Fabrication of zeolitic imidazolate frameworks on layered double hydroxide nanosheets to improve the fire safety of epoxy resin

ZIF@MgAl-LDH hybrids were synthesized by zeolitic imidazolate frameworks (ZIF) and MgAl-layered double hydroxide (MgAl-LDH) via electrostatic interactions. Their structure and morphology were systematically characterized. Then, ZIF@MgAl-LDH hybrids were added to epoxy resin (EP) to study their effects on the thermal properties and fire resistance of the material. The results of TGA showed that ZIF@MgAl-LDH could improve the char yield of the EP composites. The cone calorimetry, smoke density tests, limiting oxygen index (LOI) and UL94 vertical burning test showed that ZIF@MgAl-LDH effectively improved the flame retardancy and smoke suppression of EP. Furthermore, the laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS) results of the char residue showed that ZIF@MgAl-LDH promoted the formation of a char layer with high graphitization and thermal oxidation resistance, which was conducive to the reduction of the fire hazards. This simple treatment of EP may expand its fire safety applications.