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Depolymerization and monomer recovery from polycarbonate (PC) by methanolysis was investigated. Methanolysis with molar ratios of methanol to polycarbonate ranging from 12.5 to 50 was carried out from 170°C to 300°C for up to 30 min. Polycarbonate decomposed into two monomers, bisphenol A (BPA) and dimethyl carbonate (DMC), and two useful by-products, phenol and 4-tertbutylphenol. The percentage depolymerization of polycarbonate increased markedly from 170°C to 230°C and decomposed completely when the temperature was higher than 260°C. Reaction time and molar ratio of MeOH/PC are two other important factors that affect polycarbonate methanolysis. The optimal depolymerization condition of PC was found at 240°C with the molar ratio of MeOH/PC equal to 37.5 and the time of 5 min. Under these conditions, polycarbonate would decompose completely and the monomer recovery of BPA and DMC were 90.7% and 95.2%, respectively.

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