Gases Evolved by the Thermal Decomposition of Paper

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Abstract
Curves are given to show the rate of evolution of gas by the thermal decomposition of paper as a function of time, and also the dependence of rate upon temperature. The temperature dependence of the rate is in approximate agreement with the Arrhenius formula for reaction velocities. The thermal decomposition reaction apparently has two activation energies, one (33,500 calories) applying to the initial condition of the paper and the other (39,500 calories) applying to a condition reached after protracted heating. The gases evolved consist of . Water vapor is the most prominent constituent of this mixture. This fact has a bearing upon the drying of paper. Water vapor coming from the thermal decomposition of cellulose cannot be distinguished directly from water vapor coming from the adsorbed state in the paper. It is suggested that the and coming off in association with the water provide a means of recognizing an “end point” in the drying operation. When the ratios of these three constituents of the gas mixture first become reasonably constant, the paper may be considered to be as dry as it is possible to make it at the temperature prevailing, without change of its composition. Curves are given to show what degree of correlation exists between the temperature dependence of the aging process, as expressed in changes of tensile or folding strength, and the temperature dependence of rate of gas evolution. If the amount of gas evolved is taken as a measure of the amount of thermal decomposition which has taken place in paper, the degree of thermal decomposition can be put on the same footing as the degree of dryness, in investigations of the properties of nearly dry paper.

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