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Bimetallic metal-organic framework and graphene oxide nano-hybrids induced carbonaceous reinforcement towards fire retardant epoxy: A novel alternative carbonization mechanism

Zhang, Jing, Li, Zhi, Zhang, Lu, García Molleja, Javier, Wang, De-Yi
Carbon 2019 v.153 pp. 407-416
carbonization, computed tomography, coordination compounds, epoxides, flame retardants, graphene oxide, heat, nanohybrids, smoke, synergism, temperature, tensile strength
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.