| Summary: | Ethylenediamine modified ammonium polyphosphate (EDA-MAPP) and charring-foaming agents (CFA) were prepared using a simple chemical method and further used to make intumescent flame retardant coatings based on epoxy resin. The content of MAPP and CFA was fixed at a ratio of 2:1. Nanoparticles of magnesium aluminate (MgAl<sub>2</sub>O<sub>4</sub> NPs) have been introduced into the flame retardant coating formulation in various quantities to evaluate the promotional action of MgAl<sub>2</sub>O<sub>4</sub> NPs with a flame retardant coating system. The promotional action of MgAl<sub>2</sub>O<sub>4</sub> NPs on the flame retardant coating formulation was studied using a vertical burning test (UL-94V), limiting oxygen index (LOI), thermogravimetric analysis (TGA) and Fourier transform infra-red spectroscopy (FTIR). The UL-94V results indicated that the addition of MgAl<sub>2</sub>O<sub>4</sub> effectively increased flame retardancy and met the V-0 rating at each concentration. The TGA results revealed that the incorporation of MgAl<sub>2</sub>O<sub>4</sub> NPs at each concentration effectively increased the thermal stability of the flame retardant coating system. Cone-calorimeter experiments show that MgAl<sub>2</sub>O<sub>4</sub> NPs effectively decreased peak heat release rate (PHRR) and total heat release (THR). The FTIR results indicated that MgAl<sub>2</sub>O<sub>4</sub> NPs can react with MAPP and generate a dense char layer that prevents the transfer of oxygen and heat.
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