Research on the flame retardancy properties and mechanism of modified epoxy resin with graphene-based hybrid

The inherent disadvantage of epoxy resin (EP) is that it is easy to burn, and a large number of toxic and harmful gases are generated in the combustion process, and there is a huge fire hazard. Graphene, a two-dimensional-layered material with physical barrier effects, is used by many researchers to enhance the fire safety of EP, but because of its easy aggregation, it is difficult to prepare high-performance flame retardants. In our work, a high-performance graphene flame retardant was prepared by grafting a hollow zirconium organic frame material onto the surface of graphene. First, zirconium-based organic frame material (UiO66-NH₂) with different particle sizes was prepared by adjusting acetic acid, the hollow organic frame material was etched with sodium tungstate under acidic conditions, and then reacted with organophosphorus and graphene oxide, thus W-UiO66-DOPO-RGO were obtained. The results show that the W-UiO66-3-DOPO-RGO/EP has enhanced smoke suppression and flame retardancy, the LOI value up to 33.5%, vertical combustion class up to UL-94V-0, PHRR and TSP reduced by up to 58% and 42%, respectively. Through the characterization of the condensed and gas phase of EP composites, the relevant flame retardancy mechanism was clarified, which were mainly the synergistic flame retardancy and smoke suppression mechanism among the adsorption of fractional pores of hollow bimetallic MOFs, catalytic carbonization of metals, condensed phase and gas phase interaction of phosphorus elements, and physical shielding of RGO.

Highlights

• A high-performance graphene-based flame retardants were proposed.
• 3 wt% of W-UiO66-3-DOPO-RGO endows EP with excellent flame retardancy.
• The fire safety mechanism of W-UiO66-DOPO-RGO/EP was proposed.