Evaluation method for the effect of salts on the elimination of secondary flames of energetic materials by differential scanning calorimetry

Abstract

The effect of LiF, KC1 and KHCO 3 on the thermal decomposition of HTPB/RDX energetic composite (where HTPB is hydroxyl-terminated polybutadiene and RDX is cyclotrimethylene trinitramine) was studied and a method suitable for the evaluation of the inhibitory behavior of alkali metal salts on the secondary flame combustion reaction of HTPB/RDX composite was developed, utilizing thermogravimetry-derivative thermogravi- metry differential scanning calorimetry (DSC) and a multi-channel recorder. It was found that the addition of salts not only limited the extent, but also changed the mechanism, of the decomposition reaction of HTPB/RDX composite. The original one-stage exothermic reac- tion was found to be split into two, three or even more stages by the addition of salts. DSC results proved that the decomposition reaction species are different for the various stages. The mixture of LiF and KHCO 3 had a stronger effect as a retardant of the secondary flame than pure compounds such as LiF, KCl or KHCO 3 alone. The maximum peak temperature ( T m) decreased as KHCO 3 concentration increased, at a concentration of KHCO 3 lower than 35%. A relationship between the DSC data and secondary flame intensity was also found.