Paper and paper based products are inherently flammable due to their nature. Despite their many applications, the highly flammable character of cellulose fibers suppresses their applications. In an effort to impart flame-retardant properties to individual wood fibers, layer-by-layer (LbL) technique is exploited to manufacture intumescent nano-coating thin film (25 nm) consisting of chitosan and poly(vinylphosphonicacid). In order to obtain a better understanding of the build-up of multilayers on pulp fibers, model cellulose surfaces have been used. The adopted deposition conditions were employed to treat pulp fibers prior to sheet preparation. The effect of deposited amount of polymer on flame-retardancy was investigated using horizontal flame test (HFT) and cone calorimetry as a function of the number of bilayers deposited. The nano-coating can enhance the char forming ability of pulp fibers and paper made of 20 bilayers coated fibers showed self-extinguishing during flammability test even though the totally added amount of chemicals was less than 15 % by weight. Scanning electron images of paper after flammability test showed the formation of protecting char layer on individual pulp fibers. Cone calorimetry revealed a significant reduction (up to 49%) of the peak heat release rate with the increased number of deposited bilayers. With this technique it is possible to create an environmentally friendly, biocompatible and non-toxic fire retardant system that can be applied to cellulose fibers and fibrils to create fire resistant wood-fiber based materials (e.g paper, foam, aerogel). We have recently shown that wet-resilient low density aerogels of cellulos nanofibrils (CNF) can be successfully treated with our recently developed filtration technique (Hamedi et at, Angewandte Chemie.(2013) 52,1-6) to prepare flame retardant, low density CNF materials.

Flame-retardant paper from wood fibers functionalized via layer-by-layer assembly

251st National Meeting (2016)

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