Investigation of the reaction mechanism of 5-Amino-1H-Tetrazole with nitrocellulose using thermal analysis techniques

Abstract

5-Amino-1H-Tetrazole （5AT）, a green energetic substance, has been used in propellants, pyrotechnics, and gas generators because of its high energy density and low sensitivity. However, inferior combustion performance prevents its further applications. Thermal behavior analysis might give direction on controlling combustion properties, which can be successfully optimized by incorporating additional energetic elements. In the present study, an in-depth investigation into the pyrolysis mechanism of 5AT samples incorporating nitrocellulose (NC) was conducted. To achieve this, thermogravimetric analysis coupled with differential scanning calorimetry (TG-DSC) and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) were employed to elucidate the pyrolysis process, while kinetic parameters were determined using three distinct methodologies: two model-free approaches (Kissinger-Akahira-Sunose and Advanced Vyazokovin) and one model-fitting approach (Coats-Redfern). Thermal analyses revealed that all samples experienced a pronounced weight loss accompanied by endothermic reactions within the temperature range of 100–300 °C. The introduction of NC significantly diminished both the enthalpy of reaction and the peak temperatures observed in the derivative thermogravimetric (DTG) curves, findings corroborated by complementary FTIR spectroscopic data. These observations can be attributed to the thermal decomposition of NC, which releases NO₂ and generates heat, thereby facilitating the cleavage of the 5AT ring. Kinetic analysis indicated that the presence of NC reduced the activation energy of the 5AT pyrolysis process; however, it exerted minimal influence on the underlying kinetic model. The pyrolysis behavior of the samples was predominantly governed by the Fn model. Ultimately, the most plausible reaction mechanism for the 5AT-NC samples was delineated. The findings of this study contribute positively to the enhancement of 5AT combustion performance.