Research on mechanical properties and fire retardancy of epoxy composites reinforced by fly ash of thermal power plant

Abstract Flame retardants (FRs) play an important role as additives which is applied in a wide range of products because they can inhibit ignition to delay the spread of fire. By adding fly ash (a waste of thermal power plants), we have developed an epoxy resin material with good flame retardant properties. Besides, using the fly ash can reduce the consumption of current flame retardants (organic halogen compounds) and thus meet the environmental safety of flame retardant epoxy resin. For this reason, studies on enhancing the flame retardancy of epoxy resin using fly ash as an eco‐friendly additive have paid more attention. Adding fly ash flame retardant additives to epoxy resin can improve the oxidation resistance of target materials. In this study, fly ash was modified with Ca(OH) 2 to improve its flame retardant ability and compatibility with epoxy resin. The results show that the samples get higher flame retardant when using 30 wt.%, 40 wt.% and 50 wt.% fly ash. Flame retardant is assessed by the determination of the limiting oxygen index (LOI) and the burning rate test according to the UL94 method. The results show that at the mixing ratio of 40% fly ash, the LOI index is 24.4% and the burning rate according to the UL 94HB method is 19.56 mm/min. When increasing the fly ash content from 30 to 50 wt%, the flame retardant ability increases while the tensile strength, flexural strength and Izod impact strength decrease. For the compressive strength, it increases and maintains at a specified level. The results of this study suggest that fly ash would be a capable candidate for petroleum‐based flame retardant additives.