Effect of relative humidity and absorbed water on the ethyl centralite consumption in nitrocellulose-based propellants

The influence of relative humidity on the consumption of ethyl centralite during the degradation of a nitrocellulose-based propellant was investigated. For such energetic material, long term safe storage – maybe decades – is required and various relative humidity conditions can be found. The investigations of chemical integrity based on accelerated ageing by heating and stability tests are not sufficient to characterize the degradation in real conditions. A sample of propellant was aged in different conditions of relative humidity and the residual stabilizer was quantified by HPLC analyses. The stabilizer consumption at ambient temperature was predicted according to the linearized Arrhenius model. We observed a substantial difference in ethyl centralite consumption by comparing the values obtained for distinct humidity conditions. A possible explanation was proposed. Our results allow one to propose an optimum range of relative humidity for long term storage.