Ultrasound assisted methanolysis of polycarbonate at room temperature.

The present work demonstrates an attempt to depolymerize Polycarbonate (PC) at room temperature, which otherwise requires extreme temperature and pressure conditions. It was achieved by the use of ultrasound to intensify the methanolysis reaction of PC. Use of ultrasound showed a significant enhancement in the rate of methanolysis which leads to a reduction in the reaction time from 45 min to 15 min to depolymerize 5 g PC at 30 °C by using 0.1 g NaOH and THF to methanol ratio equaling 3 (w/w). Bubble dynamic study also leads to a conclusion that the highest cavitational enhancement can be achieved at THF to methanol ratio equaling 3 (w/w) which might be due to the fact that this solvent mixture exhibits the least viscosity at this composition. The effect of various parameters such as temperature, NaOH concentration, ultrasonic input power and solvent composition were investigated. The products obtained were bisphenol-A(BPA) and dimethyl carbonate (DMC) which were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and gas chromatography (GC) respectively.