INTRODUCTION 



Fire is an integral part of the natural environment and a constant threat to man's 

 surroundings. It has shaped the forests and grasslands and provided mankind with heat, 

 power, and one of his most devastating weapons. In order to understand fire in its many 

 potential roles we must determine the processes involved in conversion of fuels to 

 volatile compounds, which in turn undergo combustion. An essential part of this process 

 is the initial breakdown and pyrolytic reactions of fuel before it burns. This study 

 was initiated, using modern chemical methods, to help lay the groundwork for research 

 leading to the identification of these reactions. 



This information will be helpful for coping with the many types of fires which are 

 a major national problem. In the United States over 150,000 persons suffer nonfatal 

 burns each year and it is estimated that 12,500 lives are lost in fires which represent 

 a 5-billion dollar loss (Broido 1965). During 1966, a total of 2,396,550 fires of all 

 types caused $1,860,500,000 in property damage (National Fire Protective Association 

 1967). This included 970,000 building fires. During the same period, fires burned 

 4,574,389 acres of forest lands (IJSDA Forest Service 1967). 



The majority of these fires involve wood and wood products, generally referred to 

 as cellulosic fuels. Cellulosic fuels are not flammable as such, but in the presence 

 of a sufficiently powerful source of ignition they undergo pyrolysis and produce vola- 

 tile compounds which burn in the gas phase and result in the propagation of flaming 

 combustion. The purpose of this study is to identify the major compounds resulting 

 from the pyrolysis of cellulose, hemicellulose, and wood. With the addition of 

 thermalanalysis of these fuels, we hope to determine the interaction among the compo- 

 nents undergoing pyrolysis. This should tell us whether studying the thermal properties 

 of the components of wood is a valid technique for the study of the thermal properties 

 of whole wood. Because knowledge of the pyrolysis mechanisms hopefully will lead to 

 the design of efficient flame retardants, a portion of this study deals with the effect 

 of zinc chloride and sodium hydroxide on the pyrolysis of wood and its components. 



It is a difficult task to identify these major compounds because of the complex 

 chemical composition of wood, which in addition to cellulose also contains hemi- 

 celluloses, lignin, extractives, ash (inorganics), and other extraneous materials. 

 Furthermore, the pyrolysis processes generally involve many concurrent and consecutive 

 reactions. Therefore, the only hope for identifying these mechanisms lies in a system- 

 atic approach involving analysis of a selected wood and its components and studying the 

 pyrolytic behavior of each component individually and collectively. 



Fire may be defined as the interaction of fuel, energy, and environment. The 

 chemistry of fire deals with the interaction of fuel and energy and consists mainly of 

 the pyrolytic reactions which lead to flaming combustion. 



THE PYROLYSIS OF CELLULOSIC MATERIALS 



The pyrolysis of cellulosic fuels has been recently reviewed by Shafizadeh (1968) . 

 This review covers a broad range of related subjects, including the historical back- 

 ground and the currently available information on the primary and secondary thermal 

 reactions involved in the pyrolysis of cellulose. 



1 



