Abstract
Bamboo leaf-like CuO(b) and flaky-shaped CuO(f) were prepared by the hydrothermal method, and then combined with Al nanoparticles to form Al/CuO(b) and Al/CuO(f) by the ultrasonic dispersion method. The phase, composition, morphology, and structure of the composites were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy scattering spectrometer (EDS). The compatibility of CuO, Al/CuO and nitrocellulose (NC) was evaluated by differential scanning calorimetry (DSC). The effects of CuO and Al/CuO on the thermal decomposition of NC were also studied. The results show that the thermal decomposition reactions of CuO-NC composite, Al/CuO-NC composite, and NC follow the same kinetic mechanism of Avrami-Erofeev equation. In the cases of CuO and Al/CuO, they could promote the O-NO2 bond cleavage and secondary autocatalytic reaction in condensed phase. The effects of these catalysts have some difference in modifying the thermolysis process of NC due to the microstructures of CuO and the addition of Al nanopowders. Furthermore, the presence of Al/CuO(f) can make the Al/CuO(f)-NC composite easier to ignite, whereas the composites have strong resistance to high temperature. Compatibility and thermal safety analysis showed that the Al/CuO had good compatibility with NC and it could be used safely. This contribution suggests that CuO and Al/CuO played key roles in accelerating the thermal decomposition of NC.
Highlights
Nanosize metal oxides exhibit excellent electrical, optical, magnetic, and catalytic properties, because they have high specific surface area and surface energy, and active sites
The differential scanning calorimetry (DSC) thermal analysis method was used to assess the compatibility of different CuO and Al/CuO nanothermites with NC
When compared with the NC, the thermal decomposition peak temperatures of CuO(b)-NC, CuO(f)-NC, Al/CuO(b)-NC, and Al/CuO(f)-NC are lower than that of NC at 0.5 °C, 0.1 °C, 0.5 °C, and 0.4 °C, respectively. These results indicate that there is no reaction at a low temperature between NC and other Al and CuO reactants, and the compatibility of the bamboo Nleaanfo-mliakteeriaCls u20O20(,b1)0, 7f2la5ky-shaped CuO(f), Al/CuO(b), Al/CuO(f) with NC is good
Summary
Nanosize metal oxides exhibit excellent electrical, optical, magnetic, and catalytic properties, because they have high specific surface area and surface energy, and active sites. When the Al/CuO nanothermites are used as a combustion catalyst, it can effectively improve the combustion performance of solid propellants due to the excellent characteristics of high energy density, high burning rate, high temperature of reaction product, and no need for oxygen during the combustion of Al/CuO nanothermites [13–15]. The exothermic degradation of NC exists the potential hazard during the preparation, storage, and use [22,23] It has been extensively studied experimentally and theoretically for revealing the pyrolysis mechanism and improving the energetic characteristics [24]. The DSC method is one of the most commonly used methods, for evaluating the chemical compatibility between components in the mixtures system at high temperatures, and for investigating the thermal safety characteristic and the thermal decomposition behavior of the NC with catalyst [29–35]. The DSC method evaluated the thermal safety characteristic of the NC composite system with CuO or Al/CuO as catalyst, which has the advantages of cheap, small quantity of sample required, and the capability of quickly select samples with better thermal decomposition performance
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