Effect of modified layered double hydroxide on the flammability of intumescent flame retardant PP nanocomposites

Abstract The dodecyl sulfate intercalated CaMgAl‐hydrotalcites (layered double hydroxides [LDHs]) were successfully prepared by co‐precipitation method, and characterized by X‐ray diffraction analysis, infrared spectroscopy (Fourier transform infrared spectra [FT‐IR]), thermogravimetry (TG‐DTA), scanning electron microscope, and Brunner−Emmet−Teller (BET). The prepared LDHs were added to the intumescent flame retardant (IFR) polypropylene (PP) nanocomposites, and the limiting oxygen index method (LOI), vertical combustion method (UL‐94), cone calorimetry (CCT), and other test methods were used to study its thermal stability and combustion performance. The results showed that when the flame retardant was composed of 23 wt% IFR and 2 wt% O‐SDS‐LDHs, the LOI value of the material was increased to 31.5%, reaching the V‐0 level, and the flame retardant performance was significantly improved. The results also showed that there was a significant synergistic effect between IFR and O‐SDS‐LDHs, which could improve the thermal stability and graphitization degree of PP nanocomposites. In addition, the peak heat release rate, total heat release, and total smoke production of the PP/IFR/O‐SDS‐LDHs system were 177 kW/m 2 , 101 MJ/m 2 , and 15.4 m 2 , respectively, which were 82.2%, 51.0%, and 23.0% lower than those of pure PP, respectively. These improvements could be attributed to the presence of dense and continuous char layer formed by the synergistic effect.