THE DEGRADATION AND STABILIZATION OF SOLID ROCKET PROPELLANTS

A brief history of the development of solid propellant rockets is given and the requirements of the ideal solid propellant are considered. After outlining the properties and ageing mechanism of colloidal propellants, the nature of composite propellants is considered in some detail. The different polymers which have been used as matrices in composite propellants are reviewed and the properties of the polybutadiene matrix currently used are discussed. Data on the long term stability of the latter are presented and the ageing mechanism of the polybutadiene binder is considered. Atmospheric oxidation is established as the main ageing process and the factors, including transition metal compounds, which affect the rate of this process are determined quantitatively. The relevance of this information to the prediction of the service life of composite propellants is demonstrated and methods of extending service life are proposed. Finally, the advantages of the new energetic binders based on nitrated oxetanes, synthesised in these laboratories and currently being developed jointly by the Defence Research Agency and the Nobel Explosives Company, are outlined. Preliminary results on the stability of these binders are presented and the processes which are likely to determine their service life, and how they can be attenuated, are discussed.