Improving the Thermal and Mechanical Properties of Polycarbonate via the Copolymerization of Tetramethylbisphenol A with Bisphenol A.

Polycarbonate is a widely used engineering plastic. However, synthesis procedures using phosgene produce toxic gases that cause environmental pollution. It is important to improve the performance of polycarbonate by using a green and safe process. Here, we synthesized tetramethylbisphenol A and bisphenol A copolymers by a green, nonphotogas melt-transesterification process using bisphenol A, diphenyl carbonate, and tetramethylbisphenol A as reaction materials. The catalysts required for the synthesis were screened. The chemical structures of the polymerization products were confirmed by an infrared spectrometer and a nuclear magnetic resonance spectrometer. The thermal and mechanical properties of polycarbonate materials were measured through differential scanning calorimetry, thermogravimetry, and an electronic Universal Testing Machine. The results showed that tetramethylbisphenol A copolycarbonate was successfully synthesized by a melt-transesterification process. Moreover, the addition of tetramethylbisphenol A significantly improved the thermal and mechanical properties of polycarbonate. The effects of catalyst dosage, diphenyl carbonate/diphenol molar ratio, polycondensation reaction temperature, and time on the molecular weight of tetramethylbisphenol A and bisphenol A copolymer were investigated, and the optimal conditions were obtained.