Synthesis of a novel graphene conjugated covalent organic framework nanohybrid for enhancing the flame retardancy and mechanical properties of epoxy resins through synergistic effect

A novel graphene conjugated covalent organic framework (AGO@COF) nanohybrid was synthesized by solvothermal method and used to enhance the flame retardancy and mechanical performances of epoxy resins (EP) through synergistic effect firstly. It is deduced from thermogravimetric analysis and cone calorimeter results that the obtained AGO@COF nanohybrid improves the flame retardancy of EP significantly. The time to peak heat release rate of EP increases by 17 s, the peak heat release rate and total heat release of EP decrease by 43.6 and 24.3% due to incorporation of 2 wt% AGO@COF. It is referred from thermogravimetric analysis-fourier transform infrared spectrometry results that the release of toxic gases and combustible volatiles during pyrolysis is also suppressed. As for mechanical performance of EP nanocomposites, the storage modulus of EP/2 wt% AGO@COF (34.66 GPa) in the glassy state increases by 23.8% compared with the neat epoxy (28.00 GPa). The possible mechanism for enhanced flame retardant and mechanical performances is proposed according to the test results. This work has opened up a new application for AGO@COF nanohybrid in the field of flame-retardant polymers.