Fire Performance of Flame Retardant Polypropylene and Polystyrene Composites Screened with Microscale Combustion Calorimetry

Flame retardant polypropylene (PP) and polystyrene (PS) materials were prepared by the incorporation of decabromodiphenyl oxide and Sb2O3 in addition to nanoparticles, montmorillonite clay, and carbon nanotubes (CNTs). Their fire performance was screened with microscale combustion calorimetry (MCC) as well as evaluated by cone calorimetry. The decabromodiphenyl oxide–Sb2O3 system exhibited better efficiency in reducing the peak heat release rate (PHRR) of PP compared to PS in the MCC, whereas the trend was the opposite in cone calorimetry. Introduction of clay or CNTs to the decabromodiphenyl oxide–Sb2O3 system was beneficial in reducing the PHRR of both composites in cone calorimetry; however, a reduction in the PHRR in the MCC was only observed in the PS composites. The thermogravimetric analysis (TGA) studies revealed that the fire results from the MCC for the two types of composites were strongly correlated with their thermal degradation traces. There were poor relationships between the parameters of MCC and cone calorimetry, but good correlation between the temperature difference of the first and second peak of mass loss rate in the TGA, temperature at the PHRR in the MCC, and fire performance index in the cone calorimetry