Study of the kinetics of thermal and thermal-oxidative destruction of treated with flame retardants and untreated wood (Part 2)
The choice of flame retardants as additives to water when extinguishing forest fires should be based on a preliminary (laboratory) study of their fire-retardant properties for wood, determining the mechanisms of fire-retardant action. Evaluation of the effectiveness of a particular flame retardant can be carried out by studying the kinetics of thermal and thermo-oxidative degradation of treated and untreated wood. The purpose of this work is to supplement the method for evaluating the fire-retardant effect of flame retardants solutions with methods for studying the rates of smoke aerosol release and its amount during thermal and thermo-oxidative destruction of wood. Quantitative rate estimates of various stages of thermal and thermo-oxidative degradation are obtained by the method of formal kinetic calculation based on experimental data on the rates of smoke aerosol release. The calculation showed that treatment with flame retardants (in this case MgCl2) reduces the activation energy of dehydration and depolymerization processes from 83.68 to 75.31 kJ/mol-1 (for 8% solutions) and to 58.58 kJ/mol-1 (for 35% solutions). This indicates that the halides of magnesium are as catalysts of dehydration in the present case. Kinetic analysis allows to conclude that the treatment of wood with flame retardant (MgCl2) reduces the amount of smoke aerosol released during thermal degradation, and at the same time it accelerates the processes of heterogeneous oxygen enrichment of substances on the surface of the carbonized residue.