Synthesis and properties of a fire-retardant coating based on intercalated expandable graphite-modified cellulose for steel structures

In order to improve the performance of intumescent fire-retardant coatings for steel structures and to reduce the defects of the insulating carbon layer (Expanded carbon of fire retardant coatings after thermal degradation.), which usually undergoes cracking and falls off during combustion, we designed a new multifunctional intercalated expandable graphite-hydroxypropyl methylcellulose-uracil ketone (EG-HPMC-UPY) system by ultrasonication. Infrared analysis showed that the 2-ureido-4[1H]-pyrimidinone (UPY) groups were evenly distributed in the coatings to form a large number of reversible covalent and non-covalent bonds; this induced self-healing characteristics in the fire-retardant coatings. Scanning electron microscopy showed that EG expanded into worm-like shapes and intercalated with cellulose in the expanded carbonaceous layer, thus making it more compact and denser. The thermogravimetric analysis and cone calorimetry analysis showed that the weight loss rate and heat release rate of the fire retardant coating added EG-HPMC-UPY decreased by 13% and 65. During fire-resistance tests, it was observed that the temperature of the back and front of the steel plate coated with the fire-retardant coating containing intercalated EG-HPMC-UPY stabilized at 85 and 400 °C, respectively, which values are far lesser than the critical temperature of static equilibrium stability of structural steel (550 °C). Furthermore, the carbon layer formed during combustion did not fall off or crack, thus indicating the excellent flame retardancy potential of the developed coating. Finally, this study describes a new and effective way to improve the fire performance of intumescent fire-retardant coatings for steel structures.