Recyclable porous core-shell Mn-Co-O flame retardant for improving flame retardancy and smoke suppression of epoxy resin

The development of metal oxide flame retardants that are easy to synthesize, efficient, and recyclable would be more beneficial to circular economy. In this work, a porous core-shell Mn3CoOx was developed to efficiently reduce heat, smoke as well as hazardous gas during the combustion of epoxy resin (EP). Compared with pure EP, the peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke production (TSP), peak CO production rate (pCOPR), and peak CO2 production rate (pCO2PR) of EP/Mn3CoOx are reduced by 47.5 %, 21.5 %, 34.6 %, 17.6 %, 58.6 %, and 55.4 %, respectively. It has been shown that Mn3CoOx not only catalyzes the formation of high-quality char layer but also effectively catalyzes the conversion of hazardous gas products into CO2. Recovery experiments of Mn3CoOx filler in EP composites show that the recovery of Mn3CoOx can reach 90.0 %. This work provides insights into the design of efficient metal oxide flame retardants and ideas for the development of recycled flame retardants.