Kinetics and products from flash pyrolysis of cellulose acetate butyrate (CAB) at 460-600 degrees C

Cellulose acetate butyrate (CAB) was flash-pyrolyzed at 600-1000 degrees C/s to temperatures in the 460-600 degrees C range under 1 atm Ar. By using nonnegative least squares analysis of the data, 11 specific products (CO, CO2, acids, esters, ketenes, aldehydes, and CAB oligomers) were resolved as a function of concentration and time. Ketene and ethyl ketene are the most novel products. The values of the Arrhenius activation energy are 20-45 kcal/mol at 460-520 degrees C +/- 20 degrees C, and 2-13 kcal/mol at 520-600 degrees C +/- 20 degrees C. These data are interpreted as resulting predominately from bulk-phase decomposition reaction rates in the lower temperature range, and from desorption/evaporation rates in the higher temperature range. A global Arrhenius expression that combines these processes is presented to model the kinetic results. (C) 1997 by The Combustion Institute.