was 10 : 1. The relative viscosity of the feedstock PET grain and the residual solid products from depolymerization reaction at six different time, respectively, was measured in the solution of 60/40 (w/w) phenol/1,1,2,2-tetrachloroethane. Then the approximate intrinsic viscosity was calculated from linear and exponential extrapolation of reduced viscosity. Molecular weights were calculated by Mark-Houwink's equation, with values of K and α taken from the literatures. The results show that the molecular weights fell dramatically with increasing of reaction time, namely the number average molecular weight from 2.57 × 10⁴ of the feedstock PET to 372 of the remained solid product at 240 min, and the weight average molecular weight of the samples fell from 3.89 × 10⁴ to 408 correspondingly. The intrinsic viscosity decreased greatly with reaction, while the distribution of molecular weight turned to be steady. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008