The Effects of TATB Ratchet Growth on PBX 9502

PBX 9502 is a plastic‐bonded explosive that contains 95 wt.‐% TATB, a graphitic‐structured high explosive known to undergo “ratchet growth,” i.e., irreversible volume change that accompanies temperature excursions. Earlier studies have reported changes in TATB‐based composites as a function of thermal cycling and density change, however, a clear distinction between density and ratchet‐growth effects has not been made. In the work reported here, an “as‐pressed density” baseline for the mechanical response of recycled PBX 9502 is established over a density range of interest, then high‐density specimens are thermally cycled between −55 and 80 °C to achieve “ratchet‐grown” parts in the same low‐density region. As‐pressed and ratchet‐grown specimens with identical densities are then analyzed using microX‐ray computed tomography and USANS techniques to obtain information about pore‐size distributions. Data show that after ratchet‐growth, PBX 9502 specimens contain, in general, more numerous and smaller voids than specimens that were pressed with lower compaction pressures to match the same density. The mechanical response of the ratchet‐grown material is consistent with damage, showing lower tensile stress and modulus, lower compressive modulus, and higher tensile and compressive strain, than as‐pressed specimens of the same density.     

Influence of Recycled ABS Added to Virgin Polymers on the Physical,Mechanical Properties and Molding Characteristics

Reuse of recycled polymers is steadily increasing. In this study, two different ABS virgin materials are considered. Then, blends of varying proportions of ABS recycled resins (0–50%), obtained from the gate and runner materials of products, was added to virgin resin to investigate the effect of various compositions of virgin ABS and recycled polymers on the physical and mechanical properties of the final blend. Three different rib and closure organization of boss of the reinforcement structures were designed and injection molded under blends of varying proportions of the ABS recycled resins to do the torsion test by Air-Torsion tools. In addition, molding characteristics were also examined. The results show that there is no obvious effect of recycled ABS percentage (by weight) on the tensile strength, elongation at yield, flexural strength, flexural modulus, and impact strength. However, the torsion strength for rib and closure organization of boss of the reinforcement structures decrease with increasing recycled ABS weight percentage. On the other hand, hardness, glass transition temperature, and melting flow index of recycled ABS increase with as the percentage (by weight) of recycled material increase. The impact strength was found to vary with the recycled ABS loading. The injection pressure decreases with increasing the content of recycled resin under some specified molding conditions.     

PBX巴西试验与直接拉伸试验的比较

为了研究用巴西试验测量PBX炸药间接拉伸强度的有效性,对PBX炸药进行了巴西试验和直接拉伸试验.结果表明,巴西试验测得的间接拉伸强度为3.60MPa,直接拉伸强度为5.50MPa,间接拉伸强度约为直接拉伸强度的65%.裂纹分析表明,巴西试验后PBX样品端面的初始开裂发生在中心点外,如偏心破坏,或者应力集中区的破坏,不满...     

A Study of FTIR,Thermal Properties and Natural Weathering Test on NBRVirgin/Recycled with SBR Blends

The effects of styrene butadiene rubber/virgin acrylonitrile butadiene rubber (SBR/NBRv) blends and styrene butadiene rubber/recycled acrylonitrile butadiene rubber (SBR/NBRr) blends on properties such Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were carried out. Results indicated that, based on intensity of amine peak from FTIR at 85/15 blend ratio (R15) revealed optimum formation of crosslink between SBR and NBR either using virgin or NBRr. TG thermograms of SBR/NBRv blends of all ratios showed better onset thermal stability than SBR/NBRr blends. The change in the horizontal baseline from high to low energy level occurred in virgin NBR blends because the amount of reactive sites available in virgin NBR is higher compared to NBRr. Meanwhile NBRr blends showed T_c because the amount of crosslink occurred in these blends were slightly lower than NBRv blends. Up to 25 phr of NBRr, the tensile strength and elongation at break (E_b) retention of SBR/NBRv blends was better than SBR/NBRr blends after 6 months' weathering test except for M100. The scanning electron microscopy on the surface of both blends after 6 months exposure indicated that the severity of the crack was minimal for SBR/NBRr blends compared to SBR/NBRv particularly at 50/50 blend ratio designated the SBR/NBRr blends that contained more NBRr particles could reduce the degradation towards natural weathering.     

Dead Zones in LX‐17 and PBX 9502

Pin and X‐ray corner turning data have been taken on ambient LX‐17 and PBX 9052, and the results are listed in tables as an aid to future modeling. The results have been modeled at 4 zones/mm with a reactive flow approach that varies the burn rate as a function of pressure. A single rate format is used to simulate failure and detonation in different pressure regimes. A pressure cut‐off must also be reached to initiate the burn. Corner turning and failure are modeled using an intermediate pressure rate region, and detonation occurs at high pressure. The TATB booster is also modeled using reactive flow, and X‐ray tomography is used to partition the ram‐pressed hemisphere into five different density regions. The model reasonably fits the bare corner turning experiment but predicts a smaller dead zone with steel confinement, in contradiction with experiment. The same model also calculates the confined and unconfined cylinder detonation velocities and predicts the failure of the unconfined cylinder at 3.75 mm radius. The PBX 9502 shows a smaller dead zone than LX‐17. An old experiment that showed a large apparent dead zone in Composition B was repeated with X‐ray transmission and no dead zone was seen. This confirms the idea that a variable burn rate is the key to modeling. The model also produces initiation delays, which are shorter than those found in time‐to‐detonation.     

压制过程中PBX炸药颗粒的破碎及损伤

用扫描电镜及激光粒度仪研究了PBX炸药在不同压制条件下的微观结构变化及粒度分布。结果表明,随着成型试件密度的增加,晶体的破碎、损伤情况加重;成型试件中HM X的平均粒径随着压力的增加而减小(压制前的33.05μm到250M Pa压制后的16.92μm);在相同压力条件下,热压(70℃)制品的密度更高,但晶体的破碎却更小,热压(70℃)制品中HM X的平均粒径要大于冷压(25℃)制品中HM X的平均粒径。     

TATB基PBX复合材料的微观结构分析

报道了在不同颗粒尺寸TATB基PBX体系制备过程中的微观结构,重点研究了高填充率PBX体系．结合多种高分辨率的微观结构与组分表征手段如SEM、EDX、XRD等,观察到了一些典型的原生和再生缺陷以及黏结剂的分布特性,初步建立了颗粒、造型粉、药柱之间系统表征的联系,为材料宏观性能的改进提出了新的途径。     

PBX-9404和PBX-9502炸药拐角性能的数值模拟

借助于有限元动力学软件LS-DYNA,通过Mushroom试验模拟,研究了PBX-9404和PBX-9502的拐角性能.结果显示,在相同试验条件下,PBX-9502的出射角小于PBX-9404,PBx-9502具有明显的死区,表明PBx-9404的拐角性能优于PBx-9502.传爆药直径和炸药半球直径变化对表征炸药拐角...     

Microstructure of the HMX‐Based PBX KS32 after Mechanical Loading

Non‐destructive X‐ray diffraction techniques were applied in order to monitor the influence of mechanical and shock‐loading on the microstructure of the plastic‐bonded high explosive KS32. The investigations uncovered damage to embedded coarse HMX crystals and to the binder system HTPB‐IPDI. Damage to the crystals occurred already during the kneading process in terms of deformation twinning. On higher loading between 400 MPa (static) and 480 MPa (dynamic) also crystal fracture was observed. The change in the binder structure was found after both static and dynamic loading, but not in the cured, differently kneaded samples. Moreover, the change in binder structure after dynamic loading was verified by dynamic mechanical analysis, and interpreted as a partial damage of the binder rubber shell around the explosive particles. The results are compared to literature data from imaging techniques.     

PBX炸药概述及其发展与前景

概述了高聚物黏结炸药PBX的特点、成分与分类,总结了它的研究发展,突出体现了含能材料用作PBX炸药的主要添加剂——黏结剂和增塑剂的热点,并以叠氮类含能化合物为主要研究方向：     

低拉伸应力下PBX的老化实验研究

为了研究PBX在超长时低应力拉伸下的老化问题,设计了一种能进行超长时恒定拉伸应力加载的新实验装置,并验证了装置的可靠性.对以HMX和TATB为基的PBX炸药进行不同拉伸应力下的常温长时加载和45℃下的高温长时加载试验,研究了应力水平和温度环境对样品抗长时拉伸能力的影响,比较了相同条件下模压样品和等静压样品抗长时低应力拉伸的能力.结果表明,本实验能够有效研究PBX在低应力拉伸下的承载能力,并获得了在一定温度一定拉伸应力条件下PBX的老化寿命.     

TNT、PBX和Hexel空中爆炸冲击波参数的实验研究

利用空中爆炸测试系统,对相同质量不同密度不同装药的TNT、PBX和Hexel进行了空中爆炸参数测试。比较了3种炸药在相同测点处的冲击波峰值超压和冲量的大小。研究了冲击波峰值超压和冲量与比例距离的关系。结果显示,TNT的冲击波峰值超压和冲量明显低于PBX和Hexel;在比例距离（1．8～4．9）m／kg^1/3。范围内,Hexel的冲击波峰值超压和冲量高于PBX。当比例距离为6．1m／kg^1/3时,Hexel的冲击波峰值超压和冲量与PBX相当。     

PBX压缩疲劳过程中的红外热像试验研究

采用红外热像仪对PBX块状试样在单轴压缩载荷下的疲劳过程进行了试验研究.结果表明,PBX药柱在压缩疲劳过程中会出现明显的温度升高现象,红外热像技术可实时监测药柱表面温度场的变化;PBX的疲劳温升与疲劳加载的频率、应力及试样状态有很大关联性,最大温升值随着疲劳加载的频率和加载应力幅值的增大而(提高.)     

Comparison of Properties of Polypropylene (PP)/Virgin Acrylonitrile Butadiene Rubber (NBRv) and Polypropylene (PP)/Recycled Acrylonitrile Butadiene Rubber (NBRr) Blends

The comparison properties of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) blends and polypropylene/virgin acrylonitrile butadiene rubber (NBRv) blends were investigated. The tensile properties such as tensile strength, tensile modulus and elongation at break of PP/NBRv blends are higher than PP/NBRr blends. However, PP/NBRv blends exhibit lower stabilization torque and higher swelling percentage than PP/NBRr blends. Based on SEM, a finer morphology was observed in PP/NBRv blends in comparison with the PP/NBRr blends. The thermal stability of PP/NBRr is better than that of PP/NBRv blends.     

Time‐Evolution of TATB‐Based Irreversible Thermal Expansion (Ratchet Growth)

TATB is an insensitive high explosive, attractive for use because of its safety aspects. TATB compactions, with or without binder, undergo irreversible volume expansion (or ratchet growth) upon thermal cycling. In the past, experimental elucidation of this phenomenon has focused on irreversible expansion as a function of the number of thermal excursions over a given temperature range, where growth is asymptotic with increasing cycle number. In this paper, we demonstrate that ratchet growth also occurs as a function of time at constant temperature, and that growth is substantial at elevated temperatures. We have measured strain response in PBX 9502, a TATB‐based composite, by performing thermal‐cycling tests with different durations at high temperature. Irreversible growth arises from the thermal ramps themselves (increasing and decreasing), as well as from the subsequent isotherms. PBX 9502 specimens with previously‐identified TATB texture/orientation were used in order to eliminate and/or evaluate texture as a variable. Measurements were also performed on dry‐pressed TATB (no binder) to confirm that expansion as a function of time (constant temperature) is not caused by the binder. A simple analysis of the time‐response data demonstrates consistency in the results. We propose that the primary driving force for irreversible expansion is the proximity of the current strain value (due to thermal history) to the strain saturation point of the current cycle (i.e. strain at infinite high‐temperature hold times or an infinite number of cycles). Such tests should aid in the understanding and modeling of ratchet growth response in these materials.     

浇注PBX药浆适用期的研究

对浇注PBX用HTPB—TDI黏结剂体系进行了研究。通过选择合适的催化剂二月桂酸二丁基锡（T-12）缩短HTPB—TDI黏结剂体系的固化周期;通过选择有效的抑制剂乙酰丙酮（HAA）与催化剂T-12联合使用延长HTPB—TDI黏结剂体系的适用期,并达到缩短浇注PBx固化周期的目的。通过测定HTPB—TDI黏结剂体系的黏度,评价了加入催化剂和抑制剂方式对浇注PBX黏结剂体系的适用期的影响,找出合适的T-12与HAA摩尔比为4：1。     

Thermal Expansion of LX‐17, PBX 9502, and Ultrafine TATB

A large quantity of linear strain and LCTE data from −55 °C to 75 °C on LX‐17, PBX 9502 and ultrafine TATB (ufTATB) is presented. Axial and diametral measurements are blended to give final densities, which agree with the liquid immersion values of Baytos et al. The nominal densities at 21, −55 and 75 °C in g ⋅ cm⁻³ are: LX‐17 1.90, 1.920, 1.874; PBX 9502 1.89, 1.907, 1.867; ufTATB 1.80, 1.822, 1.778. Data taken radially show more thermal expansion than that taken transversely in cut‐up parts; both must be combined to get the density. There is no difference between virgin and recycled TATB. Rachet growth data is presented, both at low pressure and at higher pressure, where the swelling is diminished. A Kel‐F strain curve is presented and the theoretical maximum densities are computed.     

HMX/TATB基PBX的感度与表面形态的关系探索

报道了以HMX/TATB基的PBX中,蜡的加入量和加入方式对配方的机械感度如撞击感度、摩擦感度、特性落高有明显的影响,但对配方的热感度如5s爆发点、1000s热爆炸临界温度影响不大。同时结合扫描时局镜（SEM）和光电子能谱（XPS）的测试结果分析了造型粉的表面包覆形态和感度之间的关系。     

核壳型HMX@TATB复合炸药造型粉制备技术研究

核壳型HMX@TATB复合炸药不仅能够显著降低HMX炸药的感度,还能有效保持HMX的高能量密度水平,在未来钝感弹药和安全型高能推进剂领域展现了较好的应用前景,而核壳型HMX@TATB复合炸药基PBX的制备研究对其相关性能测试和后期应用研究起重要作用。本研究探索了核壳型HMX@TATB复合炸药为基PBX造型粉制备过程中的转速、温度和粘结剂的滴加速度等工艺参数对造粒包覆的影响,得到了稳定的百克级核壳型HMX@TATB为基PBX造型粉的造粒工艺。     

RDX基PBX炸药烤燃试验与数值计算

对RDX基PBX炸药进行了烤燃试验,建立了炸药烤燃计算模型,其中加入了Frank-Kamenetskii、SestakBerggreen和McGuire-Tarver反应模型,采用流体力学计算软件Fluent进行了数值模拟.试验结果表明,PBX炸药在1K/min升温速率下发生剧烈反应的时间为176.0min,此时试样中...