水性聚氨酯包覆黑索今的性能及影响因素研究

以水性聚氨酯(WPU)乳液作为黑索今(RDX)的包覆材料,以撞击感度和热感度作为衡量指标,采用单因素分析法优选出WPU包覆RDX的最佳工艺条件。结果表明:采用单凝聚法包覆RDX,当RDX的粒度为120~300目(铁筛网)、w(WPU)=2.0%(相对于RDX质量而言)和w(阳离子型表面活性剂)=1%(相对于物质总质量而言)时,RDX的包覆效果较好,此时包覆后RDX的撞击感度和热感度降幅较大。     

改性水性聚氨酯乳液包覆RDX的合成研究

以聚四氢呋喃二醇(PTMG)为聚醚软段、甲苯二异氰酸酯(TDI)为硬段、DMPA(二羟甲基丙酸)为亲水扩链剂、环氧树脂(EP)和硅烷偶联剂为交联扩链改性剂,制取耐水性好、粘接强度高的改性水性聚氨酯(WPU)乳液;并以此作为黑索今(RDX)的包覆剂。结果表明:当w(EP)=6%(相对于物质总质量而言)、w(硅烷偶联剂)=2.0%(相对于物质总质量而言)和w(WPU)=2%(相对于RDX质量而言)时,经改性WPU乳液包覆后的RDX,其成型性、流散性和包覆效果较好,撞击感度和热感度明显降低。     

RDX的TNT包覆钝感研究

为降低RDX的机械感度,维持其爆炸性能,研究了用少量TNT包覆RDX的钝感方法。以RDX为主体炸药成分,以质量分数3％～10％的TNT为含能钝感剂,再加入质量分数2％～3％的含能增塑剂和微量水溶性表面活性剂,利用TNT和含能增塑剂在水中不同温度的熔化和凝固结晶,通过水悬浮分散包覆工艺,将TNT和含能增塑剂包覆在RDX颗粒的表面,制得内层为RDX、外层为TNT的双层混合炸药。分析了包覆钝感的工艺条件及炸药包覆后的粒径和SEM的变化情况。研究表明,该RDX—TNT双层混合炸药的撞击感度可降至20％以下,摩擦感度降至28％以下,压制成药柱的密度为1．73g／m^3,爆速可达8400m／s。     

不同胶粘剂对RDX降感效果的对比研究

为降低RDX(黑索金)炸药的机械感度,分别采用5种惰性胶粘剂[如F2602(氟橡胶)、F2604(氟橡胶)、EPDM3720(三元乙丙橡胶)、PVAc(聚醋酸乙烯酯)和Estane5703(热塑性聚氨酯)等]作为包覆剂,对RDX表面进行包覆处理。研究结果表明:不同胶粘剂均可成功包覆在RDX颗粒表面;包覆RDX的撞击感度随胶粘剂比例增加呈先升后降态势;F2602和F2604包覆RDX的摩擦感度随胶粘剂比例增加而增大,而其他3种胶粘剂的摩擦感度则随之下降。     

硬脂酸包覆超细RDX及其撞击感度

为改善超细RDX的性能,采用硬脂酸(SA)为钝感添加剂,获得了以超细RDX为基的钝感混合炸药.通过测试接触角、计算表面能验证其包覆可行性,SA能够包覆UFRDX.用扫描电镜对包覆后的样品进行表征验证,并测试了SA包覆后的超细RDX的撞击感度.结果表明,其表面形貌得到明显改善,SA可降低其撞击感度,说明钝感剂SA的加入是降低炸药撞击感度的有效方法.     

水性聚氨酯乳液的制备及其在含硝胺推进剂中的应用

以甲苯二异氰酸酯(TDI)、聚氧化丙烯二醇DL-400(Mn=340)、二羟甲基丙酸(DMPA)为主要原料,保持起始时n(NCO)∶n(OH)=1 7∶1,80℃反应1h,1,4 丁二醇(BDO)扩链,水中分散,制得水性聚氨酯乳液PU-1;运用FTIR、1HNMR表征了其结构;采用GPC测定了PU-1的数均相对分子质量Mn为32122,重均相对分子质量Mw为82785,可用作粘附剂。将合成的PU-1乳液应用于复合固体推进剂(NEPE),采用加入十二水硫酸铝钾(明矾)水溶液〔m(明矾)∶m(水)=1∶10〕沉降乳液的方法包覆氧化剂填料黑索今(RDX),使其形成微胶囊;采用SEM观察了包覆结果,发现包覆后的RDX表面圆滑,包覆后的RDX之间流散性较好。通过撞击感度实验,表明包覆后RDX的撞击感度比包覆前下降了28%;通过外壳溶出实验,测得包覆后RDX中聚氨酯包覆层的质量占样品总质量的1 48%,符合军用标准。水性聚氨酯乳液可作为包覆壁材应用于NEPE推进剂中。     

聚氨酯-丙烯酸酯核-壳乳液的制备及其包覆的RDX

以甲苯二异氰酸酯(TDI)、聚氧化丙烯二醇DL-400(Mn=340)、二羟甲基丙酸(DMPA)、1，4-丁二醇(BDO)为主要原料，制得水性聚氨酯乳液(WPU)，用FTIR表征了其结构。以WPU、水、丙烯酸丁酯为原料，分别以AIBN、(NH4)2S2O8-NaHSO3作引发剂，采用种子乳液聚合的方法制备了聚氨酯-丙烯酸酯乳液(PUA)，运用TEM表征了PUA乳液的粒子形态。结果表明：以AIBN为引发剂合成了具有核壳结构的PUA乳液．壳层为黑色的聚氨酯胶粒，核层为白色的聚丙烯酸酯胶粒；而(NH4)2S2O8-NaHSO3引发的乳液不具有核-壳结构，黑白粒子相间分布。采用加入10％明矾水溶液使核-壳乳液破乳的方法包覆RDX，并用SEM观察RDX的表面变化，证实包覆后的RDX表面有均匀的包覆层，且颗粒间流散性较好。     

降感RDX的制备及晶形控制

采用溶剂-非溶剂重结晶方法制备了降感RDX,研究了温度、溶剂、非溶剂、搅拌强度、表面活性剂和加料方式等工艺条件对双重结晶的影响.采用光学显微镜和扫描电镜分析了所得晶体的形貌,测定了其撞击感度.结果表明,采用最佳工艺条件:70℃,二甲基亚砜(DMSO)为溶剂,甲醇为非溶剂,糊精为表面活性剂,搅拌强度1 000 r/min,改善了RDX的晶貌和内部质量,降低了撞击感度.通过控制溶液的初始浓度可制得不同粒度的RDX,粒径为100～120 μm晶体的撞击感度比原料降低了34%.     

BAMO-THF共聚醚原位结晶包覆HMX

为了降低HMX的机械感度,以BAMO-THF共聚醚和甲苯二异氰酸酯(TDI)为包覆材料,用原位结晶方法对HMX颗粒进行了表面包覆,制备了BAMO-THF/HMX复合颗粒。采用扫描电镜(SEM)、傅里叶红外分析仪、X射线衍射(XRD)、激光粒度仪、X射线光电子能谱(XPS)对包覆前后HMX颗粒进行了表征。结果表明,包覆处理后的HMX晶体质量得到明显改善,晶体形貌更规整、颗粒表面缺陷显著减少,其撞击感度和摩擦感度分别从包覆前的88%和92%降到24%和40%。     

喷雾干燥法制备球形RDX的工艺优化

以丙酮为溶剂,采用喷雾干燥法制备了微米级球形RDX,研究了入口温度、进料速率、喷雾气体流速和溶液浓度对所得RDX颗粒形貌的影响。通过扫描电镜(SEM)分析了不同工艺条件下制备的RDX的球形化效果,用DSC分析了其热分解特性,并测试了其撞击感度。结果表明,制备球形RDX的最佳工艺条件为:入口温度为60℃,进料速率为1.5mL/min,喷雾气体流速为357L/h,原料RDX质量分数为1.9%,抽气流速为40m3/h。在此工艺条件下,获得了中值粒径为2.82μm、表面较光滑的球形RDX颗粒。与原料RDX相比,球形RDX的热分解表观活化能降低了2.33kJ/mol,特性落高从19.98cm升至54.70cm,表明球形RDX的撞击感度明显降低。     

Transparent,thermal insulation and UV-shielding coating for energy efficient glass window

Size-controllable double-shell hollow TiO₂@SiO₂ spheres (DHTSs) were fabricated using a simple sol-gel reaction. The size of DHTSs was controlled by using PS spheres with different size as templates. Moreover, DHTSs was also incorporated into waterborne polyurethane (WPU) matrix to prepare WPU/DHTSs composite film as glass coating. The effect of the diameter of DHTSs on the transparency, thermal insulation and UV-shielding properties of WPU/DHTSs composite film were investigated in detail. And the results revealed that the composite film with 230 nm-sized DHTSs exhibited the optimum performance. In addition, the temperature rise rate in the chamber fitted with the glass coated by WPU/DHTSs composite film (26%) was lower than that fitted with the common glass without coated by anything (48%). Therefore, the transparent coating with excellent thermal insulation and good UV-shielding properties will become a potential energy saving building glass coating.     

氧化石墨烯改性磺酸型水性聚氨酯的制备与性能研究

首先对石墨进行氧化处理制备氧化石墨(GO),然后对GO进行超声处理得到氧化石墨烯(GOs),并通过共混法制备了水性聚氨酯(WPU)/GOs复合材料。讨论了超声分散以及GOs加入量对WPU/GOs复合材料力学性能和热稳定性的影响。结果表明,经过超声分散的复合材料的力学性能比未超声分散的好;随着GOs含量的增加,复合材料的拉伸强度先增大后减小,断裂伸长率逐渐减小;加入质量分数0.50%的GOs,其WPU/GOs复合材料的热分解温度可提高44.7℃,明显提高WPU的热稳定性。     

三聚氰胺甲醛树脂包覆红磷的制备及其稳定性研究

为了提高红磷阻燃剂的稳定性,通过原位聚合方法制备三聚氰胺甲醛树脂包覆红磷。通过扫描电镜、马尔文激光粒度仪、p H测试、热重分析仪对包覆前后红磷颗粒进行表征。扫描电镜和马尔文激光粒度仪结果表明,三聚氰胺甲醛树脂可以很好地对红磷颗粒进行包覆。p H值测试显示,与未包覆红磷相比,包覆后的红磷在水下储存稳定性明显提高。热重分析结果说明,包覆红磷可以有效提高红磷的热稳定性,与未包覆红磷相比,包覆红磷的分解温度提高约57℃。同时研究了红磷粒径对包覆红磷性能的影响,包覆红磷随着红磷粒径的降低,热稳定性降低。     

Formation and Characterization of Nano‐sized RDX Particles Produced Using the RESS‐AS Process

It has been shown that nano‐sized particles of secondary explosives are less sensitive to impact and can alter the energetic performance of a propellant or explosive. In this work the Rapid Expansion of a Supercritical Solution into an Aqueous Solution (RESS‐AS) process was used to produce nano‐sized RDX (cyclo‐1,3,5‐trimethylene‐2,4,6‐trinitramine) particles. When a saturated supercritical carbon dioxide/RDX solution was expanded into neat water, RDX particles produced from the RESS‐AS process agglomerated quickly and coarsened through Ostwald ripening. However, if the pH level of the suspension was changed to 7, particles were metastably dispersed with a diameter of 30 nm. When the supercritical solution was expanded into air under the same pre‐expansion conditions using the similar RESS process, RDX particles were agglomerated and had an average size of approximately 100 nm. Another advantage of using a liquid receiving solution is the possibility for coating energetic particles with a thin layer of polymer. Dispersed particles were formed by coating the RDX particles with the water soluble polymers polyvinylpyrrolidone (PVP) or polyethylenimine (PEI) in the RESS‐AS process. Both PVP and PEI were used because they have an affinity to the RDX surface. Small and well‐dispersed particles were created for both cases with both PVP and PEI‐coated RDX particles shown to be stable for a year afterward. Several benefits are expected from these small polymer coated RDX particles such as decreased sensitivity, controlled reactivity, and enhanced compatibility with other binders for fabrication of bulk‐sized propellants and/or explosives.     

Structure-property relationships of waterborne polyurethane (WPU) in aqueous formulations

This study provides an overview of the rheological properties of aqueous polyurethanes (WPU), as the main component, or as a thickening additive in aqueous formulations. Waterborne polyurethanes (WPU) have been proposed as an environmentally friendly alternative to conventional solvent-based solutions in a variety of industrial applications such as coatings, adhesives, inks. In all these fields, the control of rheological properties became an important prerogative to determine the quality of the dispersion and its potential applicability. First, the effect of parameters such as components, particle size and content, temperature, and interactions on dispersion viscosity was reported. Then, the effect of two additives, i.e. thickeners and nanomaterials, on structure–property relationships of WPU-base systems, was described. Thickeners are rheological modifiers, commonly used to stabilize the dispersion and prevent flocculation and sedimentation of the particles, or to change the flow behavior of dispersions from Newtonian to pseudoplastic. These species can interact with water and polymer particles to create a network structure that alters the flow resistance, and thus viscosity. The use of hyperbranched aqueous polyurethane as thickening agent in WPU formulations was also presented. On the other hand, nanostructured fillers (0D/1D/2D) or a combination thereof in waterborne polyurethane led to the formation of specific microstructures that prevented the penetration of water, oxygen, and corrosive substances, also improved mechanical and thermal properties, allowing the development of high-performance WPU-based products.     

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。     

纳米硅溶胶在防反射薄膜中的应用研究

采用辐射聚合法制备了防反射涂覆液,低折材料采用含氟单体和纳米硅溶胶,涂覆液中加入了溶剂、UV固化单体、引发剂、流平剂等助剂,在三醋酸纤维素基材上用丝棒涂布制备了防反射薄膜。研究了纳米硅溶胶的分散介质、粒径大小及其用量对防反射薄膜雾度、折射率、反射率等性能的影响。     

Surface Coating of RDX with a Composite of TNT and an Energetic‐Polymer and its Safety Investigation

To improve the safety of RDX (hexogen), an energetic polymer (HP‐1) was introduced to coat RDX with 2,4,6‐trinitrotoluene (TNT) by combining the solvent–nonsolvent and the aqueous suspension‐melting method. Scanning electron microscope (SEM), transmission electron microscope (TEM), and X‐ray photoelectron spectrometry (XPS) were employed to characterize the samples, and the role of HP‐1 in the coating process was discussed. The impact sensitivity, friction sensitivity, and the thermal stability of unprocessed and coated RDX were investigated, and the explosion heat of samples was also estimated. Results indicate that HP‐1 improves the wetting ability of the liquid coating material on RDX surface and reinforces the connection between RDX and the coating material. By surface coating, the impact and friction sensitivity of RDX decrease obviously; the drop height (H₅₀) is increased from 37.2 to 58.4 cm, and the friction probability is reduced from 92 to 38%. The activation energy (E) and the self‐ignition temperature increase by 10457.38 J⋅mol⁻¹ and 1.8 K, respectively. The explosion heat is reduced merely by 0.93%.