Zn-Al layered double metal hydroxide anchored reduced graphene oxide for enhancing the fire performance of composite coatings

Layered double hydroxides acts as an effective inorganic nano-fire retardant, which is capable of releasing water, carbon dioxide and diluting the concentration of combustible gases when encountering flames, thus providing fire protection. Here, zinc-aluminum layered double hydroxides (Zn-Al/LDH) is uniformly anchored on the reduced graphene oxide (RGO) surface by a simple hydrothermal strategy in order to further enhance the barrier effect of the char layer. The obtained Zn-Al/LDH anchored reduced graphene oxide (Zn-Al/LDH@RGO) hybrids were added to waterborne epoxy resin and their fire resistance properties were measured by large plate combustion test, furnace storage test and thermal weight loss test. The results showed that the incorporation of nano-fillers effectively enhanced the fire resistance of the composite coatings . Among them, Zn-Al/LDH@RGO -based fireproof coatings presented better fire performance due to the active flame retardant mechanism of Zn-Al/LDH and the high barrier property of RGO nanosheets . In contrast, the composite coating with 1.5% of Zn-Al/LDH@RGO hybrids had the lowest backside temperature of 154.3 °C. Besides, the Zn-Al/LDH@RGO/EP (1.5%) coating also exhibited the highest expansion height (16.5 mm), expansion rate (12.13) and the highest char residue rate (32.2%), indicating its highest fire retardant performance.