Can green nitrocellulose-based propellants be made through the replacement of diphenylamine by the natural product curcumin?
Rodrigo Leonard Barboza Rodrigues, Pedro Augusto Gomes Buitrago, Nami Lavigne Nakano, Fernando Cunha Peixoto, Maurício Ferrapontoff Lemos, Tanos C. C. França, Letivan Gonçalves de Mendonça-Filho
Abstract
This research evaluates the feasibility of replacing diphenylamine (DPA) with the natural product curcumin as a stabilizer in samples of nitrocellulose-based (NC-based) propellants. The stability analysis was performed using heat flow calorimetry, as described in STANAG-4582, as well as the most traditional stability testing protocols: the German test, Bergmann–Junk test, and the Storage test. Ballistic parameters were evaluated using a closed vessel ballistic test and samples underwent Scanning Electron Microscopy (SEM). Also, the Pressure Vacuum Stability Test (PVST), Differential Scanning Calorimetry (DSC), and Isothermal Thermogravimetry (TG) to evaluate the homogeneity, stability, and compatibility with NC were performed. The ballistic parameters were evaluated using a closed vessel ballistic test. All samples of propellants stabilized with curcumin passed the stability test criteria performed in this research, with better scores than the propellant sample stabilized with DPA, which was used as a reference. However, the estimation of ballistic parameters indicated that the deflagration of the propellant stabilized with curcumin exhibits some delay when compared to the reference sample, which can be easily overcome by adjusting the propellant grain dimensions, especially the thickness. Finally, an HPLC analysis method was developed to identify and characterize this new Single-Based (SB) propellant stabilizer. This method was shown to be effective, fast, accurate, and adequate to comply with the stability criteria proposed by the AOP-48 standard, especially because of the depletion of the stabilizer concentration after artificial aging. We believe that our results are promising and support the proposal that curcumin can replace DPA as a stabilizer for SB propellants.