Influence of hybrid functionalized graphite nanoplatelets-tripolyphosphate on improvement in fire protection of intumescent fire resistive coating for steel structures

Functionalized graphite nanoplatelets (FGNP) were modified with tripolyphosphate (TPP) as a thermal oxidation inhibitor. The hybride nano-particles (FGNP-TPP) effects on improvement of fire retardant properties of a traditional intumescent fire retardant (IFR) formulation were investigated. FT-IR results showed that TPP was linked to FGNP nano-particle by hydrogen bondings. TEM image showed homogenous dispersion of FGNP-TPP nano-particles in epoxy. Thermogravimetric analysis (TGA) in air showed the oxidation onset temperature of FGNP was increased by approximately 125 °C in the presence of TPP. Incorporation of 2 wt.% of FGNP-TPP into the traditional IFR coating increased the LOI value from 27.1 to 32. Also, a crack free char with high adhesion to the metal substrate was observed in bunsen burner test which increased the time of failure from 43 to 94 min. The results showed the hybrid nano-particles can improve the thermal oxidation stability of the IFR coating at higher temperatures (900-1000 °C) leading to improved char strength, char adhesion, char morphology, residual weight and fire protection properties.