相稳定硝酸铵表面改性及在推进剂中的应用

为增加相稳定硝酸铵(PSAN)表面与黏合剂体系的界面粘接,选择能与PSAN发生氢键作用的KH792硅烷偶联剂包覆PSAN,并用扫描电镜、X射线光电子能谱等表征改性效果.结果表明,改性PSAN表面包覆形貌变化很大,包覆膜较完整,与NG和DEGDN的接触角分别下降56%和63%, 吸湿性下降约15%.研究了改性PSAN对BAMO-THF/PSAN推进剂工艺和力学性能的影响,发现抗拉强度提高约65%,脱湿比下降约20%,工艺性能也有所改善.     

聚醋酸乙烯酯包覆 DHG 的研究

研究了乳液聚合聚醋酸乙烯酯对二羟基乙二肟的包覆。采用电子能谱仪、透射电镜研究了包覆效果。二羟基乙二肟包覆后应用在端羟基粘合剂中，可改善复合固体推进剂的力学性能。     

高能氧化剂表面包覆研究进展

表面包覆是降低高能氧化剂机械感度的一种重要方法.对推进剂组分中的氧化剂固体颗粒进行表面包覆,不仅能降低单组分的机械感度,也能提高推进剂的力学性能和改善推进剂工艺性能.综述了高能氧化剂的表面包覆方法及其研究进展.     

蒙脱土对丁羟推进剂力学性能和流变性能的影响

为提高丁羟推进剂的力学性能,利用有机蒙脱土(OMMT)可被端羟基聚丁二烯(HTPB)剥离为纳米片层的特性,将OMMT引入到HTPB推进剂中,制备了OMMT改性的HTPB推进剂;利用拉伸试验机、流变仪研究了OMMT的引入对推进剂力学性能和流变性能的影响。结果表明,OMMT的引入可以显著提高HTPB推进剂的力学性能,同时起到增强增韧的效果,当在HTPB中引入质量分数2%的OMMT时,推进剂的力学性能最佳,最大拉伸强度和断裂伸长率分别提高了约78%和21%,其原因在于在黏结剂基体中,蒙脱土以纳米片层的形式存在于体系中,增强黏结剂基体的力学性能,从而提高推进剂的力学性能;OMMT的引入还可改善推进剂药浆的工艺性能,降低OMMT推进剂药浆的混合黏度,并加快推进剂药浆的固化速率。引入OMMT后,推进剂药浆的适用期由6.25h降至4.16h。     

白度化微胶囊红磷阻燃剂的制备及其应用

研究了白度化微胶囊红磷阻燃剂的制备方法,并研究了其对聚丙烯材料的氧指数影响。采用XPS、SEM、TG、磷化氢释放量、抗氧化性、吸湿性等对其进行了表征,结果表明:红磷阻燃剂微胶囊包覆效果有明显改善作用,其吸湿性、抗氧化性、PH3释放量均大大减少;XPS图谱表明99.5%的红磷已被包覆;扫描电镜显示红磷阻燃剂平均粒径为0.24μm;TG显示红磷阻燃剂的着火点已提高到435℃;氧指数测试结果表明:经红磷阻燃剂阻燃后,聚丙烯的氧指数已提高到28。     

白度化微胶囊化红磷阻燃剂的研制

描述了白度化微胶囊红磷阻燃剂的制备方法,采用XPS、SEM、TG、磷化氢释放量、抗氧化性、吸湿性等对其进行了表征.结果表明红磷阻燃剂微胶囊包覆效果有明显改善作用,其吸湿性、抗氧化性、PH3释放量均大大减少,XPS图谱表明99.5%的红磷已被包覆,扫描电镜显示红磷阻燃剂平均粒径为0.24 μm,TG显示红磷阻燃剂的着火点已提高到435℃.     

嵌段型中性聚合物键合剂在NEPE推进剂中的初步应用

采用扫描电镜和力学性能测试技术,对比研究了嵌段型中性聚合物键合剂QD–06和中性聚合物键合剂(NPBA)对黑索今(RDX)粒子的包覆性能以及在硝酸酯增塑聚醚(NEPE)推进剂中的键合效果。结果表明,QD–06包覆RDX的表面更加圆滑,颗粒间团聚现象明显,其包覆能力优于NPBA;QD–06能显著提高固体推进剂的常温和高温力学性能,大幅改善推进剂脱湿现象,其键合效果优于NPBA。     

环境湿度对NEPE类固体推进剂力学性能的影响

采用动态吸湿性能分析法测定高能推进剂的吸湿性,以典型配方NEPE(硝酸酯增塑聚醚)推进剂和低易损性推进剂为研究对象,考察了湿度对其力学性能的影响。结果表明:典型配方NEPE推进剂和低易损性推进剂吸湿性差别很大;高湿环境下,2种高能推进剂的力学性能变化差异明显;经干燥处理,典型配方NEPE推进剂存放3 d后,抗拉强度和伸长率完全恢复,而低易损性推进剂存放10 d,其抗拉强度只恢复至原先的一半。     

含相稳定硝酸铵CMDB推进剂的机械感度和燃烧性能

通过测试撞击感度、摩擦感度和燃速,研究了含相稳定硝酸铵(PSAN)的改性双基(CMDB)推进剂的燃烧性能和机械感度。结果表明,PSAN可改善CMDB推进剂的机械感度;用PSAN作氧化剂,其推进剂的燃速低于RDX作氧化剂的燃速,压强指数高于后者的压强指数;1～5MPa压力范围内随PSAN在配方中含量的增加,推进剂的燃速降低,压强指数升高。     

RDX包覆与某种键合剂的匹配性研究

用PVAM（醋酸乙烯酸－丙烯酸丁酯共聚物）与CAB（醋酸丁纤维素（对RDX进行包覆，并测试了含有包覆球的推进力学性能数据，结果表明PVAM包覆的RDX与键合剂的匹配使用可以改善推进剂的力学性能。     

微胶囊技术在硝酸铵改性中的应用

提出了用聚苯乙烯包覆硝酸铵制备硝酸铵微胶囊的新方法 ,采用电子能谱仪研究了包覆效果 ,并对包覆前后的硝酸铵进行吸湿性测量 ,分析了改性后的硝酸铵吸湿结块性降低的原因和机理。     

硝酸铵氧化剂的表面改性及其吸湿性研究

提出了用硅烷偶联剂Si-K和高分子材料Polym-B对硝酸铵进行双层包覆的新思路;利用光电子能谱仪和扫描电子显微镜表征了包覆效果,结果表明Si-K和Polym-B能对硝酸铵粒子进行很好包覆,在其表面形成均匀而完整的包覆层.通过测量吸湿性和结块性的变化研究了改性效果,数据表明改性后的硝酸铵吸湿性降低了近50%,结块性显著降低.     

A DSC Study on the Effect of RDX and HMX on the Thermal Decomposition of Phase Stabilized Ammonium Nitrate

Phase stabilized ammonium nitrate(PSAN) was prepared by incorporating copper(II) diammine nitrate in the ammonium nitrate(AN) crystal lattice. The effect of two energetic materials viz., RDX and HMX on the thermal decomposition of PSAN was investigated using DSC. The decomposition temperatures of PSAN and RDX are almost in the same temperature range. The decomposition of PSAN is endothermic and that of RDX is exothermic, while that of a 1:1 mixture of the two is exothermic with a net heat release in excess of that of the individual reactions, which is attributed to the combustion reaction among the decomposition products of PSAN and RDX. Though HMX decomposes at a higher temperature, in presence of molten PSAN a substantial portion of it decomposes at a lower temperature along with PSAN with a net excess heat release, again due to the combustion reaction. The kinetic parameters of the two exothermic decompositions were computed using two equations based on variable heating rate method viz., Kissinger and Ozawa equations. The activation energy obtained from Ozawa method was refined by an iteration procedure. There is a close agreement among the values obtained by the three methods. The kinetic parameters for PSAN-HMX mixture are lower, probably due to the effect of its higher heat release.     

Effect of clay on the properties of poly(styrene‐co‐acrylonitrile)–clay nanocomposites

Clay‐dispersed poly(styrene‐co‐acrylonitrile) nanocomposites (PSAN) were synthesized by a free radical polymerization process. The montmorillonite (MMT) was modified by a cationic surfactant hexadecyltrimethylammonium chloride. The structures of PSAN were determined by wide‐angle X‐ray diffraction and FTIR spectroscopy. The dispersion of silicate layers in the polymer matrix was also revealed by transmission electron microscopy (TEM). It was confirmed that the clay was intercalated and exfoliated in the PSAN matrix. The increased thermal stability of PSAN with the addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of PSAN were measured in the frequency range 100 Hz to 1 MHz at 35–70°C. It was found that the dielectric constant from the dipole orientation had been suppressed due to the intercalation of clay. The dielectric loss is strongly related to the residual sodium content of clay, which increases as the sodium content increases by the addition of clay. Copyright © 2004 Society of Chemical Industry     

Preparation and graft‐copolymerization of hydrogenated natural rubber in latex stage

Preparation and graft‐copolymerization of hydrogenated natural rubber are performed in latex stage after removal of proteins from the rubber with urea and surfactant. Hydrogenation of deproteinized natural rubber (DPNR) latex is carried out with palladium catalyst under hydrogen atmosphere. The hydrogenated DPNR (HDPNR) is crosslinked with a peroxide followed by graft‐copolymerization of styrene (Sty) and acrylonitrile (AN) in latex stage in order to prepare a graft‐copolymer of crosslinked HDPNR with poly(Sty‐co‐AN) (HDPNR‐graft‐PSAN). Characterization of the products is performed by nuclear magnetic resonance spectroscopy. The conversion of hydrogenation is investigated with respect to the catalyst feed, acidity (pH), and dry rubber content. In the resulting HDPNR‐graft‐PSAN, mole fraction of AN and Sty is 1.4 and 5.8 mol %, respectively. The graft‐copolymer is used to improve properties of PSAN as an impact modifier. The Charpy impact strength of crosslinked HDPNR‐graft‐PSAN/PSAN is about eight times as high as that of PSAN. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42435.     

Effect of glidants in binary powder mixtures

The intention of this study is to investigate on a particulate level the flow properties of dry powder mixtures consisting of cornstarch and a second nanoscaled material. Special attention is paid to the question on the working mechanism of glidants. In 1974, Rumpf showed that a roughness on the surface of a smooth particle leads to a reduction of its forces of interaction with another particle. The interaction forces are reduced as the surface roughness increases the distance between the centers of gravity of the two interacting particles. Agglomerates as well as the primary particles of materials used as glidants are characterized by diameters in the lower nanometer range. In consequence they are strongly adsorbed at the surface of larger particles and act as a surface roughness. If the effect of a glidant would be due to its ability to act as a surface roughness then all nanoparticles being small enough to reduce the net interaction forces could be used as glidants almost irrespective of their chemical nature. Indeed we have been able to demonstrate that nanoparticles of titanium dioxide, aluminum oxide, silicon dioxide or of carbon black act as glidants. Mixing time directly influences the efficiency of a nanomaterial to act as a glidant. Due to increasing ratio of adhesive force to particle weight with decreasing particle radius, nanomaterials tend to aggregate and agglomerate. With increasing mixing time the size of agglomerates decreases. At the same time the number of primary particles available for adsorption on the surfaces of the cornstarch particles increases. An optimum in flow properties is achieved at a characteristic mixing time. At a further increase in mixing time, the size of agglomerates decreases and the coverage of the cornstarch particles by nanoparticles increases. Eventually cornstarch particles are obtained being completely coated with nanoparticles. The surfaces of these coated particles are smooth. Accordingly they show a poor flow behavior. The property of the nanomaterial to act as a glidant is lost.     

炭黑化学镀铜及性能研究

以甲醛为还原剂,硫酸铜为主盐,采用还原法,在不同种炭黑表面化学镀铜。检测不同种镀铜炭黑的物理性能,包括电阻率、摩擦系数等;利用金相显微镜对各种镀铜炭黑进行金相分析,利用晶粒度评级软件分析镀铜炭黑的平均粒径。结果表明：控制合适的工艺条件,镀铜层能够比较完整地包覆在炭黑粒子及炭黑聚集体的表面,炭黑镀铜率可以高达70％;炭黑粒径越小,单位质量炭黑的比表面积越大,表面活化中心也越多,铜在炭黑表面的包覆效果越好;石墨化后炭黑的镀铜效果较石墨化前有所提高。     

Dispersion copolymerization of acrylonitrile‐vinyl acetate in supercritical carbon dioxide

Dispersion copolymerization of acrylonitrile‐vinyl acetate (AN‐VAc) had been successfully performed in supercritical carbon dioxide (ScCO₂) with 2,2‐azobisisobutyronitrile (AIBN) as a initiator and a series of lipophilic/CO₂‐philic diblock copolymers, such as poly(styrene‐r‐acrylonitrile)‐b‐poly(1,1,2,2‐tetrahydroperfluorooctyl methacrylate) (PSAN‐b‐PFOMA), as steric stabilizers. In dispersion copolymerization, poly(acrylonitrile‐r‐vinyl acetate) (PAVAc) was emulsified in ScCO₂ effectively using PSAN‐b‐PFOMA as a stabilizer. Compared with the precipitation polymerization (absence of stabilizer), the products prepared by dispersion polymerization possessed of higher yield and higher molecular weight. In addition, the particle morphology of precipitation polymerization was irregular, but the particle morphology of dispersion polymerization was uniform spherical particles. In this study, the effects of the initial concentrations of monomer and the stabilizer and the initiator, and the reaction pressure on the yield and the molecular weight and the resulting size and particle morphology of the colloidal particles were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5640–5648, 2006