Flame retardancy mechanisms of phosphorus-containing polyhedral oligomeric silsesquioxane (DOPO-POSS) in polycarbonate/acrylonitrile-butadiene-styrene blends

The flame retardancy mechanisms of a novel polyhedral oligomeric silsesquioxane containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-POSS) in polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends are discussed. The thermal stability of PC/ABS composites with different DOPO-POSS loadings are investigated by TGA and the enhancement of the thermal stability could be found at high temperature range. Their fire behavior is tested by the LOI, UL-94, and cone calorimeter. Excellent flame retardancy of PC/ABS composites have been discovered with 10wt% DOPO-POSS loading. TGA-FTIR, FTIR, XPS, and SEM, respectively, are used to characterize the gaseous products and the condensed residue in thermal decomposition, and the micro-structure of the chars from cone calorimeter tests. The decomposition of PC/ABS with 10wt% DOPO-POSS shows significant changes compared with PC/ABS by TGA, FTIR, TGA-FTIR, and XPS analysis. The enhancement of the thermal-oxidative stability of PC/ABS with DOPO-POSS is attributed to the interaction between DOPO-POSS and PC/ABS at high temperature, which might be the key for improvement of the flame retardancy.