Combustion behavior of Scots pine (Pinus sylvestris L.) sapwood treated with a dispersion of aluminum oxychloride-modified silica

Treatment of wood with aqueous dispersions of silica that have been modified with aluminum oxychloride (AlOCl) can impart wood water repellence and increased resistance to fungal decay. This study is a comparative survey on the effects of treatment with modified and non-modified silica dispersions in terms of the combustion behavior of the Scots pine (Pinus sylvestris L.) to evaluate the fire risk of this wood utilized as a construction material. The thermogravimetric results showed that treatments with the silica dispersions did not change the pyrolysis temperature of wood polymers, i.e. there was no synergetic interaction between silica and cell wall polymers during pyrolysis. Cone calorimetry (CONE) indicated that the silica-treated wood required longer time for ignition than the untreated control, but wood chars were similar. Treatments with both silica dispersions led to considerable reduction in the heat release (HR) and smoke production, but the cationically modified silica was more efficient than the unmodified silica. These findings were interpreted that incorporation of modified silica did not substantially influence the pyrolysis of cell wall polymers because they have not penetrated the cell wall; they have rather reduced the fire risk via forming a barrier against oxygen access and a thermal protection shield.