Striking effect of nanosized carbon black modified by grafting sodium sulfonate on improving the flame retardancy of polycarbonate

Abstract To improve the flame retardancy of polymer nanocomposites, a grafting strategy to modify carbon black nanoparticles by grafting sodium sulfonate (CB-g-SS) was developed in polycarbonate (PC) system. The grafting reaction for CB-g-SS was evaluated by FTIR, XPS and TGA, respectively. Furthermore, PC/CB-g-SS nanocomposites were prepared, and the striking effect of CB and SS on improving the flame retardancy of PC was investigated. With only 1 wt% of CB-g-SS, the PC nanocomposites exhibited a high limiting oxygen index of 33.1%, and V-0 rating in UL-94 test, as well as significant decrease on the peak of heat release rate (PHRR) by 51.6% in cone calorimeter test. The flame retardancy mechanism was also discussed, which was ascribed to the catalytic carbonization of SS on CB surfaces for promoting the formation of interconnected carbon layer. Thus, this work provides a useful and effective method for preparing high-performance PC nanocomposites.