Popis: |
Thermal decomposition of propellants limits their safe and reliable service life. Under certain conditions propellants decomposition may become autocatalytic and can lead to the well-known phenomena of self-ignition. It is therefore of great importance to determine accurately propellant stability at a given moment of storage time, as well as to predict with sufficient accuracy whether or not a propellant will ignite under given conditions. Decomposition causes decrease of relevant propellants' properties: decrease of nitrocellulose molar mass, decrease of stabiliser content, decrease of specimen mass, change of mechanical and ballistic performances, etc. Thus, the quality of propellants, i.e. their stability, may be quantified and judged by measuring the changes of these properties. In this paper we have studied thermal properties of several stable and unstable double base propellants in order to see if there are such changes in thermal properties that can be used in propellants stability assessment. Thermal properties were studied applying the non-isothermal differential scanning calorimetry (DSC) measurements. It was found out that DSC curves of stable and unstable double base propellants, obtained under the same experimental conditions, differ considerable. Also, it was found out that the information obtained from DSC measurements are in reasonable agreement with the results obtained by some other tests for propellants' stability determination - the heat test at 100 oC and the stabiliser concentration determination test. These suggest that DSC results can help in propellants stability judgment. |