Effect of BNNs/GNNs/IFR Synergistic Flame Retardant on Thermal Degradation Kinetics of Epoxy Resin

Background: The thermal stability of epoxy resin (EP) is poor, and adding intumescent flame retardants (IFR) and synergistic flame retardants to EP is an effective method to improve its thermal stability. Hexagonal boron nitride (h-BN) has high-temperature stability, and flake graphite (FGP) has a high specific surface area, making it an ideal synergistic flame retardant. However, the direct use of untreated h- BN and FGP can lead to agglomeration, so it is necessary to peel off the layers of h- BN and FGP. Methodology: This article simultaneously conducts microwave exfoliation on h-BN and FGP, observes the morphological changes before and after h-BN and FGP exfoliation through scanning electron microscopy (SEM), and combines the exfoliated nano hexagonal boron nitride (BNNs) and graphene nanosheets (GNNs) with EP and IFR to obtain composite materials. The thermal degradation process of EP and its composite materials is studied using a thermogravimetric analyzer. The thermal degradation kinetics activation energy of EP and its composite materials was calculated using the Starink method and Broido method, and the mechanism function of the reaction was determined by the Phadnis method. Results: The BNNs/GNNs after microwave peeling have a sheet-like shape. EP and its composite materials exhibit similar degradation processes, with activation energies obtained by the Starink method of 165.06 kJ/mol, 162.75 kJ/mol, and 152.00 kJ/mol, 151.80 kJ/mol, respectively; The activation energies obtained by the Broido method are 95.50 kJ/mol, 58.40 kJ/mol, and 56.68 kJ/mol, 56.41 kJ/mol; When G (α)=α 2, the Phadnis method obtains a linear relationship between G ';(α) and 1/T. Conclusion: The microwave method has a good peeling effect on h-BN and FGP. Starink and Broido';s methods showed that the addition of IFR reduced the activation energy of EP composite materials, and the addition of BNNs/GNNs further reduced the activation energy. Phadnis';s method determined that the thermal degradation mechanism functions of EP and its composite materials are first-order diffusion reactions.