Lifetime prediction of EC, DPA, akardite II and MNA stabilized triple base propellants, comparison of heat generation rate and stabilizer consumption

A lifetime prediction study is carried out on four triple base propellant compositions by artificial ageing. The ageing effects are studied with High Performance Liquid Chromatography (HPLC) and Heat Flow Calorimetry (HFC) in order to find the most effective stabilizer and to evaluate the advantages and disadvantages of both methods. It is observed that the Ethyl Centralite (EC) and Akardite II stabilized compositions are less affected by the artificial ageing than the Diphenylamine (DPA) and N-Methyl-p-Nitroaniline (MNA) stabilized compositions. The DPA- and the MNA-stabilized propellants are not considered to be safe for the next 10 years based on the HPLC results. Based on the HFC results the DPA-stabilized propellant will also be expected to be safe for a period of ten years. HFC is considered as the best way to determine the propellants lifetime, because the method measures the most important effect of ageing, i.e. the heat generation rate of all chemical processes which occur. The heat generation rate gives an indication of the decrease in calorific value as well as the self-heating potential. HPLC measures the stabilizer and stabilizer derivative content. This only gives an indication of the time that the stabilizer will be present in the composition, but does not provide data of the consumed energy or information on the self-heating potential during the evaluation period. Stabilizing effects of stabilizer derivatives may be neglected in HPLC analysis resulting in an underestimation of the safe lifetime.