Bimetallic metal-organic frameworks and graphene oxide nano-hybrids for enhanced fire retardant epoxy composites: A novel carbonization mechanism

The fire retarded intumescent epoxy resin (EP) composites were fabricated with the incorporation of bimetallic metal-organic framework (MOF) and graphene oxide (GO) nano-hybrids (MOF@GO) with intumescent fire retardants (IFR). EP/0.5MOF@GO-9.5IFR composite exhibited a 41% decrease in peak heat release rate, 30% decrease in total smoke production compared to reference sample EP/10IFR. According to in-situ morphology observation and X-ray tomography result, we observed such a novel carbonization phenomenon forming an alternately loose and accumulated structure. The further carbonaceous char analysis indicated the formation of a reinforced structure with fewer pores and excellent insulated property. Temperature test revealed that the synergistic effect between MOF@GO and IFR promoted the construction of the insulated carbonaceous char, which can maintain its temperature at around 400 °C, thus providing sufficient time to build up the alternative reinforced char. Besides, the mechanical property of EP composite was also improved with a 11% increase in the tensile strength compared with that of EP/10IFR. In perspective, the observed carbonization phenomenon opens a window for understanding the mechanism for intumescent fire retardants. [Display omitted]