Improvement in Thermal Stability and Study of Degradation Kinetics of C4 Explosive in the Presence of Irganox 1010 Antioxidant

C4 composition is a conventional military explosive formulation based on cyclotrimethylenetrinitramine explosive (RDX) and polyisobutylene binder (PIB), which some environmental factors such as thermal and oxygen lead to change in its color and physical characteristics. Using anti-oxidant to reduce the impact of environmental factors and increasing the stability of materials such as C4 during their storage and applications is the very useful. In this research, the effect of different concentrations of Irganox 1010 antioxidant on thermal degradation and stability of PIB and C4 at different temperatures was investigated using ultraviolet-visible (UV-Vis.) absorption spectroscopy, colorimetric histograms, thermal analysis and attenuated total reflection (ATR) infrared spectroscopy techniques, then the quality, absorption and color of the materials were studied quantitatively. Also, the necessary kinetic analyses were evaluated by Arrhenius method to estimate the rate constants and activation energies (Ea) of the thermal degradation reactions, from accelerated aging results on C4 and PIB at different temperatures. The results show that presence of antioxidant in the mentioned materials leads to 2-3 times reduction in the degradation and color change kinetics, and also increasing of activation energy of reactions. In the presence of 0.4 wt. % antioxidant, activation energies are increased from 67.4 to 97.8 kJ/mol for PIB, and from 117.88 to 136.80 kJ.mol for C4. Moreover, the chemical lifetime of C4 based on the color change, predicted using Vant-Hoff equation, in the temperature of 80.0 °C and the presence of 0.4 wt. % antioxidant, are changed from 1.3 to 25.0 years.