The Pyrolysis of Cellulose at Rates Approaching Those in Burning

Abstract

The thermal decomposition of cellulose was studied by a new thermal method suited to the measurement of faster reaction rates and to the problem of detecting concurrent reactions.

The pyrolysis data for four types of relatively pure cellulose indicated successive supramolecular and molecular decom position steps, either of which may control the decomposition rate contingent upon the temperature history. The molecular decomposition step is interpreted as a first-order depolymerlzation reaction with an activation energy of 401/2 kcal/gmol.

The data for cellulose treated with retardant (1.5 wt% KHCO₂) indicated two principal decomposition reactions. An initial lower-temperature reaction evolved principally H₂O and CO₂ from well-dried samples. The following main decomposition reaction exhibited the same kinetic parameters as the counterpart depotymerization step of the untreated cellulose, but evolved different vapor products.

Tests and analyses of these celluloses at transitional stages of decomposition are summarized. The implications of the data concerning the mechanism by which the retardant functions are discussed.