Layer-by-layer self-assembly of sodium alginate and zinc ions on the surface of graphene oxide to improve the fire protection ability of intumescent waterborne epoxy coatings

In this study, polyethyleneimine (PEI) was first adsorbed on the GO surface, resulting in a positively charged GO/PEI composite. Afterwards, SA and Zn 2+ were loaded on the surface of GO/PEI through a facile route to obtain an organic-inorganic hybrids (GPS@Zn). Among them, the gas phase products of SA delayed the progress of the combustion reaction, while the catalytic carbonization of zinc oxide and the high barrier effect of GO effectively improved the thermal insulation efficiency of the char layer. The fire performance test results showed that the backside temperature of GPS@Zn/EP decreased to 161.2 °C after burning for 60 min. The swelling height and swelling ratio of GPS@Zn based EP remained at the highest value compared to the other samples. In addition, the residual char content of EP loaded GPS@Zn was as high as 31.2 %, which lays the foundation for its high thermal insulation performance. The PHRR, THR, SPR and TSP values of GPS@Zn/EP were 420.2 ± 13 kW/m 2 , 13.2 ± 0.6 MJ/m 2 ,0.078 ± 0.05 m 2 /s and 1.87 ± 0.05 m 2 , respectively, which were significantly lower than the other samples, thus proving its best flame retardant and smoke suppressing properties. The carbon residue analysis confirmed that zinc oxide remained in the char layer, which was beneficial to the improvement of its thermal insulation performance and strength .