To reduce fire hazards and expand high value applications of lignocellulosic materials, lignin-modified graphene nanoplatelets (GnPs) and multi-wall carbon nanotubes (CNTs) thin films were deposited by a Meyer rod process. Lignin promoted the aqueous dispersion of carbon nanomaterials, and served as a fixer to bridge the cellulose microfibers with carbon nanomaterials, which resulted in the formation of a compact layer protecting the cellulosic substrate from the flame and preserving the paper integrity. Lightweight and highly flexible papers with increased gas impermeability were obtained by coating a protective layer of lignin-modified carbon nanomaterials in a randomly oriented and overlapped network structure. Assessment of the thermal and flammability properties of papers containing as low as 4 wt% coatings exhibited self-extinguishing behavior and yielded up to 83.5%, 87.7%, and 120°C reduction in weight loss, burning area, and maximum temperature, respectively, compared to the blank papers. Furthermore, papers coated with composites of GnPs and CNTs pre-adsorbed with lignin showed enhanced thermal stability and superior fire resistance than samples treated with either component alone. These outstanding flame retardant properties can be attributed to the synergistic effects between lignin, GnPs, and CNTs, enhancing physical barrier characteristics, formation of intumescent char, and thermal management of the material. These results provide potential opportunities of using lignin for the development of efficient, cost-effective, and environmentally friendly flame retardants.

Lignin-modified carbon nanotubes/graphene hybrid as efficient flame retardant

255th National Meeting (2018)

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