Highly thermally stable zirconium oxide deposited layered double hydroxide for enhancing flame retardancy of waterborne epoxy coatings

Inspired by the multifunctional adhesion ability of poly dopamine (PDA), ZrO 2 and aluminum magnesium hydroxide (LDH) were combined by PDA, which increased the function of this material in intumescent fire retardant (IFR) coatings. Briefly, PDA was coated on the surface of LDH to improve its dispersion stability in water. Then, the high thermal stability ZrO 2 nanoparticles were immobilized in situ on the LDH/PDA surface to improve the strength and temperature resistance of the char layer by a hydrothermal strategy. The fire protection performance of LDH@PDA@ZrO 2 (LPZ) modified intumescent fire retardant (IFR) coatings was performed by large plate method, thermogravimetric analysis (TGA) and furnace experiments. From the results, the IFR coating loaded with 2.5% LPZ exhibited the lowest backside temperature and the highest heat insulation, which reached 177.9 °C and 64.42, respectively. Besides, the coating exhibited the greatest expansion height (23.65 mm) and expansion rate (18.92), which is significantly higher than that of other coatings. Moreover, the maximum thermal degradation temperature (T max ) and residual char of LPZ 2.5% /EP were significantly higher than other samples. Further, the LPZ 2.5% /EP based sample indicated the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. The residual carbon analysis showed that ZrO 2 nanoparticles and LDH nanosheets remained in the char layer during the combustion process, which is beneficial to increase the strength of the char layer and its barrier effect on heat and oxygen.