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Thermal analysis of cellulose treated with boric acid or ammonium phosphate in varied oxygen atmospheres
Author(s) -
Hirata Toshimi,
Werner Kathleen E.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070330510
Subject(s) - char , cellulose , boric acid , chemistry , oxygen , yield (engineering) , arrhenius plot , arrhenius equation , inorganic chemistry , polymer chemistry , nuclear chemistry , pyrolysis , organic chemistry , activation energy , materials science , metallurgy
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. Boric acid inhibits the first stage and ammonium phosphate promotes it. The effects of oxygen are smaller than those of the additives. Oxygen produces three effects: acceleration of the beginning of the weight loss, an increase in the char yield, and oxidative gasification of the char. However, the dominant of these three effects changes depending on the oxygen concentration. 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.