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

The influence of relative humidity on the degradation of a nitrocellulose-based propellant with ethyl centralite as stabilizer was investigated. For this kind of material, long term safe storage – maybe decades – is required and various relative humidity conditions can be found. The investigation of chemical integrity only based on accelerated ageing by heating is not sufficient to make secure predictions of the degradation in real conditions. The propellant was aged in different conditions of relative humidity and temperature in order to evaluate the influence of relative humidity on the stabilizer consumption and the consequent chemical integrity. The residual stabilizer was quantified by HPLC analyses. The degradation behavior 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, allows one to propose an optimum range of relative humidity for long term storage.