Abstract:

On the basis of comprehensive study of the result of the thermal analysis, the cone calorimetry and the FTIR for wood treated with fire-retardant FRW, by combining the current theory for fire-retardant wood, the fire-retardant mechanism of FRW was proposed. Its main points were as follows: When wood treated with FRW was heated to sufficient high temperature, FRW in the treated wood decomposes to produce noncombustible gas and nonvolatile acidic molten substance, the later have the effects of decreasing the temperature and shielding heat and diluting oxygen in the air, and this diminishes the pyrolysis rate of wood. The acidic products, formed by the decomposition of boric acid and GUP (components of FRW), catalyze the reactions of wood such as dehydration and degradation, the reactions of the pyrolytic products of wood such as condensation, polymerization and reactions to form aromatic structure. This changes the process of wood pyrolysis and promotes charing. The remarkable catalytic charing effect of FRW, which consumedly decreased the heat release of fire-retardant wood, is the key point of its fire-retardant mechanism. Boric acid and GUP take effects at different temperature by different fire-retardant mechanisms, and the two make up for each other, so they are synergistic.

Key words: wood, fire-retardant FRW, fire-retardant mechanism, catalytic charing