Combustion Performance of Nanoboron‐Based Monodisperse Microfluidic Polymer Spheres Plasticized by Erythritol Tetranitrate

By using microfluidic technology and controlling the difference in flow rate between the oil and water phases, highly spherical nB/nitrocellulose (NC)/1,2,3,4‐butanetetraol tetranitrate (ETN) microspheres with a size of approximately 60 µm were prepared, and their structures and elements were characterized by scanning electron microscopy (SEM), energy‐dispersive spectroscopy (EDS), x‐ray diffraction (XRD), infrared (IR), x‐ray photoelectron spectroscopy (XPS), and laser microscopy. The catalytic effect of the microspheres on the thermal decomposition of ammonium perchlorate (AP)/DAP‐4 was studied in detail using thermogravimetry and differential scanning calorimetry (TG–DSC) testing and burst point testing. The combustion performance of AP/perchloric acid‐triethylenediamine ammonium (DAP‐4) before and after the addition of nB/NC/ETN microspheres was studied using a high‐speed camera, a high‐sensitivity IR camera, and a combustion heat measurement instrument. In addition, this study investigated the combustion mechanism of nB/NC/ETN microspheres. After the introduction of nB/NC/ETN microspheres, the thermal decomposition peak temperature of AP/DAP‐4 decreased by approximately 30°C, the thermal decomposition activation energy decreased by nearly 150 kJ/mol, and the reaction rate constant increased from 0.37 to 0.77. The results of the combustion experiments revealed that after the addition of nB/NC/ETN microspheres, the combustion of AP/DAP‐4 became more intense, and the pressurization rate increased sharply from 1.11 to 6.65 MPa/s. As the burning rate increased, the maximum combustion temperature increased from 1728°C to 1902°C, and the combustion heat increased from −6989 to −13 551 kJ/kg. Moreover, the experimental results indicated that compared with microboron (μB)‐based sample, the nanoboron (nB) sample has higher burning rate and combustion efficiency. Therefore, all the experiments simultaneously demonstrated that nB/NC/ETN significantly promoted the thermolysis and combustion of AP/DAP‐4. Therefore, the results of this work indicated that nB/NC/ETN microspheres may have potential applications in hypersonic ramjet engines.