Study On The Synthesis Of Bisphenol-A Co-Polycarbonate With Reduced Birefringence Through Melt Transesterification Process

Polycarbonate (PC) is an excellent engineering plastic for its outstanding properties. Co-polymerization is an important method to reduce its birefringence. In our study, resorcin and 1,4-cyclohexanedimethanol, together with three kinds of anti-oxidants (including CA, BBM and 2246) are used as co-monomers in the production of co-polycarbonate. Among them, resorcin and 1,4-cyclohexanedi- methanol are preferred according to the result of reactivity tests. The two co-monomers are first reacted with DPC respectively to form the oligomers, and then bis-phenol A is added to the oligomers to form the co-polymers. Several factors that influence the preparation of oligomers, including temperature, pressure and catalysts, are studied. The resorcin and 1,4-cyclohexanedimethanol structures are both found in the 13CNMR spectra. The result of analysis shows the molecular weight exceeds 19,000. Compare to the common bis-phenol A polycarbonate, the co-polycarbonate has a lowered birefringence and better melt flow property (MFR).