Combustion of cellulose

A demonstration mixture, to show combustion of cellulose by combined oxygen, exploded with great violence soon after ignition. 

George, C. W., R. A. Susott. Effects of Ammonium Phosphate and Sulfate on the Pyrolysis and Combustion of Cellulose Forest Service Research Paper INT-90, U.S.D.A., 1971. 

C. Fairbridge, R.A. Ross, and S.P. Sood, A kinetic surface study of the thermal decomposition of cellulose powder in inert and oxidizing atmospheres. J. Appl. Polym. Sci., 22,497 (1978) also A.R. Horrocks, D. Davies, and M. Greenhalgh, The use of DTA to study spontaneous combustion of cellulose. Fire Mater., 9, 57 (1985). 

Shafizadeh, F. (1968). Pyrolysis and combustion of cellulose materials. Adv. Carbohydr. Chem. 23 419, 474. 

The mechanism of action of flame retardants in thermoplastic materials (polyethylene, polypropylene, polystyrene, cellulosics, PMMA, etc.) is unknown and is certainly quite complex. Broido (7) presented a good example in the difficulties of explaining how fire retardants work. He found that materials which were most effective in preventing flaming combustion of cellulose were also effective in causing sugar cubes to support flame ... 

Fig, 1. —The General Reactions Involved in Pyrolysis and Combustion of Cellulose. 

Application of difiFerential thermal analysis and thermogravimetric analysis techniques to the pyrolysis of cellulose is obviously complicated by the complexity of the reactions involved, and the corrections and simplifying assumptions that are required in calculating the kinetic parameters. Consequently, these methods provide general information, instead of accurate identification and definition of the individual reactions (and their kinetics), which are traditionally conducted under isothermal conditions. The data obtained by dynamic methods are, however, useful for comparing the efiFects of various conditions or treatments on the pyrolysis of cellulose. In this respect, the application of thermal analysis for investigating the effect of salts (and flame retardants in general) on the combustion of cellulosic materials is of special interest and will be discussed later (see p. 467). 

The former variables affect the deposition of heat in the solid fuel and its transient temperature-profile, as well as the diffusion of the volatile pyrolysis products and their distribution and mixing with the surrounding atmosphere. The latter factors influence the nature and sequence of the primary and secondary reactions involved, the composition of the flammable volatiles, and, ultimately, the kinetics of the combustion. Consequently, basic study of the combustion of cellulosic materials or fire research has been channeled in these two directions. 

The variety and number of the known and unknown decomposition products indicate the extent and complexity of the seeondary reactions involved in the pyrolysis and combustion of cellulose. 

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