Inspired by the shell of an armadillo-black phosphorus nanosheets weared Ar plasma protective clothing to enhance the fire safety of epoxy resin

Black phosphorous (BP) nanosheets as a novel two-dimensional material have revealed dramatically fire safety promotion in polymer nanocomposite. Herein, plasma cleaning machine (PC), equiped with Ar plasma, was applied to protect BP (PCBP) to enhance the environmental stability of BP. Further, the fire safety of epoxy resin (EP) was enhanced. The molecular dynamics simulation (MDS) results indicate that the values of binding energy between Ar plasma and BP at 0 K, 200 K, 400 K, 600 K, and 800 K were -847.0148, -847.3044, -847.3012, -847.2975, and -847.3035 eV, respectively. It meant that there was a strong electrostatic interaction between BP and Ar plasma, and it was not affected by temperature. Electron Paramagnetic Resonance (EPR) test revealed that the free radical strength of PCBP decreased than BP, suggesting that the environmental stability of PCBP was better than that of BP. The results of cone calorimetry test (CCT) displayed that the flame retardant ability of EP was enormously improved through the addition amount of 1.5 wt % PCBP nanosheets, for instance, the peak heat release rate (pHRR) and the total heat release (THR) were descended by 22.98 % and 16.24 %, respectively. Epoxy nanocomposite with 1.5 wt% PCBP nanosheets can achieve UL-94 V-0 rating level with a limit oxygen index (LOI) of 30.4. Thermogravimetric analysis (TGA) result displayed that the residual weight rate increased by 23.27 %. Raman test of the residual char layer proved that the value of I_D/I_G declined from 4.021 to 3.098, indicating a promotion in the degree of graphitization. These were attributable to the cooperation effect of physical barrier, free radicals trapping and catalytic conversion into char of PCBP.