Phosphorylated lignin as a halogen-free flame retardant additive for epoxy composites

Sustainable, non-halogenatedflame retardants are desired for a variety of industry applications. Lignin, an industrially processed wood derivative, has been examined as a potential sustainable flame retardant additive to polymer systems. Here, the lignin is phosphorylated using a pyridine catalyzed esterification reaction with diphenyl phosphoryl chloride to improve its char forming abilities. The flammability performance of modified lignin-epoxy composites was tested using mass loss calorimetry. With the addition of 10% modified lignin, the peak heat release rate decreased by 40% and the total heat of combustion decreased by 20%.