Thermal Deterioration of Wood

Abstract

When wood is heated at elevated temperatures, it will show a permanent loss of strength resulting from chemical changes in its components. The thermal decomposition can start at temperatures below 100°C if wood is heated for an extended period of time. Figure 1 shows that wood heated at 120° loses 10% of its strength in about one month, but i t takes only one week to obtain the same loss of strength if it is heated at 140° ( 1 ). Heating at higher temperatures gives volatile decomposition products and a charred residue. The pyrolytic reactions and products control the combustion process and relate to the problems of cellulosic fires, chemical conversion of cellulosic wastes and utilization of wood residues as an alternative energy source. In our laboratory, the pyrolytic reactions of wood and its major components have been investigated by a variety of analytical methods. Thermal analysis of cottonwood and its