Effect of flame retardants on pyrolysis and combustion of α‐cellulose

Abstract

AbstractIn the combustion of wood, the α‐cellulose fraction contributes most of the flaming; the lignin fraction supports the major part of the glowing. In the present study, thermogravimetric and differential thermal analyses were conducted to determine the affect of low concentrations of flame retardants on the kinetics of pyrolysis and phenomena of combustion of α‐cellulose. The flame retardants investigated—sodium tetraborate, aluminum chloride, potassium bicarbonate, and ammonium phosphate—were found to lower the active pyrolysis temperatures and increase the yield of chars. The kinetic data obtained by then no gravimetric analysis of the treated ‐cellulose in vacuum suggest that at least two mechanisms :ire involved. The early stage is controlled by pseudo‐zero‐order and the late stage is of pseudo‐first‐order. Sodium tetraborate and aluminum chloride caused little reduction in activation energies. Ammonium phosphate decreased the activation energy mostly in the early stage. Potassium bicarbonate lowered activation energies of both stages. Further thermal analysis in helium and oxygen showed that flaming combustion of α‐cellulose was substantially reduced by treatment, and its exothermic peak occurred near the end of pyrolytic volatilization. The heat of pyroiysis was reduced significantly by treatment. The heat of combustion is distributed to a wider temperature range, and the maximum intensity of flaming was much reduced by treatment.