High-performance Propellants Research Articles

In Situ Assembly of 3-(Tetrazol-5-yl)triazole Complexes with Ammonium Perchlorate for High-Performance Energetic Composites.

Advanced energetic composites possess promising properties and wide-ranging applications in explosives and propellants. Nonetheless, most metal-based energetic composites present significant challenges due to surface oxidation and low-pressure output. This study introduces a facile in situ method to develop energetic composites Cutztr@AP through the intermolecular assembly of nitrogen-rich energetic coordination polymers and high-energy oxidant ammonium perchlorate (AP). Morphological analysis reveals the unique structure of Cutztr@AP, where Cutztr is distributed throughout the interior and surface of the AP particles. The nonisothermal thermodynamic analysis reveals a heat release of 2378.2 J g-1 for Cutztr@AP2, outperforming the Cutztr/AP2 achieved through ultrasonic mixing (2000 J g-1). Notably, Cutztr@AP2 exhibits promising combustion and pressure output performances, including a significantly shorter duration, a larger flame area, and higher pressure values. This novel and facile preparation technique and microstructure design approach holds significant promise for high-performance propellants, gas generators, and other related applications.

Unrevealing the role of the sulfonitric media composition on the design and properties of potato starch-based nitrogen-rich biopolymer

In research of crafting high-energy materials from sustainable sources, this study undertook the synthesis of energetic nitrostarches employing diverse sulfonitric mediums to better assess how they influence the characteristics and performance of potato starch nitrate. Accordingly, a deep exploration of the physicochemical properties, morphology, heat behavior, mechanical sensitivities, and combustion energy of starch nitrate was carried out. The experimental results highlighted that an increase in the nitric acid concentration from 70% to 100% enhanced the density (≥1.71 g/cm3) and the crystallinity of potato starch nitrate, whereas the nitrogen content does not exhibit any evident correlation. Moreover, its short-term stability remains unaffected as a function of nitric acid content, in contrast to the long-term stability together with mechanical sensitivities (Impact Sensitivity ≥ 4 J; Friction Sensitivity ≥ 252 N) that decrease with nitrogen content. The investigation of the thermolysis kinetics of starch nitrate demonstrated a decrease in the activation barrier (Ea) with the increase in nitrogen content. The Ea of high nitrogen content potato starch nitrate is inferior to that of cellulose nitrate, proving the enhanced reactivity of starch nitrate. These findings demonstrated that the elaborated nitrogen-rich potato starch biopolymers display promising features that support their use in high-performance propellant or explosive formulations.

Effects of Al content and particle size on the combustion characteristic of hydrogen peroxide gel and micron-aluminum mixtures

As a novel green and high-performance propellants, H2O2/H2O/Al propellants have the potential to solve the pollution problem faced by composite solid propellants while maintaining high performance. However, the drawback that it cannot be ignited at a low oxidizer-to-fuel weight ratio (O/F) and a low pressure hinders its further development. Fortunately, this ignition defect was addressed by the mixture of hydrogen peroxide gel and micron-Al in our recent work. In this paper, the effects of Al content and particle size on the combustion characteristic of burning surface propagation and combustion products of the mixture were investigated. Combustion experiments were conducted in a windowed pressure vessel, using mixtures with three mixing ratios (fuel-lean, stoichiometric, and fuel-rich) and Al particle diameters between 1 and 12 μm. The burning surface propagation was captured by a high-speed camera. The particle size distribution, component, and morphology of combustion products were characterized by laser particle size analyzer, X-ray powder diffraction, and scanning electron microscopy, respectively. And it is the first time that the combustion properties of H2O2/H2O/Al propellants (including H2O/Al propellants) are studied from the prospective of particle size distribution of combustion products. Results showed that with the decrease of Al content and the increase of particle diameter, the combustion intensity of the mixture decreased, resulting in the agglomeration of melted Al droplets on the burning surface. When the Al content was decreased to O/F = 1.7, Al particles in the mixture were no longer further oxidized in the process of combustion. When the Al particle diameter was increased to 7–10 μm, burning rates of the mixture at O/F = 1.7–1.1 tended to be stable. The combustion of mixtures containing 3–7 μm was kinetically controlled. From the prospective of variable burning rate and efficient combustion, the appropriate Al content in the mixture was O/F = 1.7–1.1, and the Al particle diameter should be kept within 1–7 μm.

Unraveling the Effect of MgAl/CuO Nanothermite on the Characteristics and Thermo-Catalytic Decomposition of Nanoenergetic Formulation Based on Nanostructured Nitrocellulose and Hydrazinium Nitro-Triazolone

The present study aims to develop new energetic composites containing nanostructured nitrocellulose (NNC) or nitrated cellulose (NC), hydrazinium nitro triazolone (HNTO), and MgAl-CuO nanothermite. The prepared energetic formulations (NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO) were analyzed using various analytical techniques, such as Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA), and differential scanning calorimetry (DSC). The outstanding catalytic impact of MgAl-CuO on the thermal behavior of the developed energetic composites was elucidated by kinetic modeling, applied to the DSC data using isoconversional kinetic methods, for which a considerable drop in the activation energy was acquired for the prepared formulations, highlighting the catalytic influence of the introduced MgAl-CuO nanothermite. Overall, the obtained findings demonstrated that the newly elaborated NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO composites could serve as promising candidates for application in the next generation of composite explosives and high-performance propellants.

Nitrostarch as a promising insensitive energetic biopolymer: Synthesis, characterization, and thermal decomposition kinetics

Natural polysaccharides have been outlined as one of the natural sources with more potential to obtain bio-energetic polymers through the chemical modification of their structure. In this work, nitrostarch, as an energetic nitrogen-rich polysaccharide, was successfully synthesized through the chemical modification of native potato starch . The synthesized energetic polymer and its precursor were extensively characterized using various analytical techniques and the obtained results confirm the functionalization process of the starch. In addition, its physicochemical features, molecular structure, morphology, and thermal behavior were determined using an electronic densimeter, elemental analysis, FTIR, SEM, TGA, and DSC . The sensitivity characteristics, the heat of combustion, and the heat of formation of the synthesized nitrostarch have been determined and its energetic performances were predicted using the EXPLO5 V6.04 software. Experimental results highlight promising features of the nitrostarch such as nitrogen content of 13 %, a density of 1.7365 g/cm 3 , and a detonation velocity of 7892 m/s in comparison to those of conventional nitrocellulose . In addition, the thermal decomposition kinetics of the nitrostarch have been deeply investigated as well using isoconversional kinetics analysis, and its Arrhenius parameters were derived for the first time. Finally, the obtained results demonstrated that this newly produced nitrogen-rich energetic material exhibits interesting energetic performance, which may further promote its application in explosives and high-performance propellants. In addition, this study will help to restore the forgotten interest concerning the employment of nitrostarch as a high-energy bio-polymer and to complete knowledge gaps and future trends for the industrial applications of this compound. • Nitrostarch was successfully prepared from native potato starch. • The properties of nitrostarch were compared to those of cellulose nitrate. • The synthesized nitrostarch revealed high nitrogen content, increased densities, good thermal stability, and outstanding insensitivity characteristics. • The thermal decomposition kinetics of nitrostarch has been deeply investigated and reported for the first time in the literature. • The calculated detonation parameters highlighted the interesting energetic performances of nitrostarch.

Study on the interfacial interaction between ammonium perchlorate and hydroxyl-terminated polybutadiene in solid propellants by molecular dynamics simulation

Abstract The interfacial interaction between the main oxidant filler ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) matrix in AP/HTPB propellants were studied via an all-atom molecular dynamics simulation. The results of the simulation showed the effects of the microscopic cross-linked structure of the matrix, stretching rate during uniaxial stretching, and contact area between the filler and matrix on the mechanical properties, such as the stress and strain of the composite solid propellant. Among the aforementioned factors, the stretching rate considerably affects the mechanical properties of the solid propellant, and the maximum stress of the solid propellant proportionally increases with the stretching rate. When defects were introduced on the surface of the AP filler, the contact area between the filler and matrix affected the strain type of the matrix molecules. Owing to the interaction between the molecules and atoms, the strain behaviour of the matrix molecule changed with the change in its microscopic cross-linked structure during uniaxial stretching. Molecular dynamics simulations were used to explore the characteristics at the AP–HTPB interface in AP/HTPB propellants. The aforementioned simulation results further revealed the interfacial interaction mechanism of the AP–HTPB matrix and provided a theoretical basis for the design of high-performance propellants.

Structure and property of propellant based on nitroglycerine/glycerol triacetate mixed plasticizers: molecular dynamics simulation and experimental study.

Molecular dynamics simulation has been used to investigate the influence of nitroglycerine (NG)/glycerol triacetate (GTA) mixed plasticizers on the plasticizing ability of nitrocellulose (NC) binder in solid propellant. The radial distribution function and binding energy indicated that NC/plasticizers blends showed stronger intermolecular interaction of van der Waals and hydrogen bonds. The mean-squared displacements of plasticizers and volume distribution revealed that the mobility of plasticizer GTA in the NC polymer binder was higher than that of NG. Then, the mechanical properties of the propellant based on NG/GTA mixed plasticizers were investigated systematically using experimental and simulation calculation method. The results suggested that the ductility of propellant based on NG/GTA mixed plasticizers was improved, implying that NG/GTA mixed plasticizers have a higher plasticizing efficiency for NC. Furthermore, we conducted experimental studies on the effects of NG/GTA mixed plasticizers on the energy and combustion properties of propellants. It was shown that NG/GTA mixed plasticizers could enhance the combustion efficiency of propellants effectively at low pressures. These computational and experimental studies provided guidance for the application of NG/GTA mixed plasticizers in high-performance propellants.

Effect of hexanitroethane (HNE) and hydrazinium nitroformate (HNF) on energy characteristics of composite solid propellants

This work deals with energy performance calculate results of new solid composite propellants based on Hexanitroethane (HNE) and Hydrazinium nitroformate (HNF). The energy characteristics of solid propellants with HNE and HNF are estimated using NASA Chemical Equilibrium with Applications (CEA). The effect of HNE and HNF as energetic oxidizers on the energy characteristics of composite modified double-base (CMDB) propellants, hydroxyl-terminated polybutadiene (HTPB) propellants, nitrate ester plasticized polyether (NEPE) propellants, glycidyl azide polymer (GAP) propellants has been carried out. Characteristics of ingredients and propellant formulations with HNE and HNF are presented together with the calculate results which demonstrate the increased performance compared to conventional high-performance propellants based on Ammonium Perchlorate (AP). The results show that HNE and HNF can improve the standard theoretical specific impulse of the four propellants in different degrees, and HTPB propellant has the most significant improvement, which is 12.26 s for HNE-based propellant and 14.12 s for HNF-based propellant. At the same time, both HNE and HNF reduce the infrared emission of propellant exhaust plumes when they replace AP, and reduce or even completely eliminate HCl gas in exhaust products. Therefore, it is expected that HNE-based and HNF-based propellants may provide a promising chlorine-free alternative to existing AP-based formulations.

Synthesis and characterization of new insensitive and high-energy dense cellulosic biopolymers

In the present study, microcrystalline cellulose carbamate nitrate (MCCCN) and ordinary cellulose carbamate nitrate (OCCN) as a new class of insensitive and high-energy dense polymers were successfully synthesized for the first time through a simple efficient procedure. Carbamate-functionalized cellulose and cellulose microcrystals (OCC and MCCC) were firstly prepared from their precursors using chlorosulfonyl isocyanate (CSI) as carbamate agent. After that, the nitration of functionalized and non-functionalized cellulosic precursors with concentrated sulfonitric mixtures was undertaken. Their physico-chemical features, molecular structure, thermal behavior, and mechanical sensitivity features were determined, and compared to those of the common nitrocellulose and emergent microcrystalline cellulose nitrate (OCN and MCCN). Furthermore, the detonation properties of the developed energetic polymers were evaluated using Explo5 (V6.04) computer code. The findings of this study confirm the efficiency of the performed surface modification approach to produce insensitive MCCCN and OCCN with excellent features such as density of 1.687 g/cm3 and 1.703 g/cm3, explosion energy of 5040 kJ/kg and 5334 kJ/kg, and detonation velocity of 7613 m/s and 7785 m/s, respectively, which are better than those of the conventional nitrocellulose. This work provides a novel and sustainable pathway to prepare new insensitive energetic polymers with outstanding physicochemical properties and energetic performances from renewable cellulose, which may further promote the functional application of cellulose and open the way of cellulose-based energetic materials for explosive formulations and high-performance propellants.

New insensitive nitrogen-rich energetic polymers based on amino-functionalized cellulose and microcrystalline cellulose: Synthesis and characterization

In this work, pristine cellulose amine nitrate (OCAN) and microcrystalline cellulose amine nitrate (MCCAN) as a new class of insensitive energetic nitrogen-rich polymers were successfully synthesized for the first time through chemical modification of pristine cellulose (OC) and microcrystalline cellulose (MCC). The synthesized energetic polymers and their precursors were deeply characterized using various analytical methods. Moreover, the energetic performances of the prepared nitrated polymers was predicted using the EXPLO5 V6.04 code. Their heats of combustion and mechanical sensitivities against impact and friction were also evaluated. Experimental results confirm the effectiveness of the functionalization process to synthesize OCAN and MCCAN with interesting features such as nitrogen content of 18.42% and 20.06%, density of 1.719 g/cm3 and 1.727 g/cm3, and detonation velocity of 7576 m/s and 7905 m/s, respectively, which are significantly better than those of the conventional nitrocellulose. In addition, the proposed approach allows the production of thermally stable energetic biopolymers with improved sensitivity characteristics. Thus, this investigation provides a novel and sustainable methodology to obtain a new class of insensitive energetic nitrogen-rich polymers based on cellulose, which may further promote their applications in explosives and high-performance propellants.

Podcast: When rocket chemistry blasted off and came back to Earth

Rocket propellant research had its heyday in the mid-20th century, when the space race and the Cold War meant chemists had plenty of money and long leashes. Only a few of their most interesting ideas ended up in working rockets, but they charted new areas of chemical space, some of which, like boron chemistry, have proved useful in other fields. Geopolitical shifts, along with a growing emphasis on health, safety, and the environment, put a damper on propellant chemistry in the last decades of the 1900s. But the need for high-performance propellants hasn’t gone away, and neither has chemists’ interest in pushing the envelope. In this episode of Stereo Chemistry, we hear from chemists who lived through the heady days of the ’50s and ’60s and the ones carrying rocket chemistry’s torch today. Listen at cenm.ag/rocketfuel.

High-performance Propeller Optimization Design

High-performance Propeller Optimization Design

New directions in the area of modern energetic polymers: An overview

Energetic polymers containing nitro, nitrato, and azido groups release high energy during combustion and thereby increase the performance of the systems. A number of energetic polymers have been found suitable for use as binders in high-performance propellant and explosive formulations. This review describes the synthetic and application aspects of various modern energetic polymers for explosive formulations and propellants.

Mechanical response and failure of High Performance Propellant (HPP) subject to uniaxial tension

As part of a program to characterize and understand the mechanical response and failure behavior of the High Performance Propellant (HPP), uniaxial tensile tests were conducted. The mechanical properties of the HPP solid propellant subject to tension are investigated as a function of both the loading (strain) rate and the temperature. The nominal strain rate varies from 10−6 to 10−2 s−1 and the temperature varies from −50 to 50 °C. Digital image correlation (DIC) technique was used to obtain the full field deformation measurement over the sample surface, from which both the axial strain and the circumferential strain were determined, and as a result, volume changes during the uniaxial tension were studied. Some of the material parameters, e.g., Young’s modulus E, the tensile strength σ max, and uniaxial tensile strain at the maximum tensile stress ϵ max, were found to be extremely sensitive to both the strain rate and the temperature. It was also observed that during the linear portion of the uniaxial tension, the HPP is close to incompressible. But when deformation enters the nonlinear regime, volume change of the sample accelerates and such a significant volume increase during the nonlinear portion of the deformation can be attributed to the formation and extension of damage within the gage section, which lead to the macroscopic tearing failure of the material.

ChemInform Abstract: Ionic Liquid Propellants: Future Fuels for Space Propulsion

AbstractReview: 31 refs.

Ionic Liquid Propellants: Future Fuels for Space Propulsion

Use of green propellants is a trend for future space propulsion. Hypergolic ionic liquid propellants, which are environmentally-benign while exhibiting energetic performances comparable to hydrazine, have shown great potential to meet the requirements of developing nontoxic high-performance propellant formulations for space propulsion applications. This Concept article presents a review of recent advances in the field of ionic liquid propellants.

High Performance Propeller System for a Multi-Mission Micro Aerial Vehicle

The new concept of a multi-mission micro air vehicle (MMMAV) was designed in order to enhance the efficiency, endurance and performance of this small vehicle which must be able to perform several capabilities: vertical take-off and landing (VTOL), hovering, low speed translation and high forward speed flight. The key factor of achievement is the propulsion system. Firstly, to ensure the capacity of the new propeller system concept, a high performance propeller system was designed and studied. Two testing conditions were investigated: hovering and a forward flight at a desired maximum speed. Initially, an analytical approach was adopted with preliminary calculations using XROTOR and CROTOR code to determine the 10 best propellers with optimal efficiency. Then, an experiment of both static and dynamic thrust was conducted. The rotation speed, thrust, torque, electric tension and current were carefully measured and compared with measurements taken for the in-line ‘APC-7×5’ propellers which are used by other MMMAVs. The results showed the new coaxial propeller system was highly efficient when combined with the ‘GWS9×4.7 Slow’ and the ‘APC6×4’ propellers. The power required was reduced by approximately 20% and 30% for hovering and forward flight, respectively.

Mastering Cryogenic Propellants

AbstractThe National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) began experimentation with cryogenic propellants in the early 1950s to understand the potential of these high-performance propellants for use in liquid propellant rocket engines. Supporting these tests required learning how to both design cryogenic systems and develop procedures to safely and reliably work with cryogenic fuels and oxidizers. This early work led to the development of a skill set that has been core to the center ever since. When NASA was formed and the exploration missions were defined, it became clear that the ability to use cryogenic propellants in the thermal and microgravity environment of space was critical to mission success, and the agency was tasked with enabling this capability. To support development of the Centaur upper stage and the Saturn S-IVB stage, GRC researchers and engineers initiated extensive technology development for the in-space application of cryogenic fluid management (CFM)...

Design of an Autonomous Hover Control System for a Small Quadrotor

This paper discusses the development of the control system of a mini quadrotor in Konkuk University for indoor applications. The attitude control system consists of a stability augmentation system, which acts as the inner loop control, and a modern control approach based on modeling will be implemented as the outer loop. The inner loop control was experimentally satisfied by a proportional-derivative controller; this was used to support the flight test in order to validate the modeling. This paper introduces the mathematical model for the simulation and design of the optimal control on the outer loop control. To perform the experimental tests, basic electronic hardware was developed using simple configurations; a microcontroller used as the embedded controller, a low-cost 100 Hz inertial sensors used for the inertial sensing, infra-red sensors were employed for horizontal ranging, an ultrasonic sensor was used for ground ranging and a high performance propeller system built on an quadrotor airframe was also employed. The results acquired from this compilation of hardware produced an automatic hovering ability of the system with ground control system support for the monitoring and fail-safe system.

Burning Characteristics of Polytetrahydrofuran-Based Composite Propellant

D EVELOPMENT of a wide variety of rockets has required development of propellants having a wide range of performance corresponding to the purposes for which they are used. Especially, a high burning rate propellant is neededwhen developing a high performance rocket motor. The use of burning rate modifiers, metal fuels, and high energetic materials is a typical method to obtain a high burning rate propellant. Recently, nanosized metal fuels [1–4] and high energetic materials [5,6] have been developed, and researchers have been investigating the burning characteristics of solid propellants using them [1–13]. Glycidyl azide polymer is a typical energetic binder characterized by the N3 chemical bond [5,6,9–11]. The burning characteristics of the glycidyl azide polymer-based propellant are superior to those of common propellants, such as the hydroxyl-terminated polybutadiene (HTPB)based propellant. However, it is presently difficult tomake a practical solid propellant using high energetic binders and nanosized metal fuels because these materials are expensive and cannot be massproduced. It is necessary to find an inexpensive material to obtain a high performance propellant. Another approach is the application of new nonenergetic materials as the propellant fuel-binder. For example, hydrogenated hydroxylterminated polyisoprene [14], polymethylmethacrylate [15], polyethylene [16,17], polyvinyl chloride [18,19], polycaprolactone [20], etc., are now being evaluated. The burning performances of propellants using these polymers are not inferior to those of the HTPB-based propellant. Polytetrahydrofuran (PTHF) is used as an ingredient for rubber products and is produced in several different molecular weights. This polymer is mass-produced commercially and inexpensive. The chemical properties of PTHF are shown in Table 1. The repeating unit of PTHF consists of a single bond and has one oxygen atom, four carbon atoms, and eight hydrogen atoms. PTHF has a hydroxide group on one side of the molecular chain of PTHF and a hydrogen atom on the other side. The molecular structure of PTHF is similar to that of HTPB. PTHF is not an energetic binder. However, it could be expected that the burning performance of a solid propellant could be improved by using PTHF as a binder, comparedwithHTPB, because the amount of oxygen atom per mole of PTHF is greater than that of HTPB. In this study, the burning rate characteristics of the PTHF-based composite propellant were investigated and compared with the characteristics of the HTPB-based composite propellant. According to the results, it was found that the performance of the PTHF-based composite propellant is superior to that of the HTPB-based propellant.