Flame retarding mechanism of polycarbonate containing methylphenyl-silicone

The thermal degradation of polycarbonate (PC) containing methylphenyl-silicone with a branched structure (SFR-PC) was investigated by the thermogravimetric analysis (TGA). The decomposition activation energies were determined using the Ozawa method. It was found that the decomposition activation energy and the degradation residue of the SFR-PC at 800 °C in air atmosphere were much higher than those of the PC. The addition of methylphenyl-silicone enhanced the thermal stability of PC and promoted the formation of char. The silicone was found effective in retarding the combustion of the PC. The limited oxygen index of the PC containing 5 wt.% of methylphenyl-silicone was 34%. Surfaces of the SFR-PC before and after combustion were analyzed by energy dispersive X-ray analysis (EDX) and infrared (IR) spectroscopy. Based on these results obtained, the flame retarding mechanism of the SFR-PC was discussed.