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Fluororubber-modified aluminum (AlF) was investigated by core–shell heat transfer model and compared with traditional aluminum with oxide shell (AlO) in terms of heat transfer effect on the reaction behavior of aluminum. Reaction delay behaviors of both AlF and AlO were calculated with diameter ranging from 200 nm to 3.2 µm at different environment temperature. Calculation results showed that AlF got the upper hand over AlO in terms of reaction delay. In the same heat transfer condition, AlF could participate in the reaction with significantly shorter delay time than AlO, which benefits the energy release of the aluminum. Ceiling shell thickness of AlF was determined according to the basic timescale and temperature profile of the explosive reaction zone. Detonation velocity test of AlF was performed with two kinds of AlO as comparisons. Test proved the AlF exhibited higher reactivity than nanoaluminum. Besides, formulation with AlF showed higher detonation velocity than that with AlO, which on the other side verified the reliability of the heat transfer model. Finally, reaction model of AlF in detonation environment was proposed containing three main procedures. [ABSTRACT FROM AUTHOR]

As a kind of energetic plasticizer, ester-terminated glycidyl azide polymer (GAPE) has a potential for being mixed with energetic binder glycidyl azide polymer (GAP) to enable the system a higher overall energy level. To determine whether the mentioned system can be put into practical use, TG-DSC-MS-FTIR was applied to characterize thermal behaviours of GAP, GAPE and 50/50 GAP/GAPE mixture, and VST was used to decide the compatibility of GAP and GAPE. It turns out that GAPE is compatible with GAP. Decomposition of the mixture can be divided into two steps, rapid decomposition with obvious heat release and self-catalysis decomposition, showing the same tendency with the decomposition of GAP and GAPE. Based on the heating rate of 2, 5, 10 and 15 °C min−1, the kinetics triplets of the three samples’ decomposition were calculated, and the decomposition mechanism was obtained. Results show that the decomposition process was governed by the decomposition of GAPE, which started with the scission of -N3. The critical temperatures of thermal explosion of GAP, GAPE and the mixture were also calculated. Substituting the critical temperature to the reaction rate equation to verify the decomposition process, the dominating role of GAPE in this decomposition of mixture was affirmed. Therefore, GAP/GAPE mixture has a promising future in high-energy propellants/explosives. [ABSTRACT FROM AUTHOR]

Nitrate ester plasticized polyether (NEPE) propellant has attracted considerable attention as a kind of high-energy propellant. To investigate the evolution of thermal properties of NEPE propellant during storage life, TG-DSC-MS-FTIR was used to determine the thermal behaviors of the propellant samples before and after 5-year natural storage. It was found out that both samples experience five reaction steps and they are attributed by the evaporation and O-NO bond breaking of nitrate, crystal transition of HMX and thermal decomposition of plasticizer, HMX and ammonium perchlorate. Decomposition process and temperature ranges of each step maintain consistency, but nitrate ester tends to decompose more than evaporate after storage. In the meantime, the area of DSC peak formed in the third step noticeably increased, which accounts for the lower thermal explosion temperature. To further study the decomposition of plasticizer and HMX, their kinetic triplets were solved. It was found out that the activation energy increases significantly on plasticizer decomposition step because of the enlargement of the nitrate's particle size. Therefore, it can be drawn that the decline of NEPE propellant's safety property after storage was contributed by the decomposition step of nitrate ester plasticizer. [ABSTRACT FROM AUTHOR]

The thermal behavior of the energetic material 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-tetracyclo-[5.5.0.0.0]-dodecane (HNIW or CL-20) and its mixtures with aluminum under linear temperature control condition and adiabatic condition were investigated by DSC-TG-MS-FT-IR and ARC. Two different particle sizes of aluminum powder (10 μm and 50 nm) were added into CL-20. The influence of particle size on the thermal behavior of CL-20 was studied by using of these apparatuses. The enthalpies of reaction and onset temperatures were determined for various heating rates. The kinetic parameters were found according to Kissinger method, Ozawa method, and Friedman method based on DSC data. The gaseous products from the decomposition of CL-20 and its mixtures were determined by simultaneous MS-FT-IR experiments. ARC measurements were performed to investigate the thermal stability of the samples. The onset temperature, adiabatic temperature rise, self-heat rate, time to maximum rate, and pressure-temperature profile were found from the data measured by ARC. Based on these results, the catalytic effect of aluminum powder was studied. [ABSTRACT FROM AUTHOR]

In order to optimize formulations of PBX based on Hexanitrohexaazaisowurtzitane (HNIW) and meet the application in mixed explosive, the mold powder of HNIW coated by varied binders was obtained by aqueous suspension technology. Several particle sizes of graphite were added as additive with a 0.5 % mass ratio. The experiment results showed that fluorine resin (FPM) was better than polyurethane and cis-butadiene rubber when the mass percentage of binders was fixed at 4 %. The characteristic height of HNIW/FPM (96/4) mold powder was at 28 cm (2.5 kg hammer), while that of the neat HNIW was at 15 cm merely, and the friction explosion probability fell from 100 to 70 %. The addition of flake graphite with proper grain size would reduce the mechanical sensitivity of HNIW and improved the fluxion property of HNIW-based mold powders. The thermal stability characteristic of HNIW FPM (96/4) and HNIW/FPM/G (96/4/0.5) were studied by thermogravimetric analysis (TG) at 10 °C min, the peak decomposition temperatures were at 251 and 250 °C, which were closed to that of neat HNIW(249 °C) and also identified superior thermal stability of compound. [ABSTRACT FROM AUTHOR]