Flame retardancy and thermal properties of octavinylsilsesquioxane/polycarbonate composites.

Octavinylsilsesquioxane (OVS) as a flame retardant was firstly synthesized, and its structure was characterized by Fourier transform infrared spectroscopy and C and Si nuclear magnetic resonance. It was used to impart flame retardancy to polycarbonate (PC). The flame retardancy and flame-retarding mechanism of the PC/OVS composites were studied by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter (CONE), TG and scanning electron microscopy. The decomposition activity energies of PC samples were studied by the equation of Kissinger. The results showed that PC/1 mass% OVS composites passed UL-94V-0 rating, and its LOI values were 29.4%. Compared with PC, for the PC/OVS composites, the thermal stability and the char yield are increased, but the rate of heat release and the total heat release are much decreased. Scanning electron microscopy revealed that the char properties had crucial effects on the flame retardancy. And the flame-retardant mechanism was also discussed. [ABSTRACT FROM AUTHOR]