Thermal behavior of Liquidambar orientalis mill wood before and after extraction processes

Abstract

The effect of extractives on the thermal behavior of Liquidambar orientalis Mill. (storax) wood is studied using thermogravimetric analysis (TGA). To evaluate the effects of polar and apolar extractives on the thermal behavior of wood, sawdust samples from the heartwood of L. orientalis are extracted with either cold water (48 h), hot water (48 h), or ethanol/toluene (1: 2 v/v) (6 h) prior to thermal analysis. Thermogravimetry (TG) curves show that polar and apolar extractives promote char formation, increase the amount of residue, and improve the thermal behavior of L. orientalis wood. In addition, derivative thermogravimetry (DTG) curves demonstrate that thermal degradation of unextracted and cold water-extracted wood samples occurs in a single step, while a two-step degradation pattern is seen for hot water-and ethanol/toluene-extracted wood samples. It is also observed that first degradation reactions in hot water and ethanol/toluene-extracted wood samples occur faster than those in unextracted and cold water-extracted wood samples. Although there are approximately half the number of extracted apolar compounds compared to polar compounds, the removal of both types of compounds affect the thermal properties of L. orientalis wood to the same degree. It is thus deduced that apolar extractives significantly affect the thermal behavior of L. orientalis wood.