Abstract:In this paper, the physical and mechanical properties of representative domestic and imported polycarbonate (PC), produced by phosgene method and melt transesterification method and the stability performance after repeated processing were systematically studied. The results shown that there is no significant difference in elongation at break, yield stress, impact strength and melt flow rate (MFR). However, the repeated processing stability of PC is significantly different. The molecular structure, molecular weight and distribution of different PCs were analyzed by GPC and 13C-NMR. Combined with the results of Instron material testing machine, it is found that the higher the proportion of small molecular chains in PC with similar molecular weight, the greater "discreteness" of molecular chains, the worse stability of physical and mechanical properties after repeated processing. Moreover the higher content of branched chains and aryl ketones, the worse of the repeated processing stability. Branched chain and aryl ketone structures exist in the melt transesterification method PC due to Fries rearrangement, but don’t in the phosgene method PC.