Polyurethane elastomers were considered as an ideal material for flexible devices. However, the application of polyurethane elastomers was still largely limited by the disadvantages of poor self-healing property and low conductivity. In this work, a self-healing polyurethane with adjustable mechanical performances was constructed via the introduction of reversible dynamic interactions in the polyurethane matrix, such as metal ion-tripyridine coordinations, disulfide bonds and hydrogen bonds. And lithium salt was incorporated into the polyurethane to achieve ionic conductivity. The obtained polyurethane exhibited adjustable breaking strength with a range of 0.77 - 10.75 MPa, breaking elongation in the range of 1719 - 1863 %, and conductivity in the range of 0.08 1.57 x 10-3 S/m by adding different LiTFSI (5 - 35 wt%) into the polyurethane. In addition, the polyurethane displayed efficient self-healing behavior, well fatigue resistance, and recyclability. Also, the polyurethane showed great application prospects as flexible sensors by performing stable and sensitive responses to a wide range of human body movements.

In this research, an ammonium perchlorate/polydopamine (AP/PDA) core–shell composite was prepared in a non-aqueous solution to reduce the mechanical sensitivity of ammonium perchlorate (AP). The result showed that the AP/PDA core–shell composite could be successfully constructed in ethyl acetate solution with an AP recovery rate that reached 86%. The mechanical sensitivity of the obtained AP/PDA core–shell composite was significantly reduced with a PDA content of only 0.76%. The DSC and TG also indicated that the coating of PDA showed catalytic activity in the thermal decomposition of AP with a lower decomposition temperature and a decreased Ea value of AP. Thus, this study proposed a simple strategy for achieving a good balanced between harnessing the energy and ensuring the safety of ammonium perchlorate by significantly reducing its mechanical sensitivity by using a very low polydopamine coating layer content, and this shows great potential for the design and fabrication of insensitive energetic composites for use in propellants.

分层强夯替换方法中,下层采取柱锤强夯替换,并建立较长的替换墩来穿过软弱土质.顶层回填土层采取平锤强夯替换,使松散回填土实现完整的挤密夯实.大面积地基施工监控结果和油罐充水预压测试结果显示,油罐地面的承载能力和变形程度均可达到有关标准要求,而分层强夯置换技术在该项目中有较好的地面强化效应,可在同类施工中推广应用.

Transition metal borides have great potential to be low-cost, high-performance catalysts for novel energies despite the synthesis is rather difficult. In this paper, the reduced gra-phene oxide (rGO) supported iron boride (Fe2B/rGO) based catalysts are synthesized by a facile reduction method. The successful synthesis of Fe2B is confirmed by X-ray diffraction, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photo-electron spectroscopy (XPS) and other tests. HRTEM tests showed that the constructed Fe2B was embedded in the rGO, where B played the role of coordination atoms which could regulate the electronic structure of the catalysts and improve the catalytic performance towards oxygen reduction reaction (ORR). The electrochemistry tests showed that the peak current intensity of the Fe2B/rGO catalyzed ORR could be reached up to 7.6 mA/cm2, which surpassed that of the Pt/C (20 wt%) catalyst. The current intensity can be kept at 82.47% after continuous running 20,000 s, which is higher than the Pt/C catalyst (79.4%). The onset potential reaches up to 0.95 V, which is only 0.06 V lower than that of Pt/C (20 wt%) catalyst. Both RDE and RRDE tests confirmed that the Fe2B/rGO catalyzed ORR major happed through 4-electron pathway. The redistributed electron between iron and boron atoms promoted the happening of ORR on Fe2B/rGO catalysts. The results of this work provide a novel way to develop high performance transition metal boride based catalysts for ORR.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Adhesive hydrogels have been considered as one of the most ideal materials for wound dressing. However, most existing adhesive hydrogels still have disadvantages such as low mechanical properties, poor biological activity (antibacterial and hemostatic ability), and low biocompatibility, which largely limit their application. Thus, it is highly desired to prepare a hydrogel-based wound dressing with good self-healing, ideal adhesive properties, rapid hemostasis, and excellent wound infection prevention activity. In this study, a simple method was presented to prepare a PAM-Lignin-CS-Laponite-SA hydrogel for wound dressing. The obtained hydrogel displayed excellent self-healing ability and repeatable adhesive performance, benefiting from the introduction of hydrogen bonding and electrostatic interactions inside the hydrogel network. In addition, the PAM-Lignin-CS-Laponite-SA hydrogel also exhibited low cell cytotoxicity, good antibacterial activity, and outstanding hemostatic properties. In conclusion, the PAM-Lignin-CS-Laponite-SA hydrogel demonstrated good tissue adhesion, excellent self-healing ability, effective bleeding control, and good antibacterial activity to prevent wound infection, which provides a new idea for developing a multifunctional hydrogel-based tissue adhesive hemostatic dressing.

Exploring new composite explosives based on 1,1-diamino-2,2-dinitroethylene (FOX-7) is significant in the field of insensitive high explosives (IHE). Despite having good detonation performance compared to RDX, FOX-7 has not been successfully applied in the preparations of aluminized explosives due to the poor explosion heat values. In this paper, the explosion heat and detonation velocity of FOX-7-based aluminized explosives were studied systematically. The experiment results showed that the explosion heat of FOX-7-based aluminized explosives are significantly lower than that of RDX-based ones, especially when the content of aluminum powder exceeds 30%. To solve this problem, a simple but effective method of adding RDX to FOX-7-based aluminized explosives was developed, leading to a huge growth of explosion heat values. Finally, in order to compare the safety performance with RDX-based aluminized explosives, the low vulnerability of the FOX-7/RDX-based aluminized explosives formulation was investigated by fast cook-off, sympathetic detonation and 12.7 mm bullet impact tests. The results showed that the safety performance of FOX-7/RDX-based aluminized explosives is better than that of RDX-based aluminized explosives, proving that good low vulnerability is kept with the addition of RDX into FOX-7-based aluminized explosives.

FOX-7是一种性能优异的不敏感单质炸药,也是今后在低易损弹药上推广应用的主要候选炸药之一.重点综述了国内外近年来报道的FOX-7在炸药中的应用及性能研究进展,包括FOX-7的合成制备、分子结构及晶型、表界面性能、热安定性能以及以FOX-7为基的炸药的机械感度、爆速、爆压、冲击波感度、小尺寸装药快速烤燃、慢速烤燃、子弹撞击试验等.其中,对FOX-7炸药不敏感性的评价方式主要是与相同状态的RDX基炸药和TNT炸药进行试验对比.指出FOX-7是一种具有应用价值的高能不敏感炸药,要实现FOX-7炸药在弹药中的应用,今后还要加强高品质、规模化、低成本FOX-7制备工艺技术研究以及FOX-7炸药在大尺寸战斗部中的装药技术研究.

To optimize the energy output and improve the energy utilization efficiency of an aluminized explosive, an explosion device was developed and used to investigate the detonation pressure and temperature of R1 (Al6) aluminum powder and the aluminum powder particle gradation of R2 (Al6+Al13), R3 (Al6+Al24) and R4 (Al6+Al flake) in a confined space. By using gas chromatography, quantitative analysis and calculations were carried out to analyze the gaseous detonation products. Finally, the reaction ratios of the aluminum powder and the explosion reaction equations were calculated. The results show that in a confined space, the quasi-static pressures and equilibrium temperature of the aluminum powder in air are higher than in vacuum. In vacuum, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R3>R4>R2 and R3>R4>R1>R2, respectively. In air, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R2>R4>R3 and R1>R4>R2>R3, respectively. R4 (Al6+Al flake) and R3 (Al6+Al24) have relatively higher temperatures after detonation, which shows that the particle gradation method can enhance the reaction energy output of aluminum during the initial reaction stage of the explosion and increase the reaction ratio by 10.6% and 8.0%, respectively. In air, the reaction ratio of Al6 aluminum powder can reach as high as 78.16%, and the reaction ratio is slightly reduced after particle gradation. Finally, the reaction equations of the explosives in vacuum and in air were calculated by quantitative analysis of the explosion products, which provides a powerful basis for the study of RDX-based explosive reactions.

利用慢速烤燃试验和冲击波感度试验研究了FOX-7与RDX不同混合比例对炸药响应特性的影响.试验表明:当FOX-7的混入量(质量分数)低于72％时,炸药在慢速烤燃试验中的响应剧烈程度表现为爆轰反应,其临界起爆压力接近6.62 GPa;当FOX-7的混入量(质量分数)等于72％时,炸药在慢速烤燃试验中的响应剧烈程度由爆轰降至爆燃,其临界起爆压力升至7.27 GPa;当配方中完全采用FOX-7时,炸药在慢速烤燃试验中的响应剧烈程度由爆燃降至燃烧,临界起爆压力升至8.24 GPa.造成上述试验结果的原因可能是压装炸药在成型过程中因颗粒的破碎、重排作用使FOX-7对RDX形成包覆,进而改善了RDX材料点火增长速度快的本质特点.

To estimate the deflagration to detonation transition (DDT) process of explosives composed of common components,three kinds of composite explosives,P1 (40 ％ TNT/60 ％ RDX),P2 (40 ％ DNTF/40 ％ HMX/10 ％ TATB/5 ％Al/5 ％additives) and P3 (25 ％DNTF/40 ％AP/30 ％Al/5 ％additives) were prepared by melting-casting technology,and explosive P4(30 ％RDX/30 ％ AP/30 ％ Al/10 ％additives)was prepared by casting technology.The DDT test for the four kinds of explosives were carried out by the coaxial ionization probe test technology,and the DDT response characteristics of four kinds of explosives were analyzed by the broken status of DDT tube,wave front propagation velocity in the DDT process and detonation transition distance.The results show that the DDT of explosives P1,P2 and P3 takes place and the detonation transition distance is 750-825 mm,375-450 mm and 675-750 mm,respectively,while the DDT of explosive P4 does not take place.For the brokenness of DDT tube,explosive P2 is the most violent,explosive P3 is second and explosive P1 is the smallest,indicating that the broken extent of DDT tube is positive correlation to the detonation pressure of explosive and if the formulation contains the ingredients that the thermal decomposition temperature is approaching,the thermal decomposition energy can be added quickly,and causes the combustion to be unstable,then increases DDT.The casting technology can decrease the possibility of DDT due to the presence of inert additives on the isolation coating and absorption action of explosive components.

In order to research the effect of contents and particle sizes of Al powder on the air blast property of explosive, over-pressure, pressing time and impulse of aluminized explosives with different formula were tested and com-pared in this article.The result shows that explosive containing Al at the range of 30%-35%( mass fraction) has higher over-pressure and impulse than other explosive.With the increase of Al content (mass fraction is higher than 35%), over-pressure and impulse decrease.Free-field sensor shows that explosive containing 30%Al (mass fraction) gives rise to the highest over-pressure and impulse values in 4.5 m distance.Moreover explosive containing 30% nano-Al (mass fraction) has lower over-pressure and impulse than explosive containing micro-Al.

In order to improve the detonation energy of explosive, based on the factors affecting boron-reactivity in explosion, through selecting particle size and purity, adding reactive metal, preparing hydrogen-alloy containing boron, using fluorine-binder, the boron-oxidation and reactivity during explosion was improved. The under-water explosion results show that, detonation energy output of boron-explosive can be effectively increased by above ways.

The process and characteristics of deflagration-to-detonation transition(DDT)in high density and shaped explosives were analyzed.The effect of desensitizer and two charging methodology which involves melt cast-ing and press loading on DDT were considered by means of electrical pins.The detonation-induced distances in dif-ferent conditions were also compared.The results show that detonation is induced by shock waves deriving from the accumulation of combustion compression waves,which is the primary mechanism for the DDT in high density and shaped explosives.The detonation-induced distance would be longer when desensitizer was added in explosives,be-cause the desensitizer has big heat capacity and small thermal conductivity.The melt casting explosive is easier to be crushed which will increase the burning area and combustion speed,as the compression strength of melt casting explosive is lower and crisper than press loading explosive.The melt casting explosive tends to reduce detonation-induced distance.

To study the effective regulation and control technology of the deflagration to detonation transition (DDT) process for DNTF-based composite explosive,the effect of ignition charge mass,DDT tube wall thickness constraint and molding way etc.on the performance of DDT for DNTF-based composite explosive was investigated by the coaxial ionization probe test technology.The test results were analyzed from the view of the change in rupture state of DDT tube,wave front velocity at different location of DDT process and inducement detonation distance etc.Results show that the DDT tube wall thickness constraint has no significant effect on the inducement detonation distance of DDT for DNTF-based composite explosive,which is at about 375 mm,but decreasing wall thickness can make the duration time of deflagration stage increase and the initial velocity to detonation reduce to 551 5 m · s-1.Increasing ignition charge mass has no significant effect on the reaction violence of DDT for DNTF-based composite explosive,but it can reduce the duration time of initial combustion and detonation induced distance.The duration time of initial combustion,duration time of deflagration and detonation induced distance of the pressed molding specimen are greater than those of the cast specimen,but there is no obvious difference in the violence of the reaction.

To obtain the initiation respone rule of explosive compound under the action of plasma,the plasma initiation experi ments of explosive compound were performed using electrical exploding of nickel-chromium (Ni-Cr) and tungsten (W) wires as a plasma generating source,the voltage and current of plasma were measured by oscilloscope,and whether explosive detonation was judged by witness plates.Results show that the ability of octogen (HMX) initiated by Ni-Cr wire plasma is stronger than that of HMX nitiated by W wire plasma.When the initiation of HMX with particle size of 140 iμm and 21 μm and of 10％ charge density difference is selected,and lower charge density and smaller particle size are used,the plasma initiation respone of HMX is more intense.HMX,1,1-diamino-2,2-dinitroethylene(FOX-7),N-guanylureadinitramide(FOX-1 2),2,6-diamino-3,5-dinitropyrazine1-oxide(LLM-105)and triaminotrinitrobenzene(TATB) can be initiated by plasma.2,4-dinitroanisole(DNAN) is ignited by heat of electrical exploding wire.The order of Ni-Cr wire plasma initiation sensitivity is HMX＞LLM-105 ≈ FOX7＞FOX-12＞TATB.The mechanism of explosive initiated by plasma is inferred as mixed initiation mechanism.A particles combustion model based on plasma is proposed.

To investigate the effect of Al powder content on the explosion reaction mechanism of HMX based aluminized explosive in vacuum environment ,the explosion field pressure and temperature of four kinds of aluminized explosives of alu -minum mass fraction as 15% (OA1) ,20% (OA2) ,25% (OA3) and 30% (OA4) were measured in a sealed explosion cham-ber ,and explosion gas products of explosive were collected and analyzed .The results show that the quasi-static pressure value decreases in the order of OA2 > OA1 > OA3 > OA4 ,meaning that explosive OA2 has the greatest explosion power . The equilibrium temperature of explosion field decreases in the order of OA 4 > OA3 > OA2 > OA1 ,indicating that the e-quilibrium temperature increases with the increase of aluminum content in the explosive .The first peak temperature of the four explosivesase decreases in the order of OA 1 > OA2 > OA3 > OA4 .For the time required to the first peak temperature , explosive OA1 and OA2 are far faster than explosive OA3 and OA4 .Except explosive OA1 ,other three explosives appear the secondary peak .The part of aluminum in the explosive of aluminum mass fraction as 15% and 20% are reacted in ad-vance .The reaction ratio of Al powder decreases in the orde of OA1 > OA2 > OA3 > OA4 ,indicating that with the increase of aluminum powder content ,the completeness of Al powder reaction decreases .

In order to investigate the influence of nano-aluminum on the detonation energy of explosive, RDX-based explosive containing nano-aluminum and micron aluminum were prepared and used in the under-water detonation experiment. Shockwave energy and bubble energy of explosives with different components of nano-aluminum and micron aluminum were measured. Effect of nano-aluminum content on the energy output in under-water detonation was also analyzed. It can be found that shockwave energy and bubble energy of explosives containing 20%-40% ( mass fraction) nano-aluminum are lower than those of explosives containing 20%-40% ( mass fraction ) micron aluminum, and the difference increases with the raise of aluminum content. When the mass fraction of aluminum powder is 30% or 35%, explosives with the mixtures of nano-aluminum and micron aluminum have higher total energy in underwater detonation, and the optimal mass fraction of nano-aluminum is 10%. Results also show that when the mass fraction of aluminum powder is 35% [m (micron aluminum)︰m (nano-aluminum) = 25︰10], underwater detonation energy of the explosive is the highest.

为研究温压炸药的爆炸特性,将25 g温压炸药在5.8L的密闭爆炸罐中引爆,测试了真空和空气环境下的爆炸压力和爆炸温度,并通过气相色谱分析了爆炸后的气体产物.实验结果表明,温压炸药在空气环境下的平衡压力和平衡温度明显高于真空环境,并且空气中的氧气参与了炸药中铝粉的氧化反应,说明温压炸药在空气环境下存在后燃效应.

为了研究配方组分对二硝基呋咱基氧化呋咱(DNTF)基复合炸药燃烧转爆轰性能的影响,设计了AP和Al粉摩尔比分别为0.306、0.414、0.574的三种配方.采用同轴电离探针测试技术,对这三种DNTF基复合炸药配方进行了燃烧转爆轰性能试验.从燃烧转爆轰过程中波阵面传播速度及诱导爆轰距离的变化分析了AP和Al粉摩尔比对炸药燃烧转爆轰的影响.结果表明,随着炸药配方中AP和AI摩尔比从0.306增大到0.574,炸药初始燃烧持续时间从1065 μs增大1395 μs,燃烧速度从141 m·s-1减小到108 m·s-1,但对流燃烧段和爆燃段持续时间快速减小,对流燃烧速度从500 m·s-1增加到1668 m·s-1,爆燃速度从3000 m·s-1增加到4800 m·s-1,发生燃烧转爆轰的诱导爆轰距离从675 mm左右减小到425 mm左右.

To investigate the initiation characteristics of FOX‐7 and RDX based aluminized explosive initiated by shock waves ,the shock wave sensitivity test and shock initiation test were carried out .Combining shock wave atten‐uation characteristics in aluminum ,the critical gap thickness and the critical initiation pressure of FOX‐7 and RDX based alminized explosive were determined .The change in pressure history of initiation to steady detonation process was recorded through manganin piezoresistance gauges .The results show that the critical gap thickness of FOX‐7 and RDX based explosive is 37 .51 and 34 .51 mm ,respectively ,and the corresponding critical initiation pressure is 10 .91 and 11 .94GPa respectively .For FOX‐7 ,when the initiation pressure is 11 .58GPa ,the distance‐to‐detonation is from 25 .49mm to 30 .46 mm ,the detonation pressure after steady detonation is 27 .68GPa ,while the detonation velocity is 8063m/s .For RDX based aluminized explosive ,when the initiation pressure is 14 .18GPa ,the distance‐to‐detonation is 17 .27 mm to 23 .53 mm ,the detonation pressure after steady detonation is 17 .16GPa ,while the detonation velocity is 6 261 m/s .