Sustainable and environmentally friendly bio-based protection against fire

Flame-retardant agents are used to confer fire resistant properties with effects strongly dependent on their ability to form char during the thermal degradation. The char coats the polymeric materials and provides a good barrier against heat and oxygen diffusion, thus reducing the combustion rate of the polymeric materials. Halogenated agents that are used today are toxic and may cause severe health risks. Lignin, due to the high industrial availability, high char yield, aromatic structure and functionality can be used as a flame retardant. The aim of this study is to investigate if lignin can be used as a flame retardant. In our study, a commercially available kraft lignin (BioPiva 395) was chemically modified by phosphorylation reaction with polyphosphoric acid. The incorporation of phosphor groups in the lignin structure was confirmed by Fourier transform infrared spectroscopy (FTIR). The effect reaction-to-fire like Heat Release Rate (HRR) was done using a cone calorimeter. The preliminary results suggest that phosphorylated lignin improved the fire retardancy of coated wood panels.