Fire behavior and smoke emission of phosphate-based inorganic fire-retarded polyester resin

The fire behavior and the smoke emission of an unsaturated polyester resin modified by the addition of three phosphorus-based fire-retardant materials (ammonium polyphosphate (APP), silane-coated APP, and melamine pyrophosphate) at two concentration levels (20% w/w, 35% w/w) have been investigated. Scanning electron microscopy, Fourier transform infrared spectroscopy and optical microscopy analysis have been performed to verify the dispersion and the action mechanism of additives within the resin. Results from cone calorimetric tests demonstrated that the incorporation of the fire retardants at 35% w/ w has a strong effect on flammability and smoke suppressant properties with respect to both the neat resin and the loaded systems at 20% (w/w). In particular, the smoke formation and smoke parameters are reduced by 50% and 80%, respectively, leading to the conclusion that APP can be used single-handedly without combination with specific smoke suppressors.