Thermal degradation of oriental beech wood impregnated with different inorganic salts

Abstract

This study investigated the thermal properties of Oriental beech (Fagus orientalis) treated with (NH₄)₂HPO₄, K₂HPO₄, NH₄Cl and (NH₄)₂SO₄ salts and their mixtures (1:1; w/w) aqueous solutions at 3% concentrations. The effects of different inorganic salts fire retardants on the thermal degradation characteristics of wood samples were evaluated by thermogravimetric analysis (TGA). Based on the TGA curve for untreated beech wood, weight loss takes place at three distinct steps. The impregnation of inorganic salts resulted in higher char yields and additional thermal degradation steps were identified. The highest char yield (80%) was obtained from (NH₄)₂HPO₄-K₂HPO₄ mixture impregnated sample.  Salt mixtures containing phosphates ((NH₄)₂HPO₄ and K₂HPO₄) have remarkable effects on thermal stability of beech wood, whereas NH₄Cl salt lowered the decomposition temperatures and char yield.