纳米Al对RDX基炸药机械感度和火焰感度的影响

采用机械混合法制备了含纳米Al的RDX基混合炸药,测试了其机械感度和火焰感度,用扫描电镜表征了纳米Al及其炸药的表面形貌,分析了感度变化的原因。结果表明,加入纳米Al后,RDX基炸药的撞击感度、摩擦感度和火焰感度增大;随着纳米Al含量的增加,撞击感度、摩擦感度和火焰感度明显增大;且含纳米Al炸药的撞击感度、摩擦感度和火焰感度均高于含微米Al炸药。纳米Al及含纳米Al炸药均存在微量团聚现象,在一定程度上影响了含纳米Al的RDX基炸药的感度。     

黏结剂影响混合炸药低速撞击响应敏感性研究

为了研究黏结剂对炸药低速撞击响应的影响,采用自行研发的落锤式撞击感度装置对含不同黏结剂炸药的撞击感度进行了研究,对比了相同配比下含不同黏结剂药柱的响应敏感性,分析了不同黏结剂对炸药低速撞击响应的影响规律,研究了不同黏结剂的作用机理。结果表明,含增塑剂的黏结体系使炸药更加钝感,SA黏结剂对炸药低速撞击响应的钝感效果最好。     

RDX和铝含量对RDX基含铝炸药热爆发温度的影响

通过热爆发延滞期试验测定了含铝炸药的5s延滞期热爆发温度Tb,研究了RDX和铝粉含量对热爆发温度的影响.结果表明,随着RDX含量的增加,Tb先下降后升高,获得了描述Tb与RDX和铝粉含量关系的线性经验方程.认为在热爆发试验中体系是从含能材料热分解和加热介质两个途径获得能量(热量),前者与含能反应物的含量有关,后者与体系...     

超细RDX/Al混合炸药的制备及性能

以超细RDX为主体炸药,通过添加Al粉,干法工艺制备出超细RDX/Al混合炸药;对制得的样品进行了撞击感度、摩擦感度测试。实验结果表明,相对超细RDX,超细RDX/Al混合炸药的撞击感度和摩擦感度有一定程度的降低。     

FOX-7和RDX基含铝炸药的冲击起爆特性

为研究FOX-7和RDX基含铝炸药的冲击起爆特性,对其进行了冲击波感度试验和冲击起爆试验,结合冲击波在铝隔板中的衰减特性,确定了FOX-7和RDX基含铝炸药的临界隔板值和临界起爆压力,并通过锰铜压阻传感器记录了起爆至稳定爆轰过程压力历程的变化。结果表明,以Φ40mm×50mm的JH-14为主发装药时,FOX-7和RDX基含铝炸药临界隔板值分别为37.51和34.51mm,对应的临界起爆压力为10.91和11.94GPa;起爆压力为11.58GPa时,FOX-7炸药的到爆轰距离为25.49~30.46mm,稳定爆轰后的爆轰压力为27.68GPa,爆轰速度为8 063m/s;起爆压力为14.18GPa时,RDX基含铝炸药的到爆轰距离为17.27~23.53mm,稳定爆轰后的爆轰压力为17.16GPa,爆轰速度为6 261m/s。     

热老化对HMX基高聚物黏结炸药撞击感度的影响

参照GJB 736.8—1990的试验方法,对奥克托今(HMX)基高聚物黏结炸药在71℃高温条件下进行了长达203 d的加速老化试验,每隔一定时间测定其撞击感度。研究发现:炸药的撞击感度在加热到147 d以后有下降的趋势,与老化前相比下降了20%,但初期下降比较明显,后期下降比较缓慢,主要是由于热老化首先引起炸药中硝化棉分解,硝化棉的分解产物进一步引起HMX分解。     

黏结剂对含铝炸药造型粉流散性和堆积密度的影响

为了研究黏结剂对含铝炸药造型粉流散性和堆积密度的影响,使用炸药造型粉流散性测量仪,以A-Ⅸ-Ⅱ炸药为参比标准,对使用不同黏结剂体系制造的含铝炸药造型粉进行分析测试.结果表明,使用硬脂酸和聚异丁烯黏结剂体系,含铝炸药造型粉的流散性与A-Ⅸ-Ⅱ炸药相当,而堆积密度明显优于A-Ⅸ-Ⅱ炸药.采用该黏结剂体系制备出的含铝炸药造型粉更适合分步压装装药工艺.     

纳米LaCoO3对RDX基混合炸药的热分解特性和感度的影响

用DSC和DTA研究了LaCoO3对含AP的RDX基混合炸药热分解特性的影响。结果表明,纳米LaCoO3对含有AP的RDX基爆炸混合物的热分解具有一定的催化作用;纳米LaCoO3使RDX基混合炸药的撞击感度和热感度降低,摩擦感度增大。     

包覆工艺对HMX基含铝炸药燃烧能量的影响

以石蜡作包覆剂,采用两种包覆工艺制备了的4种HMX基含铝炸药,用小型密闭燃烧装置测试了其燃烧过程中压力随时间的变化,通过比较准静态压力得到其燃烧能量大小的关系。用气相色谱仪测量气相燃烧产物的含量,通过化学计算研究了不同包覆工艺制备的含铝炸药中铝粉的反应率。用扫描电镜(SEM)表征了含铝炸药的微观形貌。结果表明,黏结剂的包覆工艺直接影响含铝炸药的微观形态;采用包覆工艺1制备的含铝炸药中未包覆的铝粉更有利于在燃烧初期的吸热,使铝粉的反应率提高约5.8%,燃烧总能量也相应提高。     

硝酸酯对RDX基含铝炸药驱动能力的影响

为了研究硝酸酯对RDX基含铝炸药驱动能力的影响,采用圆筒试验研究了含硝酸酯的RDX基含铝炸药加速圆筒壁膨胀速度和格尼能的变化过程,并与不含硝酸酯的RDX基含铝炸药进行了对比,分析了硝酸酯对炸药能量释放特性及金属驱动能力的影响。结果表明,硝酸酯可改善RDX基含铝炸药的铝氧比,改变其反应速率;在反应初期,含硝酸酯的RDX基炸药加速筒壁的速度低于不含硝酸酯的炸药,而在爆炸反应中后期,含硝酸酯的RDX基炸药加速筒壁的速度以及格尼能均高于不含硝酸酯的炸药;含硝酸酯的RDX基含铝炸药的能量释放特性使其适合用于破片战斗部中,可提高其金属驱动能力。     

GAP型交联改性双基推进剂黏合剂的力学性能

将GAP与异氰酸酯预聚后引入双基推进剂黏合剂中,研究了固化剂种类、R值、固化催化剂二月桂酸二丁基锡(T12)的含量和增塑比对黏合剂的交联网络结构参数RNB值和力学性能的影响。结果表明,随着R值以及(T12)含量的增大,黏合剂的RNB值增大。在与NC中活性-OH交联反应时,TDI的反应活性比IPDI的高。GAP-TDI/NC/NG胶片的最大抗拉强度和断裂延伸率分别可达1.09MPa和202.12%,Tg最低为-42.66℃。     

黏结剂对CL-20/FOX-7基PBX性能的影响

为了研究黏结剂对CL-20/FOX-7基PBX性能的影响,分别以Estane、EPDM、ACM、EVA为黏结剂,采用水悬浮法制备了含有不同黏结剂成分的CL-20/FOX-7基高聚物黏结炸药(PBX);采用场发射扫描电子显微镜(SEM)、激光粒度分析仪、X射线衍射仪(XRD)、差示扫描量热仪(DSC)对样品结构、形貌和热分解特性进行了表征;使用撞击感度测试仪、摩擦感度测试仪和小型烤燃实验装置测试了不同样品的机械感度和烤燃特性。结果表明,以EVA为黏结剂制备的CL-20/FOX-7基PBX造型粉颗粒密实,表面光滑且没有脱粘外漏现象,包覆粘结效果最好;以EVA为黏结剂制备的PBX活化能较细化CL-20提高了87.75 kJ/mol,较FOX-7原料提高了42.52 kJ/mol,说明使用EVA的PBX热稳定性较原料有一定提升;同时该PBX样品特性落高(H 50)较细化CL-20提高25.6 cm,摩擦感度爆炸概率降低52%,较使用Estane、EPDM和ACM的PBX样品机械感度更低;使用EVA的PBX药柱在升温速率为6K/min的慢速烤燃条件下,烤燃反应等级为燃烧,说明该配方能够达到烤燃安全试验要求,安全性能较好。     

Combined effect of VA content and pH level of filler on properties of EPDM/SmBO3 and EPDM/ATO composites reinforced by three types of EVA

This study investigates the interaction of vinyl acetic (VA) content of ethylene‐vinyl acetate (EVA), pH level of Samarium borate (SmBO₃), and Sb‐doped SnO₂ (ATO) on reinforcement of peroxide‐cured ethylene‐propylene‐diene rubber (EPDM)/SmBO₃ and EPDM/ATO composites. It was found that EVA could both reinforce mechanical properties of EPDM, and enhance fluidity of gum during processing. During vulcanization, the interaction of VA groups and pH value of filler particles can influence the crosslink density of EPDM composites. In alkaline EPDM/SmBO₃/EVA, VA groups could hydrolyze to produce polyvinyl alcohol and reduce pH level of medium by consuming OH⁻. When dispersed in acidic EPDM/ATO/EVA, VA groups could generate polyunsaturated bonds and acetic acid during vulcanization. The double bonds could react with dicumyl peroxide (DCP) and then boost crosslink efficiency of EPDM composites. Moreover, acetic acid and reduction of pH value could make DCP decompose into ions, and lower crosslink density of EPDM composites. In addition to the contribution of crosslink density, EVA could crystallize in EPDM composites to reinforce EPDM composites. Electric properties of EPDM were also affected. Surface and volume resistivity of EPDM composites decreased with the rise of VA content. As for EPDM/SmBO₃/EVA composites, the growth of VA groups could boost dielectric constant and loss, decrease dielectric strength, due to the enhancement of polarity and reduction of crosslink density. In terms of EPDM/ATO/EVA composites, the EPDM/ATO/EVA14 possesses the highest dielectric constant and loss, and the lowest dielectric strength, because of the competing effect of VA content and crosslink density. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Rheological study on the adhesion properties of the blends of ethylene vinyl acetate/terpene phenol adhesives

Measurements of the shear, tensile, peel, and creep strength of ethylene vinyl acetate (EVA)/CaCO₃/terpene phenol adhesive system at three different ratios [100/60/0 (EVA-O), 80/48/20 (EVA-20), and 60/36/40 (EVA-40) by weight, using wood and aluminum as adherends] were conducted. Over a wide range of temperatures and rates of deformation, adhesion shear, tensile, and peel strength results, as well as the creep response over a broad range of temperature and stresses, were found to yield a single master curve by means of the reduced-variable technique. It was observed that the peak of E′ representing Tg, shifted toward higher temperatures as the amount of terpene phenol in the blend was increased. The most obvious effect of increasing the tackifier resin was the shifting of the adhesion strength master curves to the direction of lower rates. The shift was associated with the rise in Tg as the blend ratio was increased. The influence of the tackifier resin in modifying the viscoelastic properties of the adhesive was further described in a comparison of the adhesion strength master curves with corresponding dynamic viscoelastic curves of the adhesive films. The master curves for the creep response of the adhesives showed that the stress-breaking time relationship shifts toward longer time for EVA-40 with high Tg. Thus, it was found that the strength of adhesion is due mainly to dynamic effects in the adhesive of a viscous nature in the same way to the cohesive strength of the viscoelastic materials. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 409–418, 1998     

Thermal and mechanical properties of uncrosslinked and chemically crosslinked polyethylene/ethylene vinyl acetate copolymer blends

Uncrosslinked and chemically crosslinked binary blends of low‐ and high‐density polyethylene (PE), with ethylene vinyl acetate copolymer (EVA), were prepared by a melt‐mixing process using 0–3 wt % tert‐butyl cumyl peroxide (BCUP). The uncrosslinked blends revealed two distinct unchanged melting peaks corresponding to the individual components of the blends, but with a reduced overall degree of crystallinity. The crosslinking further reduced crystallinity, but enhanced compatibility between EVA and polyethylene, with LDPE being more compatible than HDPE. Blended with 20 wt % EVA, the EVA melting peak was almost disappeared after the addition of BCUP, and only the corresponding PE melting point was observed at a lowered temperature. But blended with 40% EVA, two peaks still existed with a slight shift toward lower temperatures. Changes of mechanical properties with blending ratio, crosslinking, and temperature had been dominated by the extent of crystallinity, crosslinking degree, and morphology of the blend. A good correlation was observed between elongation‐at‐break and morphological properties. The blends with higher level of compatibility showed less deviation from the additive rule of mixtures. The deviation became more pronounced for HDPE/EVA blends in the phase inversion region, while an opposite trend was observed for LDPE/EVA blends with co‐continuous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3261–3270, 2007     

Study on the properties of ethylene‐vinyl acetate rubber vulcanizate filled with superfluous magnesium hydroxide/methacrylic acid

Ethylene‐vinyl acetate rubber (EVM) vulcanizates cured by dicumyl peroxide (DCP) with excellent mechanical properties were obtained by adding superfluous magnesium hydroxides (MH)/methacrylic acid (MAA). Different factors such as the DCP content and MH content were investigated to reveal their effects on the properties of the MH/MAA‐filled EVM vulcanizates. The formulation of DCP of 2 phr, MH of 60 phr, and MAA of 5 phr is recommended for the EVM vulcanizates with excellent mechanical properties. The stress relaxation and stress softening behavior of MH/MAA‐filled EVM vulcanizates were studied. The stress relaxation and stress softening became faster and more obvious with increasing MH content. The hot air aging resistance of EVM vulcanizates filled with different fillers such as silica and high abrasion furnace were compared, and the MH/MAA‐filled EVM vulcanizates had the best aging resistance at 40‐phr filler content. The MH/MAA‐filled EVM vulcanizates had excellent flame retardancy due to the high MH content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

氧化石墨烯对RDX/PMMA安全性能及力学性能影响

为改善RDX的安全性能和力学性能,采用乳液聚合法制备RDX/聚甲基丙烯酸甲酯/氧化石墨烯(RDX/PMMA/GO)微球,并用相同方法制备了RDX/PMMA复合粒子进行对比;通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)和差示扫描热量仪(DSC)对样品进行表征,并测试其撞击感度和药柱的静态力学性能。结果表明,包覆后RDX/PMMA微球形貌趋于球形,RDX/PMMA/GO粒子存在明显的层状皱褶;RDX晶型均未发生改变;与原料RDX和RDX/PMMA相比,RDX/PMMA/GO微球的表观活化能分别提高22.16kJ/mol和15.17kJ/mol,升温速率趋近于0时的峰温和热爆炸临界温度与原料RDX相比分别提升6.45℃和6.23℃;特性落高由包覆前的26.74cm分别提至62.95cm和78.52cm,撞击感度明显降低。RDX/PMMA/GO抗压强度比RDX/PMMA增加了7.5MPa,表明GO的加入对复合材料的力学性能提升明显。     

Effect of flexibility of ethylene vinyl acetate and crystallization of polypropylene on the mechanical properties of i‐PP/EVA blends

Polymer blend technology has been widely used for the past several years for the modification or enhancement of mechanical properties of polymers to obtain an overall balance of properties over those of the constituents. Despite its interesting mechanical and thermal properties, the impact strength of polypropylene leaves wide scope for improvement. A series of blends of ethylene vinyl acetate (EVA) copolymer with an impact grade of isotactic polypropylene (i‐PP) were prepared by single screw extrusion at 0–0.32 volume fraction of the dispersed phase. The mechanical properties such as tensile behavior, elongation‐at‐break, and impact strength of these blends systems as well as crystallinity were evaluated. Crystallinity data have been used in greater depth to support the mechanical properties. Differential scanning calorimetry studies conducted to study the modification in crystallinity of the crystalline component, i‐PP, of the blend revealed that the rubber component of the blend enhanced the crystallinity of i‐PP phase by providing sites for nucleation. Tensile modulus and strength decreased while the impact strength and breaking elongation enhanced with blending elastomer concentration. The improved properties of these PP/EVA blends are encouraging for carrying out further work on this system (composites) and suggest potential high impact strength applications for PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012