Combustion of waterborne intumescent flame-retardant coatings with hybrid industrial filler and biofiller

This paper presents the combustibility and thermal stability of an intumescent coating system, which incorporates rice husk ash (RHA) and eggshell as abundant by-products, with two other industrial fillers, namely TiO2 and Al(OH)3. Evaluation was performed using cone calorimeter test at 50 kW m−2 and TGA. Experimental results indicated the influence of fillers on the combustibility properties of coating samples and the decomposition rate of coating materials. The TGA results demonstrated that the addition of RHA and eggshell results in the excess residue weight of more than 35% of the total weight loss. The cone calorimeter test results revealed the coating, which consists of TiO2 and RHA, exerts no effect on fire growth because no ignition is observed. The results proved a remarkable fire resistance of waterborne intumescent coating with the addition of RHA and TiO2 which (1) reduces the total heat release rate (HRR) and heat of combustion; (2) increases the carbon monoxide, carbon dioxide, and smoke yields; and (3) releases the lowest amount of gaseous oxygen released. Consequently, the appropriate combination of hybrid industrial fillers and biofillers has significant influence on the combustibility performance and decomposition of the intumescent coating system.