Two new energetic coordination polymers (CPs) [Pb(BT)(HO)] (1) and [Pb(DOBT)(HO)]·(4HO) (2) with 1D and 3D structures were synthesized by employing two rational designed ligands, 1H,1'H-5,5'-bitetrazole (HBT) and 1H,1'H-[5,5'-bitetrazole]-1,1'-diol ligands (DHBT), respectively. Thermal analyses and sensitivity tests show that the 3D architecture reinforces the network of 2 which has higher thermal stability and lower sensitivity than that of 1. Through oxygen-bomb combustion calorimetry the molar enthalpy of formation of 2 is derived to be much higher than that of 1 as well as the reported CPs. Herein, more importantly, the heats of detonation (ΔH) were calculated according to the decomposition products of TG-DSC-MS-FTIR simultaneous analyses for the first time. The calculated results show that ΔH of 2 is 23% higher than that of 1. This research demonstrates that 3D energetic CP with outstanding energetic properties can be obtained through efficient and reasonable design.
As a hot research topic, nano-scale energetic materials have recently attracted much attention in the fields of propellants and explosives. The preparation of different types of nano-sized energetic materials were carried out, and the effects of nano-sized energetic materials (nEMs) on the properties of solid propellants and explosives were investigated and compared with those of micro-sized ones, placing emphasis on the investigation of the hazardous properties, which could be useable for solid rocket nozzle motor applications. It was found that the nano-sized energetic materials can decrease the impact sensitivity and friction sensitivity of solid propellants and explosives compared with the corresponding micro-sized ones, and the mechanical sensitivities are lower than that of micro-sized particles formulation. Seventy-nine references were enclosed.
Nanoscale composite energetic materials (CEMs) based on oxidizer and fuel have potential advantages in energy adjustment and regulation through oxygen balance (OB) change. The micro- and nanosized fibers based on nano nitrocellulose (NC)-ammonium dinitramide (ADN) were prepared by the electrospinning technique, and the morphology, thermal stability, combustion behaviors, and mechanical sensitivity of the fibers were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gas pressure measurement of thermostatic decomposition, laser ignition, and sensitivity tests. The results showed that the prepared fibers with fluffy 3D macrostructure were constructed by the overlap of micro/nanofibers with the energetic particles embedded in the NC matrix. The first exothermic peak temperature (Tp) of the samples containing ADN decreased by 10.1 °C at most compared to that of ADN, and the pressure rise time of all the samples containing ADN moved forward compared to that of the sample containing NC only. Furthermore, ADN can decrease the ignition delay time of NC-based fibers under atmosphere at room temperature from 33 ms to 9 ms and can enhance the burning intensity of NC-based fibers under normal pressure. In addition, compared to the single high explosive CL-20 or RDX, the mechanical sensitivities of the composite materials containing high explosive CL-20 or RDX were much decreased. The positive oxygen balance of ADN and the intensive interactions between ADN and NC can reduce the ignition delay time and promote the burning reaction intensity of NC-based composite fibers, while the mechanical sensitivities of composite fibers could be improved.
The fluffy fibers based on nitrocellulose (NC)/ammonium dinitramide (ADN) with high explosives have been fabricated by electrospinning technique. The morphology, thermal stability, combustion behaviors and mechanical sensitivity of NC/ADN-based composite fibers were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), differentialscanning calorimetry (DSC), gas pressure measurement of thermostatic decomposition, laser ignition and sensitivity test, respectively. The results showed that the prepared fibers with fluffy 3D macrostructure were constructed by the overlap of mirco/nanofibers with the energetic particles imbedded in NC matrix. The addition of ADN can accelerate the thermal decomposition with the peak temperature (Tp) decrease by 10.1 oC and the pressure rise time moving forward. Furthermore, ADN can decrease the ignition delay time of NC-based fibers under atmosphere at room temperature from 33 ms to 9 ms, and enhance the burning strength of NC-based fibers under normal pressure. In addition, the impact sensitivities were reduced from 100–56% for NC-based fibers containing CL-20 and from 88–56% for NC-based fibers containing RDX; the friction sensitivities were reduced from 100–64% for NC-based fibers containing CL-20 and from 84–60% for NC-based fibers containing RDX, respectively.
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