Environmentally friendly intumescent coatings formulated with vegetable compounds

Intumescent coatings have been presented as a great choice for the protection of steel structures against fire due to their ability to provide thermal insulation of the metal substrate by the formation of a protective carbonaceous layer. The carbon source is one of the main components of the intumescent system and usually it comes from non-renewable sources. Therefore, the development of more environmentally friendly alternatives is essential. In this work, epoxy resin coatings were prepared with vegetable compounds (ginger powder and coffee husk) to act as a carbon source in the intumescent system. In addition, the possibility of using zinc phosphate (ZnP) and triphenyl phosphate (TPP) as flame retardants has been verified. The characterization of the coatings was performed through a fire resistance test, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Xray diffraction (XRD) and pyrolysis gas chromatography mass spectrometry (Py-GC-MS). Both vegetable compounds showed potential for application as a carbon source, decreasing the temperature of the substrate when compared to the blank condition. Coatings containing TPP show better behaviour as flame retardants and better expansion than ZnP. Py-GC-MS analysis shows the absence of toxic gases such as CN- and phosphine.