CNT modified layered α-MnO 2 hybrid flame retardants: preparation and their performance in the flame retardancy of epoxy resins.

In this paper, CNT modified layered α-MnO 2 hybrid flame retardants (α-MnO 2 -CNTs) were synthesized through one-pot preparation. The structure and composition of the α-MnO 2 -CNTs hybrid flame retardants were investigated by X-ray diffraction, TEM and SEM. Subsequently, the α-MnO 2 -CNTs hybrids were then incorporated into epoxy resin (EP) to improve the fire safety properties. Compared with pure EP and the composites with CNTs or α-MnO 2 , EP/α-MnO 2 -CNTs composites exhibited improved flame retardancy and smoke suppression properties. With the incorporation of only 2.0 wt% of α-MnO 2 -CNTs hybrid flame retardants, the peak heat release rate and total heat release of the composites showed 34% and 10.7% reduction respectively. In addition, the volatile gases such as CO and CO 2 were reduced and the smoke generation was also effectively inhibited. The improved fire safety of the composites is generally due to the network structures and the synergistic effect of α-MnO 2 and CNTs, the catalyzing charring effect, smoke suppression and the physical barrier effect of α-MnO 2 nanosheets.