Enhancement of stabilizing properties of double-base propellants using nano-scale inorganic compounds.

The use of inorganic stabilizers for double-base propellants in literature is scanty; therefore five samples (S(1)-S(5)) of different percentages (2-4%) of nano-clinoptilolite were investigated as new inorganic stabilizers for double-base propellants (DBPs). The grain size of clinoptilolite stabilizer played an important role in the stabilization effect. As the grain size of stabilizer decreases, the surface area of stabilizer increases and the ability to absorb pronounce amount of hazardous nitrogen oxides increases. In this work clinoptilolite in nano-scale (30 nm) has been used to obtain higher stabilizing effect for DBPs. The evaluation process has been performed through the classical thermal stability tests (Bergmann-Junk and calorimetric tests), in comparison with thermal analyses measurements (TGA and DSC) and kinetic parameters calculation such as activation energy (E(a)), enthalpy of activation (ΔH*), Gibbs free energy of activation (ΔG*), entropy of activation (ΔS*) and frequency factor (A), which calculated using Coats-Redfern and Horowitz-Metzger methods. The results for the new stabilizers were compared with that for the classical one (N,N-diethyldiphenyl urea, C(1)). It has been found that the samples containing new stabilizer with percentages (3.0, 3.5 and 4.0%) showed better stability effect for DBPs than the classical one. The efficiency of stabilization of each inorganic stabilizer to DBPs is also rationalized and correlated with its structure.