THERMAL-ANALYSIS OF CELLULOSE TREATED WITH BORIC-ACID OR AMMONIUM PHOSPHATE IN VARIED OXYGEN ATMOSPHERES

Thermal analyses (TG, DTG, and DSC) of cellulose treated with diammonium phosphate or boric acid were conducted in atmospheres of differing oxygen concentration (N//2, and 2. 5, 10, 21% O//2 in He). The weight loss process from both untreated and treated cellulose consists of a first, slow stage, a second, rapid stage, and a third, prolonged, char oxidation stage. The first two stages appear to be first-order reactions; their Arrhenius parameters were obtained. Both of the additives accelerate the beginning of the weight loss, increase the char yield, and inhibit the char oxidation. The main weight loss and the char yield for untreated and treated cellulose may be explained by a chain reaction consisting of random-scission initiation, depropagation producing levoglucosan, and grafting termination, all describable by Arrhenius kinetics.