This work uses the change of elongation with temperature in a composite solid propellant to assess its shelf life for the air and nitrogen atmospheres applying two methods for the temperature parameterization of the measured quantity, the Arrhenius and Berthelot equation. The samples of the composite propellant contain aluminum (Al), ammonium perchlorate (AP), and hydroxyl-terminated polybutadiene (HTPB) as well as curing agent toluene diisocyanate (TDI), which were aged at three temperatures 323.15, 333.15, and 343.15 K during 15, 30, 60, 90, and 120 days. Stress-strain curves for the samples are inves-tigated to study the effects of the atmospheres of air and nitrogen on the samples. The ratio of the changes in percentage elongation (ɛ) to the initial value of percentage elongation (ɛ r ) is the degradation criterion, which is defined as a reduction of the elongation to less than 50 %. The calculated activation energy by the Arrhenius method is 80.48 kJ mol À 1 for the air atmosphere. The shelf life of the samples were found to be 7.912 and 7.906 years (air atmosphere) to 23.38 and 23.36 years (nitrogen atmosphere) as well as Arrhenius and Berthelot methods, respectively.

Explosives containing metals and the other solid particulates have wide applications in air-blast and underwater explosives. Due to the non-ideal behavior of these explosives, available complex computer codes and empirical methods cannot usually provide a reliable estimation of their detonation velocity. Large experimental data of detonation velocity (392 experimental data) corresponding various types of ideal and non-ideal explosives were collected from different sources to derive a general correlation. The new model assumes partial secondary reactions of metal and active particulates with gaseous products. Optimum values of different products are obtained by maximizing the coefficient of determination (R 2) of the correlation and minimizing the mean absolute percentage error (MAPE) of the calculated results from experimental values of detonation velocities. The MAPE values of the new model and one of the best available methods are 3.55 and 11.16 respectively, for 90 non-ideal explosives, which confirm much high reliability of the new method.

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