The effect of a hybrid system of nanoclay and triphenyl phosphate (TPP) on the fire retardancy of a polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend was examined in this study. The nanoclay in the polymers decreased the peak heat release rates (PHRRs) with no significant effect on the ease of ignition and times to extinguishment. Improvements in the flame retardancy were observed only when nanoparticles were used with conventional flame-retardant (FR) additives. Thermogravimetric analysis (TGA), cone calorimetry, and limited oxygen index (LOI)/UL 94 (Underwriters Laboratory) testing were used to investigate the thermal degradation, fire behavior, and flammability of the materials. The results show that when we used a combination of TPP and nanoclay as an FR system, degradation of the polymer blends was reduced as the TGA curves shifted to higher temperatures. PHRR in cone calorimetry testing decreased from 1032 kW/m 2 for the PC/ABS blend to 300 kW/m 2 for the PC/ABS/(12% TPP-2% nanoclay) sample, and the LOI increased from 23 to 35%, respectively. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: [3435][3436][3437][3438][3439][3440][3441][3442] 2011

Summary: Polycarbonate Acrylonitrile‐Butadiene‐Styrene blends (PC/ABS) with flame retardants Triphenyl Phosphate (TPP), nanoclay and their mixtures were prepared in a twin‐ screw extruder. The morphological properties were characterized by X‐ray diffractometry (XRD) which showed the intercalated structure of nanoclay in the matrix. Thermal stability of the samples was studied using Thermogravimetric Analysis (TGA), and the degradation kinetic parameters were determined using various methods including Kissinger, Flynn‐Wall‐Ozawa and Coats‐Redfern methods. It was found that the sample containing both TPP and nanoclay has the highest activation energy. The activation energy order of PC/ABS blends with different flame retardant packages, obtained by Kissinger method agrees well with that obtained by Coats‐Redfern. Cone calorimetry and limited oxygen index (LOI)/underwriters laboratory 94 (UL94) methods were used to investigate the fire behaviour and flammability of materials. The reduced mass loss rate (MLR), peak heat release rate (PHRR) and enhanced LOI of the composite containing mixture system confirmed a synergistic effect of TPP and nanoclay.

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