Kinetics of the isothermal degradation of wood in the temperature range 528-708 K

Two sets of thermogravimetric curves of isothermal degradation of beech wood have been measured for temperatures between 528-584 and 573-708 K, respectively. The reduced sample size (layers 150 mum thick) and the moderate temperatures establish a kinetically controlled process. The curves are well described by a global degradation mechanism consisting of three sequential steps. The kinetic constants estimated for the first-order reaction rates are: (1) In A(1) = 10.2 +/- 4.5 s(-1) and E-1 = 76.2 kJ +/- 21.1 mol(-1); (11) In A(2) = 22.5 +/- 2 s(-1) and E-2 = 142.8 +/- 10 kJ mol(-1); and (III) In A(3) = 2.3 +/- 1 s(-1) and E-3 = 43.8 +/- 5.7 kJ mol(-1). Good agreement is obtained with previous dynamic (I and II step) and isothermal (II step) analyses. (C) 2002 Elsevier Science B.V. All rights reserved.