Preparation and Properties of Fire-retardant Epoxy Resin Containing an Environmentally Friendly Bio-based CS@SA@ZIF-67 Core-shell Nano-hybrid

In this study, a novel CS@SA@ZIF-67 core-shell nano-hybrid was synthesized using zeolitic imidazole framework-67 (ZIF-67) as a template and CS@SA@ZIF-67 as a modifier. Then, flame-retardant nanocomposites (EP/CS@SA@ZIF-67) were obtained by combining the hybrid with epoxy resins. The microstructure and morphology of CS@SA@ZIF-67 and the residual chars were explored using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the effect of the obtained hybrid materials on the fire performance of the epoxy resins was characterized. Compared with the flame retardant system composed of ZIF-67 and pure EP, the hybrid flame retardant composites exhibited low total heat release and smoke production. The thermogravimetric analysis (TGA) results showed that the maximum thermal decomposition temperature of the EP/CS@SA@ZIF-67 based composite coating was stabilized at the highest value (378.2 and 563.9 °C) so that the introduction of CS@SA@ZIF-67 could improve the thermal properties of the EP/CS@SA@ZIF-67 composites to a certain extent. Meanwhile, the cone test results indicated that the peak heat release rate pHRR of the CS@SA@ZIF-67 filled EP composite was reduced by 18.43% compared to that of pure EP, implying enhanced flame retardancy. The enhanced thermal stability and flame retardancy of the CS@SA@ZIF-67 composites were mainly ascribed to the catalytic effect and carbonization ability of CS@SA@ZIF-67.