Researchers found that the addition of 5% alkaline lignin to water-based intumescent coatings results in an optimal formation of a protective char layer during combustion.

At a concentration of 5%, the alkaline lignin promoted the formation of an ideal char layer during combustion. The chemical structure and durability of the phosphorus–carbon structure in the intumescent coatings were investigated through Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance analysis (13C and 31P). The analysis results reveal that intumescent coatings containing 5% alkaline lignin were more effective in reducing flammability than those containing higher concentrations of alkaline lignin.

Journal of Coatings Technology and Research, Volume 21, pages 611–622, (2024)