Hiroto HABU

高エネルギー物質を溶剤なしで液体化することができれば,液体推進剤のさらなる高性能化が期待される.火薬学会高エネルギー物質研究会ではエネルギーイオン液体(EILs)に着目し,次世代高性能液体推進剤としての適用可能性を検討することとした.本研究では高エネルギー酸化剤アンモニウムジニトラミド (ADN) の液化手法について探索し,モノメチルアミン硝酸塩 (MMAN),尿素との共融により,室温で安定なADN 系エネルギーイオン液体推進剤 (EILPs) を得ることができた.化学平衡計算による性能計算によれば,現行のヒドラジンを上回る性能が期待される.熱分解挙動の検討の結果,ADN 系EILPs は加熱によりほぼすべてがガス化し,N2O,NO2,N2,NH3,HNCO,CO2,H2O を生成することがわかった.現在は実用化に向け,物性,性能を実験的に把握し,必要に応じてそれらの改善を進めている.また,構成する物質の特性がEILPs の物性 (融点,密度,粘度など) に与える影響を把握し,EILPs のデザインを可能にすることおよび蒸気圧の低いイオン液体への着火方法が課題である.

In this study we focused Ammonium dinitramide (ADN) based liquid propellant. ADN is one of the high energetic materials. ADN liquid propellant (FLP, LMP) is expected to replace hydrazine, because of its high performance and low toxicity. We made EILs of ADN using eutectic with ADN and additives. They are promising performance increase of propellant since ILs do not use solvents. We focused Hydrogen Bond Donors (HBDs) as one of the additives. It can be prepared by easy method, only mixing both of them and make liquid. To clarify the effect of HBDs on decrease of melting point, melting point of ADN and HBDs mixtures were measured. We found that decreasing of the melting points depend on the HBD's molecular volume.

In this study, we prepared ammonium nitrate (AN)/ ammonium perchlorate (AP) mixed particle using spray drying for the fundamental study on AN/AP-based propellants. We investigated their surface properties and thermal behavior by scanning electron microscopy (SEM) and thermogravimetry/differential thermal analysis (TG/DTA) respectively. In the result of SEM analysis, the shape of the AN/AP particles was almost spherical. In some cases, particle partially aggregated because of moisture absorption by AN. The average particle diameter was approximately 36-38 μm. In the result of TG/DTA, endothermic peaks were observed around 130-230 and 280-375 C and exothermic peak was observed around 230-280 C. From the comparison with the result of AN and AP, it is considered that endothermic peaks were caused by each thermal decomposition. On the other hand, we suggest that the exothermic peak may result from the reaction between AP and AN because it is only observed in the curves of AN/AP. Endothermic peaks derived from crystal structure transformation of AN were observed around 43, 90 and 125 C by thermal analysis of AN and AN/AP. The peak around 90 C of AN/AP was extremely smaller than that of AN, and this suggested that crystal structure of AN might be changed. Keywords: AN, AP, Spray drying, DSC, TG-DTA.

The purpose of this study is synthesis and thermal characterization of polyurethane containing nitro groups and azide groups using 2,2-Dinitropropan-1,3-diol (DNPD). Structural analysis were used by infrared spectroscopy (IR) and hydrogen nuclear magnetic resonance (1H-NMR). Thermal properties were used thermogravimetry-differential thermal analysis (TG-DTA) and sealed cell differential scanning calorimetry (SC-DSC). Synthesis of polyurethane containing nitro groups in following, a mixture of poly tetramethylene ether glycol (PTMG) and 4,4-diphenyimethane diisocyanate (MDI) were stirred at 90 C for 20 minutes. The mixture were provided in to solvent, N,N-dimetylformamide and added DNPD, and then the mixture was stirred at 90 C for 10 minutes. The products were dried in vacuo at 80 C for 3 hours. The IR, C=O stretching vibration (1730 cm(exp -1)), N-H bending vibration (1530 cm(exp -1)) appeared in the IR spectrum. The products exhibited exotherm at temperature range of 297-420 C, and mass loss of 85 % at 500 C from the TG-DTA curves.

In order to obtain a better understanding of the thermal characteristics and combustion characteristics of 1,2,4-triazole-3-one copper complex (TOCu), elemental analysis, infrared spectrometry (IR), X-ray diffraction(XRD), sealed cell-differential scanning calorimetry (SC-DSC), themogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS) and burning test were performed. TOCu was synthesized from 1,2,4-triazole-3-one (TO) and trihydrated copper nitrate (Cu(NO3)2・3H2O). TOCu was obtained as [Cu(2+)(C2N3H3O)2(NO3)(-)2・2H2O]. From the DSC results, the heat of reaction of TOCu was larger than those of pure TO and TO/Cu(NO3)2・3H2O mixtures. The exothermic peak of TOCu sharply became compared with those of pure TO and TO/Cu(NO3)2・3H2O mixtures. It was found that the reactivity of TOCu was improved to compared with those of pure TO and TO/Cu(NO3)2・3H2O mixtures. TG-DTA-MS curves of TOCu were showed from 3 steps of mass loss, exothermic peak and decomposition gases in the temperature ranges were 100-180 C, 200-260 C and 300-360 C. From the results of TG-DTA-MS, the gases evolved from TOCu were determined as N2, H2O, HNCO, HCN, CO2, CO, NOx and NH3 at 100-360 C. From burning test results, the burning rate of TOCu was calculated by pressure exponent 0.6451 based on Vieille's law.

This research aims to reduce the cost of the solid rocket motor production, mainly solid propellant. The production process of the solid rocket propellant are usually employed the multi-batch mixing. However, this study using a peristaltic pump as a mixer will lead to the continuous process. The pump system can mix the powder materials for propellant and we consider that it will make the slurry of the solid propellant efficiently by the mechanism of the fluid dynamics in the pump.

Ammonium nitrate (AN) has problematic properties for industrial application such as high hygroscopicity and crystal structure transformation accompanied by volumetric change. In our previous studies, we prepared spray-dried particles comprising three components: AN, potassium nitrate (PN) as a phase stabilizer, and polymers (e.g. PVA, CMC, Latex), which was confirmed to provide effective moisture proofing. In the present study, the crystal transformation behavior and the thermal decomposition behavior of AN/PN/Polymer particles were investigated by differential scanning calorimetry (DSC). The results showed that phase-stabilized AN could be successfully prepared by the addition of PN. In addition, an intriguing possibility was identified in that CMCA and PVA, which were both added as polymer components for moisture proofing, also acted as phase stabilizers for AN crystal transformation. When the thermal decomposition behavior was investigated, two exothermic peaks were observed at 190-245°C (first peak) and 272.291°C (second peak) in the result of AN/PN/Polymer. It is possible that the first peaks in the DSC curves for the AN/PN/polymer mixtures result from the reaction of AN with melted PVA, or decomposition products and gases derived from CMC and Latex, and the second peak is due to decomposition of AN on its own.

Thermal dissociation model is proposed for the thermal analysis of Ammonium nitrate (AN) on the assumption of one-dimensional inter-diffusion model in a sample pan. AN decomposition was measured with a Pressure thermogravimetric analysis (TG-DTA), and the results well coincide with the simulations which consider the thermal dissociation and the chemical decompositions. The dissociation model needs only one parameter, diffusion coefficient at atmospheric pressure, and then it is simple and useful for the other high energetic materials.

Ammonium dinitramide (ADN) is the promising new energetic oxidizers for solid propellant because of its high oxygen balance and high energy content, and halogen-free combustion products. For practical use of ADN, one of the important characteristics is chemical stability. This study focused on thermal decomposition mechanism of ADN. Its exothermal behavior and decomposition products in condensed phase during constant rate heating were measured simultaneously with differential scanning calorimetry (DSC) and Raman spectrometry. These analyses showed that the decomposition of ADN proceeded via multiple stages. It was found that one of the main reactions at beginning of ADN decomposition is generation of ammonium nitrate (AN). With more heating, not only ADN decomposition but also the reactions involving AN proceeded.

High performance and Low environmental impact is required for the future solid propellants. Many of high energy material (HEMs) compose without halogen atoms. Additionally, the propellants that used HEMs indicate high theoretical propulsion performance through the calculation. Ammonium dinitramide (ADN) is one of the candidates of the new oxidizer for the advanced solid propellant. However, the combustion characteristics of ADN should be understood deeply for the practical use. In this study, the burning rate characteristics of the ADN/AN mixture pellet were investigated to understand the effects of AN mass ratio in the mixture. The results show that the burning rate of the ADN/AN pellet was decreased with increasing the mass ratio of AN in the pellet. Additionally, the burning rate of ADN/AN pellet (AN mass ratio, 20 mass%) was decreased 40 % compared with ADN at 2 MPa.

Combustion characteristics of pelletized ammonium dinitramide (ADN) and ADN-based propellants have been studied. Micron-meter-sized particles of Al, Fe2O3, TiO2, NiO, Cu(OH)NO3, Cu and CuO, and nano-meter-sized Al (Alex) and CuO (nanoCuO) were employed as the additives for pelletized ADN. Only nanoCuO and Alex show the remarkable effects, so they are also added to ADN-based propellant. The binder of ADN-based propellant is thermoplastic elastomer (TP), and three kinds of mixtures (TP:ADN = 30:70, 20:80 and 10:90 mass%) were prepared .The burning rates of pelletized ADN and ADN-based propellants were measured under the pressure range from 0.6 to 6.2 MPa, and the surface temperature profiles were obtained about ADN-based propellants. Nano-sized CuO enhanced the burning rate of pelletized ADN. Alex-incorporated ADN burned with flames even at 0.55 MPa under which pure ADN does not form the flame. Burning rate of non-additive ADN-based propellants has extremely high pressure dependency. In the case of TP/ADN (30:70), burning rate jump are found from the critical pressure approximately 3.2MPa. The temperature profiles of TP/ADN (30:70) were measured, and the combustion structure was discussed. Both nanoCuO and Alex improved the burning rate characteristics, and the pressure exponents are 0.54 and 0.76 respectively.

Ammonium nitrate (AN) shows promise as a gas generator component because of its affordable price.However, handling this compound is problematic because it is highly hygroscopic and hence undergoes aggregation and solidification. In this study, in order to prevent the hygroscopicity of phase-stabilized ammonium nitrate (AN/KN), we prepared particles from a combination of AN/KN and a polymer (moisture-proof agent) by the spray drying technique and investigated the hygroscopicity. A white powder with a particle diameter of about 20.40μm was successfully prepared by spray drying water solutions (or water dispersions) containing AN/KN and each of the three types of polymers. The results of elemental analysis by Scanning Electron Microscope/Energy Dispersive X-ray spectrometry (SEM/EDX) indicated that each component was homogeneously distributed in the particles. Particle aggregation was hardly observed, and the moisture absorption amount was lower than that in the case of the polymer-free (blank) sample. Even under high-moisture conditions, the particles did not deliquesce immediately and retained their original shape, unlike the blank sample.

The cost reduction is currently important for the development of space launch systems. The solid motor side jet system is loaded the low temperature gas generator propellant (GGP) which includes a special purpose material. The combustion gas temperature of GGP should be controlled up to 1400 K because of the system requirement. The objective of this research is to find the substitution of the composition for GGP to reduce the cost. That is why ammonium nitrate (AN) is selected as an oxidizer for GGP. The composition and combustion characteristics of AN based GGP for the launch vehicle side jet system were investigated. The burning rate was measured by the strand burner.

Ammonium dinitramide (ADN) is one of the promising new energetic oxidizers for solid propellant. For practical use of ADN, one of the important characteristics is chemical stability. ADN is known to degrade to ammonium nitrate (AN) during long term storage, which will affect to performance of rocket motor. In this study, to get better information about aging effects on thermal behavior of ADN, thermal behavior and decomposition gases from ADN and nitrates mixtures during constant rate heating were measured. From the results of these analyses about ADN and nitrates mixtures, the exotherm and gas generation at low temperature side could not be observed. Two possible reasons were proposed, decrease in the acidity of the material due to the presence of AN, or inhibition of the acidic dissociation of dinitramic acid by NO3-.

Solid rockets are required `environmentally friendly', `high performance', and `low cost' at the present day. Ammonium dinitramide (ADN) is a new oxidizer for the solid propellants. Ammonium dinitramide is the environmentally friendly oxidizer because ADN has no halogen. Ammonium dinitramide based propellants have higher performance than ammonium perchlorate (AP) based propellants. However, ADN is more expensive than AP. Therefore, we suggested ADN/ammonium nitrate (AN) based propellants. Ammonium nitrate is the very inexpensive oxidizer which has no halogen. The solid propellants are added the metal particles in order to achieve the high performance. However, ignition and combustion characteristics of the metal particles contained ADN/AN based propellants are not investigated. In this research, we investigated reaction and ignition characteristics of magnalium (Mg-Al) particles in ADN / AN. As a result, it is considered that Mg-Al particles reacted with the decomposition products of ADN/AN. Ignition delay time of Mg-Al particles increased with increasing the concentration of AN. Ignition delay time of Mg-Al particles increased at the concentration of AN between 20 mass% and 60 mass%.