HEAT SHIELDING PERFORMANCE OF MINERAL BASED INTUMESCENT FIRE RETARDANT COATING

The objective of the paper is to develop intumescent fire retardant coatings with additives of talc and alumina and study the thermal performance. Intumescent coating is a fire protection system designed to reduce heat transfer from a fire to substrate to maintain its integrity. The intumescent coatings are based from three main intumescent components of Expandable Graphite (EG), Ammonium Poly Phosphate (APP) and Melamine (MEL). Epoxy resin of Bisphenol-A (BPA) and hardener Triethylene-tetramine (TETA) were used as curing agent. 11 samples were developed with varying filler percentage of talc and alumina. All 11 formulations were burned in furnace oven at maximum temperature of 450°C and expansion of char was observed. Formulation with 3% filled alumina and 2% filled talc produces the highest char expansion of 1874.78% and 1633.33% of its original thickness respectively. The results show that the char expansion percentage was improved with added filler of talc and alumina.
Heat shielding test was conducted to all 11 samples for 60 minutes each and the backside temperature of the steel substrate was logged for every two minutes. The results show dramatic improvement in intumescent effect with added filler of talc and alumina. The best intumescent effect was achieved with formulation A5 and T3 with maximum temperature of 154.6°C and 163.6°C respectively after reaching equilibrium.
A study on the effect of water resistance was conducted on all eleven samples using the gravimetric method. The coatings were immersed in distilled water and weighed every 24 hours for 168 hours. The weight changes were measured. It is found that small pores and surface damages appeared on alumina filled coating and no defect was found on talc filled coating.