Intrinsic kinetics of polycondensation reaction for bisphenol A polycarbonate in supercritical CO2

The intrinsic kinetics of polycondensation reaction for polycarbonate synthesized by transesterification between bisphenol-A(BPA) and diphenyl carbonate(DPC) in supercritical carbon dioxide(SC-CO₂) were investigated. SC-CO₂ not only can dissolve phenol, the byproduct of polycondensation, but also can plasticize PC, increase end group mobility, which improve effectively reaction rate. The experimental results showed that, the effect of internal phenol diffusion on overall reaction rate can be negligible as prepolymer particle size lower than 0.143 mm, and the effect of external phenol diffusion limitations can be negligible as CO₂ flow rate up to 15 mL/min. In the first 6 hours, the polymerization reaction of PC is an elementary, the order is second, and the apparent forward reaction kinetics constants were determined at temperatures from 90°C to 130°C, and pressures from 10 MPa to 14 MPa. The average apparent activation energy was 16.4 kJ/mol.