Kinetic Studies of the Thermal Decomposition of KDNBF, a Primer for Explosives

KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC, TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where remaining carbonaceous material is converted to CO2. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models.