Potential Use of CL‐20 in TNT/ETPE‐Based Melt Cast Formulations

An attempt was made to introduce CL‐20 in a TNT/energetic thermoplastic elastomer (ETPE)‐based melt cast formulation, to obtain an insensitive composition with reduced adverse environmental properties. A loading limit of 42% w/w of CL‐20 in melted TNT was observed, while it should have been around 70%. This paper describes the investigation that was undertaken to understand the observed phenomena. It was demonstrated that CL‐20 undergoes structural alterations in melted TNT. The relative solubility of CL‐20, RDX and HMX in melted TNT was determined and the α‐, β‐, γ‐ and ε‐CL‐20 were prepared and characterized using Raman spectroscopy and DTA. CL‐20 was mixed in melted TNT, as much as 4.2 g of CL‐20 dissolved in 100 g of TNT. This allowed a transformation from ε to β‐CL‐20 and a modification of CL‐20 particle size and distribution. The later modification induced a raise in CL‐20 specific surface and was responsible for the loading limit, while the transformation to β‐CL‐20 caused an increase in sensitivity and a decrease in density. This indicates that the use of CL‐20 in TNT melt cast is not promising. Our study also showed that CL‐20 is sensitive to morphological transformations, which should be taken into consideration in future processing using this compound.     

Structural and Preliminary Explosive Property Characterizations of New 3,4,5‐Triamino‐1,2,4‐triazolium (Guanazinium) Salts

Two new highly stable energetic salts were synthesized in reasonable yield by using the high nitrogen‐content heterocycle 3,4,5‐triamino‐1,2,4‐triazole and resulting in its picrate and azotetrazolate salts. 3,4,5‐Triamino‐1,2,4‐triazolium picrate (1) and bis(3,4,5‐triamino‐1,2,4‐triazolium) 5,5′‐azotetrazolate (2) were characterized analytically and spectroscopically. X‐ray diffraction studies revealed that protonation takes place on the nitrogen N1 (crystallographically labelled as N2). The sensitivity of the compounds to shock and friction was also determined by standard BAM tests revealing a low sensitivity for both. B3LYP/6–31G(d, p) density functional (DFT) calculations were carried out to determine the enthalpy of combustion (Δ_cH (1) =−3737.8 kJ mol⁻¹, Δ_cH (2) =−4577.8 kJ mol⁻¹) and the standard enthalpy of formation (Δ_fH° (1) =−498.3 kJ mol⁻¹, (Δ_fH° (2) =+524.2 kJ mol⁻¹). The detonation pressures (P (1) =189×10⁸ Pa, P (2) =199×10⁸ Pa) and detonation velocities (D (1) =7015 m s⁻¹, D (2) =7683 m s⁻¹) were calculated using the program EXPLO5.     

A Novel Insensitive High Explosive 3,4‐Bis (Aminofurazano) Furoxan

A novel insensitive high explosive 3,4‐bis (aminofurazano) furoxan (BAFF) was prepared using 3‐amino‐4‐acylchloroximinofurazan (ACOF) as a precursor. The molecular and crystal structures of BAFF were characterized by IR, MS, ¹H NMR, ¹³C NMR, elemental analysis, and single crystal X‐ray diffraction. The single crystal structure of BAFF recrystallized from water is monoclinic, space group P 21/c, and ρ_c=1.745 g cm⁻³, and that recrystallized from ethanol is triclinic, space group P 1, and ρ_c=1.737 g cm⁻³. BAFF has multiple crystal forms. The calculated detonation velocity by BKW code is 8100 m s⁻¹ (ρ=1.795 g cm⁻³, theoretical density calculated by quantum chemistry) and the experimental value is 7177 m s⁻¹ (ρ=1.530 g cm⁻³, charge density). The tested values of impact, friction, and electrostatic spark sensitivity show that BAFF is insensitive.     

Studies of Novel Heterocyclic Insensitive High Explosive Compounds: Pyridines,Pyrimidines, Pyrazines and Their Bicyclic Analogues

The rationale behind using heterocyclic compounds [1], particularly nitrogen heterocycles, as higher energy insensitive high explosives is discussed, including the potential advantages compared with carbocyclic compounds. The types of functional groups used to impart energy to heterocyclic nuclei, whilst maintaining insensitivity, and methodologies for their introduction, are covered. The latter include nitration (by conventional and clean synthetic methods), amination, and oxidation (on ring heteroatoms and of exocyclic amino groups). Strategies for maximising the energetic content of a given heterocyclic nucleus are also examined. The syntheses of specific examples at QinetiQ are described, based on the following nuclei: pyridine, pyrimidine, pyrazine, quinoxaline, quinazoline, pteridine and purine. Strategies for obtaining the desired amino‐nitro derivatives and their heterocyclic N‐oxides are outlined. Optimisation of the synthetic routes for several candidates is discussed. The physical, explosive and thermal properties of the more successful candidates are described, with suggestions for their potential application in military stores.     

Insensitive High Explosives II: 3,3′‐Diamino‐4,4′‐azoxyfurazan (DAAF)

This paper reviews the synthesis, properties, performance, and safety of the insensitive explosive 3,3′‐diamino‐4,4′‐azoxyfurazan (DAAF, C₄H₄N₈O₃), CAS‐No. [78644‐89‐0], and 18 formulations based on it. Though having a moderate crystal density only, DAAF offers high positive heat of formation and hence superior performance when compared with TATB. It is friction and impact insensitive but is more sensitive to shock than TATB and has an exceptionally small critical diameter and performs very well at low temperatures unlike other insensitive explosives. 39 references to the public domain are given. For Part I see Ref. [1].     

Gels as Energy Dissipation Media for Energetic Materials Desensitization

The hypothesis that gels, which have a variety of dissipation mechanisms in response to external forces can provide efficient energy deflection media protecting sensitive energetic materials from accidental initiation is explored. Entrapment of explosives, with an emphasis on peroxide materials, in gels is demonstrated as a general method to substantially lower explosives sensitivity diverting stimuli from the sensitive materials to the gel. Friction is a more difficult stimulus to dissipate in comparison to impact. The desensitization method developed, is with minimal material manipulations. Practical considerations as mode of application, solubility, and controlling speed of gelation determine that the method of choice is a sol‐gel process using a mixture of three alkylalkoxysilanes, R_nSi(OR′)_4–n, producing a hybrid organic‐inorganic gel enabling complete triacetone triperoxide (TATP) desensitization at 20–25 % v/v concentrations.     

Hydrostatic Compression Curve for Triamino‐Trinitrobenzene Determined to 13.0 GPa with Powder X‐Ray Diffraction

Using powder X‐ray diffraction in conjunction with a diamond anvil cell (DAC), the unit cell volume of triamino‐trinitrobenzene (TATB) has been measured from ambient pressure to 13 GPa. The resultant isotherm is compared with previous theoretical (Byrd and Rice and Pastine and Bernecker) and experimental (Olinger and Cady) works. While all reports are consistent to approximately 2 GPa, our measurements reveal a slightly stiffer TATB material than reported by Olinger and Cady and an intermediate compressibility compared with the isotherms predicted by the two theoretical works. Analysis of the room temperature isotherm using the semi‐empirical, Murnaghan, Birch–Murnaghan, and Vinet equations of state (EOS) provided a determination of the isothermal bulk modulus (K_o) and its pressure‐derivative (K_o′) for TATB. From these fits to our P–V isotherm, from ambient pressure to 8 GPa, the average results for the zero‐pressure bulk modulus and its pressure derivative were found to be 14.7 GPa and 10.1, respectively. For comparison to shock experiments on pressed TATB powder and its plastic‐bonded formulation PBX 9502 (95% TATB, 5% Kel‐F 800), the isotherm was transformed to the pseudo‐velocity U_s–u_p plane using the Rankine–Hugoniot jump conditions. This analysis provides an extrapolated bulk sound speed, c_o=1.70 km s⁻¹, for TATB and its agreement with a previous determination (c_o=1.43 km s⁻¹) is discussed. Furthermore, our P–V and corresponding U_s–u_p curves reveal a subtle cusp at approximately 8 GPa. This cusp is discussed in relation to similar observations made for the aromatic hydrocarbons anthracene, benzene and toluene, graphite, and trinitrotoluene (TNT).     

An Examination of Binder Systems and Their Influences on Burn Rates of High‐Nitrogen Containing Formulations

The examination of Laminac 4116/Lupersol and Epon 813/Versamid 140 binder systems, and their influences on burn rates of pyrotechnic formulations is described. Laminac 4116/Lupersol‐based formulations had shorter burn times and larger heat of explosion values compared to their Epon 813/Versamid 140 counterparts. An understanding of the chemical structures and approximate oxygen balances of these binder systems served to explain their burn time differences when used in pyrotechnic formulations. Bomb calorimetry of Laminac 4116/Lupersol‐ and Epon 813/Versamid 140‐based formulations provided heat of explosion values to further explain the burn time differences of the two binder systems used.     

Applications of High‐Nitrogen Energetics in Pyrotechnics: Development of Perchlorate‐Free Red Star M126A1 Hand‐Held Signal Formulations with Superior Luminous Intensities and Burn Times

Perchlorate‐free hand‐held signal illuminant formulations for the M126A1 red star parachute have been developed. The formulations exhibited longer burn times and higher luminous intensities compared to the US Army in‐service M126A1 formulation. The perchlorate‐free formulations derive their enhanced performance from the inclusion of strontium bis‐(1‐methyl‐5‐nitriminotetrazolate) monohydrate, the choice of magnesium used, and replacing a polyester binder system with an epoxy binder system.     

静态与动态高压对含能材料热分解的影响

利用常压和高压差示扫描量热仪（DSC、PDSC）在动态和静态状下研究了CL-20、HMX、RDX、NC、NG、NG NC等几种含能材料的热分解,探讨了常压与高压条件下,静态与动态对这些含能材料热分解的影响。结果显示含能材料热分解受压力和动态气氛的影响有三种情况：1、热分解同时受到压力和动态气氛的影响;2、热分解既不受压力也不受动态气氛的影响;3、热分解只受压力的影响而不受动态气氛的影响。     

New Method for Prediction of the Gurney Energy of High Explosives

An empirical new correlation is used to calculate the Gurney velocity as an important parameter for the estimation of explosive energy output without considering the heat contents of explosives and detonation products. The number of nitrogen molecules as well as the ratios of oxygen to carbon and hydrogen to oxygen are the fundamental factors in the new method. The new correlation may be applied to any C_aH_bN_cO_d explosive, in which b is nonzero, at any loading density. The calculated Gurney velocity for both pure and explosive formulations shows good agreement with respect to measured values. Moreover, there is no need to use any assumed decomposition reaction.     

New High‐Nitrogen Materials Based on Nitroguanyl‐Tetrazines: Explosive Properties,Thermal Decomposition and Combustion Studies

This paper describes the explosive sensitivity and performance properties of two novel high‐nitrogen materials, 3,6‐bis‐nitroguanyl‐1,2,4,5‐tetrazine ( 1 , (NQ₂Tz)) and its corresponding bis‐triaminoguanidinium salt ( 2 , (TAG)₂(NQ)₂Tz)). These materials exhibit very low pressure dependence in burning rate. Flash pyrolysis/FTIR spectroscopy was performed, and insight into this interesting burning behavior was obtained. Our studies indicate that 1 and 2 exhibit highly promising energetic materials properties.     

A Flow Time Model for Melt‐Cast Insensitive Explosive Process

Diphasic flows of concentrated suspensions of melt‐cast insensitive explosives exhibit specific rheological properties. In order to limit the handling of pyrotechnical products presenting a risk with respect to the mechanical and thermal shocks, a lot of work has been undertaken for many years in the civil engineering sector. The objective of this study is to propose a predictive model of the flow time of a concentrated suspension through a nozzle located at the bottom of a tank. Similar to our industrial process, the suspension is made out of insensitive energetic materials and flows under gravity. Experimental results are compared to three models (Quemada, Krieger‐Dougherty, and Mooney) predicting the viscosity μ of a suspension as a function of the solid volume fraction ϕ, the maximum packing density ϕ_m and the viscosity μ₀ of the interstitial liquid. De Larrard's model is used to calculate ϕ_m. The value of viscosity measured for the pure liquid is close to the one predicted by the Bernoulli theorem, where liquids are considered as incompressible and inviscid. Finally, it was found that the Quemada's model gives a fair agreement between predictions and experiments.     

环氧高温固化剂TTOA的合成与性能研究

采用熔融酯化法制备了环氧高温固化剂TTOA,通过凝胶点、耐热性、凝胶时间、溶解性、表观黏度等研究表明,原料配比是合成反应的关键所在,反应时间能够作为反应终点的控制因素。探讨了各种常用溶剂对TTOA的溶解性以及储存时间对TTOA/环氧体系凝胶时间和表观黏度的影响。实验表明:合成反应的表观活化能为42.44 kJ/mol;合成TTOA的最佳工艺为:反应温度(155±5)℃,反应时间0.5 h,THEIC与TOA的摩尔比0.5:1。此条件下的TTOA/环氧产物耐热温度达到了169.29℃。制得的TTOA/E44胶液具有良好的溶剂溶解性和室温储存稳定性,TTOA能够用作高性能潜伏型环氧固化剂。     

A New Computer Code for Prediction of Enthalpy of Fusion and Melting Point of Energetic Materials

The prediction of phase change properties of energetic materials is important for the assessment of hazardous energetic materials. A novel user‐friendly computer code, written in Visual Basic, is introduced to predict the melting point and the enthalpy of fusion of energetic materials by only using their molecular structure parameters. It can be used for different types of energetic compounds including polynitro arenes, polynitro heteroarenes, acyclic and cyclic nitramines, nitrate esters, and nitroaliphatic. The predicted results were compared with several of the best available methods, which confirmed the higher reliability of the new computer code for some new and well‐known energetic compounds with complex molecular structures. This code can be used for designing of energetic compounds with desirable phase change properties.     

A New Computer Code for Assessment of Energetic Materials with Crystal density,Condensed Phase Enthalpy of Formation,and Activation Energy of Thermolysis

Crystal density and enthalpy of formation of the condensed phase of energetic compounds are two important input parameters for the performance prediction in several computer codes for rapid hazard assessment of energetic materials. A novel easy‐to‐handle user‐friendly computer code in Visual Basic is introduced to predict these parameters for various energetic compounds including nitroaliphatics, nitrate esters, nitramines, polynitroarenes, and polynitroheteroarenes. The calculated values can be used as inputs for other thermochemical/hydrodynamic computer codes. This computer code is also able to calculate the activation energies of thermal decomposition of polynitroarenes and nitramines in condensed state. The number of carbon, hydrogen, oxygen, and nitrogen atoms and specification of some molecular fragments are input parameters for this code without using any experimental data. The new algorithms on the base of easy‐to‐get input parameters are tested for some new energetic compounds, which provide more reliable results as compared to the best available methods.     

Preparations and Properties of Porous Copper Materials for Lithium-Ion Battery Applications

Because of its special porous structure and novel physical and mechanical properties, porous copper is widely studied in many fields, especially in high-performance lithium-ion batteries. It is quite necessary for researchers to understand the recent progress of porous copper. Herein, we review the preparations, properties, and lithium-ion battery (LIB) applications of porous copper. Its main research direction and development trend are also pointed.     

High Energy Propellants for Advanced Gun Ammunition Based on RDX,GAP and TAGN Compositions

A number of gun propellant compositions based on RDX, GAP, TAGN and combinations thereof were formulated and studied with the aim to select the suitable composition for advanced gun ammunition in respect of processability and ballistic performance. Theoretical thermochemical properties of the compositions were computed using a ‘THERM’ programme and the ballistic performance was evaluated on the basis of closed vessel tests. In addition, sensitivity, thermal characterization, thermal stability and mechanical properties of the compositions were also determined for assessing the suitability for application. A composition containing 28% NC, 45% RDX, 20% TAGN, 6% GAP, 0.7% carbamite and 0.3% resorcinol was found to provide higher level of force constant at relatively lower flame temperature, reasonably good burning rate characteristics and mechanical properties.     

Synthesis and Photopolymerizations of New Crosslinkers for Dental Applications

Summary: Five new crosslinkers for use in dental composites were synthesized. Four are based on TBHMA: 1 via reaction of TBBr and Bisphenol A; 2 by hydrolysis of t‐butyl groups of the first monomer to give a diacid derivative; 3 by conversion of the first monomer to an amide derivative using benzyl amine; 4 by conversion of the first monomer to amide derivative using APTES. The AHM‐based monomer 5 was synthesized from the Michael addition of APTES to AHM. The photopolymerization behaviors of the synthesized monomers with Bis‐GMA, TEGDMA and HEMA were investigated using photodifferential scanning calorimetry at 40 °C using DMPA as photoinitiator. The polymerization rates and degrees of conversion for mixtures of any of the monomers 1 – 4 with Bis‐GMA:TEGDMA were found to be similar to Bis‐GMA:TEGDMA, higher than Bis‐GMA:HEMA, and also higher than mixtures with Bis‐GMA:HEMA. The incorporation of TBHMA‐based monomers into the conventional resin mixture (Bis‐GMA and TEGDMA) reduced the polymerization shrinkages. Monomer 5 and its mixtures polymerized much faster and to higher degrees of conversion than the other investigated systems, however, this system exhibited the largest volume shrinkage.

Structures of some of the new crosslinkers synthesized.     

Maleated High Density Polyethylene Compatibilized High Density Polyethylene/Hydroxyapatite Composites for Biomedical Applications: Properties and Characterization

The study investigated the use of maleated high density polyethylene (mHDPE) as a compatibilizer in high density polyethylene/hydroxyapatite (HDPE/HA) composites for biomedical applications. The addition of HA increased the strength and stiffness of HDPE/HA composites while the use of mHDPE in HDPE/HA composites improved its elongation at break values. The SEM images revealed that the addition of mHDPE has induced the formation of HDPE fibrils in mHDPE/HA composites. The size of apatite layer increased with simulated body fluid (SBF) immersion time and the formation of apatite layers on the surface of composites indicates excellent biocompatibility properties.