A kinetic study of the thermal degradation of cellulose and its derivatives

Abstract

Abstract The kinetics of the pyrolysis of cellulose and its derivatives (2,2‐dichloropropionate and acetate) in nitrogen and air were studied by dynamic thermogravimetry and differential thermal analysis from ambient temperature to 600°C. From the resulting data various thermodynamic parameters could be obtained following the methods of Freeman and Carroll, Broido, and Dave and Chopra. The values of Δ E * for cellulose and its derivatives were found to be in the range 120 to 260 kJ · mol −1 . However, the values of the free energy of activation for the degradation of cellulose and its derivatives are almost the same, i. e. 187 to 199 kJ · mol −1 , indicating that the basic steps for the thermal degradation of cellulose and its derivatives are the same. Based on Scotney's work on the thermal degradation of cellulose triacetate, a mechanism for the thermal degradation of cellulose 2,2‐dichloropropionate is proposed. The IR spectra of the pyrolysis residues of cellulose dichloropropionate indicate that dehydration takes place and a compound containing carbonyl groups is formed.