Determination of Nitroglycerine Content in Double Base Propellants by Isothermal Thermogravimetry

Thermal methods play an important role among various measuring techniques used in the analysis of explosive materials. These methods are mostly used for the investigation and determination of thermal properties of energetic materials (e.g. melting process, polymorphic transformations, temperature of initiation, etc.), as well as to estimate thermal stability, and to study thermal decomposition. Furthermore, thermal methods can be also used for analytical purposes, such as identifcation of some commonly used high explosives, determination of their purity, determination of phlegmatiser content, etc. The aim of this work was to study the possibility of application of isothermal and non-isothermal thermogravimetry for determination of nitroglycerine content in double based propellants. It has been found out that thermogravimetry can be used not only to distinguish clearly between nitrocellulose and double based propellants, but also for rough determination of nitroglycerine content in double based propellants. The difference between an actual and experimentally determined content of nitroglycerine in double based propellants (i.e. accuracy of the method) is dependent on composition of propellant and data treatment method

Applicability of Non-isothermal DSC and Ozawa Method for Studying Kinetics of Double Base Propellant Decomposition

In order to determine Arrhenius kinetic constants various experimental techniques and testing conditions have been used. Also, various kinetic approaches and data treatment procedures have been applied, resulting sometimes in considerable disagreement in the values of the kinetic parameters reported in literature. Kinetics of decomposition of DB propellants from non-isothermal DSC experiments using unhermetically closed sample pans, and effect of nitroglycerine (NG) evaporation on the kinetic results and kinetics of NG evaporation has been studied by isothermal thermogravimetry. It has been shown by experiments and numerical simulation that at slower heating rates and smaller sample mass NG may completely evaporate before DSC peak maximum, resulting in a higher values of the activation energy (173 kJ/mol). At faster heating rates and larger sample masses certain amount of NG still exists in the propellant at the peak maximum temperature, resulting in lower values of the activation energy (142 kJ/mol). The discontinuity point on the Ozawa plot is connected with the presence of NG in the propellant at DSC peak maximum temperature. This implies that the activation energy obtained using small samples and slow heating rates (173 kJ/mol) corresponds to the activation energy of decomposition of nitrocellulose from DB propellant