TNT与主炸药HMX及CL-20之间的结合能对比

以ε-CL-20和β-HMX为主体炸药,分别与TNT混合,运用分子动力学(MD)方法研究和计算两者之间的结合能。结果表明,TNT与CL-20炸药的结合能要比TNT与HMX之间的结合能大,也就是TNT与CL-20之间的相容性较好。     

CL-20晶型ε→γ等温相变动力学

为研究多晶型炸药CL-20的晶相转变规律,采用原位漫反射红外光谱法研究了CL-20的晶型ε→γ等温相变动力学,通过ε-CL-20红外特征峰强度的降低表征相转变程度;采用Avrami-Erofeev方程描述了温度为160、165、170和175℃下CL-20晶型的ε→γ相转变程度-时间曲线,获得等温相变的动力学参数。结果表明,以相转变程度18%为转折点,相变过程可分为两个阶段并分别符合不同的动力学机理函数;当相转变程度为1%~18%时,其相变机理符合随机成核与生长(n=0.60~0.76)的Avrami-Erofeev方程,表观活化能(Ea)和指前因子ln(A/s~(-1))分别为150.6kJ/mol和38.1;当相转变程度为18%~94%时,其相变机理符合随机成核与生长(n=1.18~1.25)的Avrami-Erofeev方程,表观活化能(Ea)和指前因子ln(A/s~(-1))分别为289.4kJ/mol和74.7。     

六硝基六氮杂异伍兹烷四种晶型的晶体结构

测定了六硝基六氮杂异伍兹烷四种晶型（α、β、γ及ε）的单晶结构,报道了它们的晶体学参数,给出了它们的分子构型,讨论了它们的结构,并与ＨＭＸ作了比较。     

不同晶型的HMX在发射药中的应用对比

将α-HMX、β-HMX制成硝铵发射药试样,通过密闭爆发器实验,研究了硝铵发射药中不同晶型的奥克托今与燃烧性能、力学性能等的关系。结果表明,热稳定性β-HMX较α-HMX好,燃速压力指数β-HMX比α-HMX大。     

高压下CL-20拉曼光谱和红外光谱相变研究

为了更好地认识和了解CL-20晶体结构演变规律和相变行为,利用金刚石对顶砧超高压实验技术,在0~50GPa下,研究了高压下ε-CL-20的原位拉曼光谱和红外光谱。结果表明,CL-20晶体在整个加压过程中存在两个相变,第一个相变发生在4.2~7.5GPa,认为是ε相到对称性更低的γ相转变,相变产生的原因是在压强的作用下,笼环外的硝基方向发生改变,电子云密度重置导致的分子构型转变;第二个相变发生在14.2~18.9GPa,属于γ相到ζ相的晶体结构转变;卸压后,拉曼和红外光谱恢复常压状态,表明CL-20晶体在研究压强范围内的相变过程是可逆的。     

α/β-HMX混晶的机械感度和热分解性能

采用饱和溶液-冷却结晶法将β-HMX转化为α-HMX,并对α-HMX晶型进行了表征。研究了α-HMX对α-HMX和β-HMX组成混晶的机械感度和热分解性能的影响。结果表明,纯α-HMX的摩擦感度和撞击感度分别为100%和26.1cm,比纯β-HMX分别提高了14%和40.8%;纯α-HMX热分解反应的表观活化能为239.5kJ/mol,比纯β-HMX降低了4.1%。纯α-HMX的热分解反应放热量为1 063J/g,比纯β-HMX增加4.8%。随着混晶中α-HMX含量的增加,其摩擦感度和撞击感度升高,热分解反应的表观活化能降低,热分解放热量增大。     

软研磨对拜耳石热解机制的改性研究

本文采用TG-DSC、XRD及TEM等表征手段,系统研究软研磨处理对拜耳石的微结构及热解行为的影响.结果表明,软研磨减小拜耳石晶粒尺寸、引起它的晶格畸变、加速拜耳石向热稳定相的转变.相比于未经研磨的拜耳石,软研磨处理使得拜耳石热解时向热稳定相α-Al2O3开始转变及转化完成的温度分别降低了800℃和150℃,热解过程未出现θ-Al2O3过渡态,而是经历α-Al(OH)3→γ-AlOOH→γ-Al2O3→α-Al2O3晶型转变途径.也即,软研磨处理明显降低了拜耳石向稳定相α-Al2O3转变的热解温度,改变其热解途径.     

铜酞菁的晶型调整及后处理研究——酸法晶型调整

一前言铜酞菁是典型的多晶型颜料,已知有α-、β-、γ-、ε-、R-、δ-、π-、ρ-等晶型,各种晶型可以用X-衍射图谱相区别。引起铜酞菁各种晶型相互转变的方法有溶剂转变、热转变、力转变、酸法转变、升华转变等。     

含氮煤焦边缘模型氧化生成NO途径研究

通过Mayer键级预测反应过程,基于过渡态理论,在分子水平上研究了含吡啶氮的armchair煤焦边缘模型在燃烧过程中产生前驱体HCN以及直接与O2反应释放NO分子的全过程,并计算得到了每一步反应的反应能量和能垒大小.结果表明,含吡啶氮armchair煤焦模型化合物产生HCN的过程中N2—C4键和C1—C3键的Mayer键级最小,这两个键最先断裂后分离出HCN分子,该过程需要克服的能垒为451.671 kJ/mol,而用相同模型与O2直接氧化产生NO的过程中,C1—N2的Mayer键级最小,中间体M1需要克服259.81 kJ/mol的能垒形成中间体M2,中间体M2需要克服133.1 kJ/mol的能垒,并最终析出NO分子.对上述两过程进行能量对比发现,所选模型与O2直接发生异相反应释放NO气体的过程更容易发生.     

不同温度下ε-CL-20晶体感度和力学性能的分子动力学模拟计算

用分子动力学(MD)模拟计算研究了在NPT系综和不同温度(195、245、295、345、395K)下高能量密度化合物ε-CL-20的(2×3×3)超晶胞及其沿(001)晶面的模型切割。结果表明,室温下所得晶胞参数与实验值一致。随着温度的升高,引发键(N-NO2)最大键长(Lmax)递增、引发键连双原子作用能(EN-N)和内聚能密度递减,与体系热和撞击感度随温度升高而增大的实验事实相一致,表明Lmax、EN-N和内聚能密度可作含能化合物热感度和撞击感度相对大小的理论判据。获得了5个温度下ε-CL-20的力学性能,从理论上揭示了其力学性能随温度的升高而递变的规律。     

Standard Enthalpy of Formation of the Bimolecular Crystal of CL-20 with Tris-Oxadiazolo-Azepine and Its Thermal Stability

The standard enthalpies of combustion and formation of 7H-tris([1,2,5]oxadiazolo) [3,4-b:3′,4′-d:3″,4″-f]azepine, its bimolecular crystal with the γ-polymorph of CL-20, and the γ-polymorph of CL-20 have been experimentally determined. The standard enthalpies of formation of the bimolecular crystal and an equimolecular mechanical mixture of γ-CL-20 with azepine differ by less than 12.8 kJ/mol. This small difference is validated by quantum chemical calculations. It has been experimentally found that the presence of azepine in the bimolecular crystal inhibits the thermal decomposition of γ-CL-20 and increases the thermal stability of γ-CL-20 in the bimolecular crystal as compared to original γ-CL-20.     

高聚物黏结ε-HNIW混合炸药的制备及其感度

为改善原料HNIW(CL-20)的结晶品质并降低其机械感度,采用水悬浮工艺对重结晶制备的ε-CL-20进行了包覆.结果表明,原料CL-20呈多晶型,粒径不均,机械感度与PETN相当;在室温条件下,用乙酸乙酯-石油醚对原料CL-20进行重结晶可制备出晶形规整、粒径均匀的高品质ε-CL-20晶粒,撞击感度较原料略有降低;采...     

Kinetics of Solid Polymorphic Phase Transitions of CL‐20

Solid‐solid phase transitions of the CL‐20 polymorphs ε→γ, α→γ, and β→γ were studied isothermally at ambient pressure by transmission FT‐IR spectroscopy and analyzed by multivariate regression. Activation energies as function of the extent of conversion were obtained using the model‐free isoconversional method. The apparent activation energies for all three solid phase transformations were about 210 kJ/mol at 5% conversion, and compared well with the calculated lattice energies. The apparent activation energies increased to a maximum of about 400 kJ/mol at 40%, 80% and 60% conversion for ε→γ, α→γ, and β→γ, respectively, and then decreased. The mechanisms of the phase transitions of CL‐20 appear to be quite complex. Comparisons are made with the phase transitions of HMX.     

Evidence for a High‐Pressure Phase Transition of ε‐2,4,6,8,10,12‐Hexanitrohexaazaisowurtzitane (CL‐20) Using Vibrational Spectroscopy

The high‐pressure response of ε‐2,4,6,8,10,12‐hexanitrohexaazaisowurtizane (CL‐20) has been examined to 27 GPa in diamond anvil cells using vibrational spectroscopy. The results reveal evidence of an ε→γ pressure‐induced phase transition between 4.1 and 6.4 GPa and suggest the existence of a γ→ζ transition near 18.7 GPa. Several Raman and infrared frequencies were found to decrease in intensity as the phase boundaries are approached. An anomalous intensity increase was noted in the C N C infrared mode that is believed to result from an increase in the Raman cross‐section due to a stronger interlayer coupling under pressure.     

The technological importance of the crystallographic and surface properties of copper phthalocyanine pigments

New and previously reported results are combined to emphasise the importance of fundamental crystallographic and surface chemical properties on the technology of copper phthalocyanine pigments. Particular attention is paid to undesirable aggregation of pigment crystals and to the changes in aggregate structure and crystal phase which occur during ageing. The two most commercially significant forms of copper phthalocyanine are the α- and β-polymorphs. The crystals of both consist of parallel molecular stacks. In β-phase crystals, the coordinate bonding between adjacent molecules within the stacks promotes crystal growth in the direction of the stacks, producing commonly observed rod-shaped crystals. Moreover, the molecular stacks of the β-phase, being interlocked, are not readily distorted. In contrast, the distortion of lattice planes in the α-phase can accommodate mismatch between contiguous crystals, and promote their fusion into strongly coherent aggregates. Although the strength of aggregation is thus influenced by the crystal lattice, the geometric structure of aggregates is largely determined by crystal shape, brick-shaped crystals being more prone to aggregation than rod-shaped crystals. Aggregates of brick-shaped crystals are porous, and solvent molecules can penetrate some way into their internal structure. Ageing may then occur. Changes in crystal phase and aggregate structure are discussed at some length. New evidence is presented for the existence of an intermediate metastable state in the α-→β-phase transformation induced by solvents. The β-→α-phase change induced by mechanical grinding is shown to start at the surface of β-phase crystals, and then to extend gradually throughout their bulk. Examples are given of different kinds of ageing of aggregate structures. Ageing of aggregates of α-phase crystals in liquid toluene involves not only Ostwald ripening and a transformation to the β-phase, but also crystal fusion (as occurs during ageing in toluene vapour). In liquid n-propanol, on the other hand, the aggregates are converted to highly consolidated structures.     

Influence de la structure sur les propriétés mécaniques dynamiques de quelques polytéréphtalates de polyméthylèneglycol. Relaxations β et γ

The influence of structure, cristallinity and orientation on the β- and γ-relaxation mechanisms of several poly(α,ω-alkandiolterephthalates) has been investigated. The γ-relaxation consists of two main components involving molecular motions in the amorphous phase, and motions of CH₂ groups (glycolic residue) in the gauche or trans form. A third component involves movements of bigger groups. The β-relaxation at low frequencies can be compared with the dilatometric glass transition.     

Molecular dynamics simulation for fluoropolymers applied in ε-CL-20-based explosive

Herein, in order to design the formulation of fluoropolymer bonded explosives, common fluoropolymers were selected and added to the high energy density compound hexanitrohexaazaisowurtzitane (ε-CL-20). Molecular dynamics simulations were carried out on fluoropolymers (F2603, F2311, F2314, F2426, and PTFE) and fluoropolymers bonded ε-CL-20. Glass transition temperature (Tg) of fluoropolymers were calculated. Besides, the mechanical properties and physical compatibilities of ε-CL-20 based polymer bonded explosives were predicted. The calculated results show that the order of Tg of fluoropolymers is: PTFE > F2314 > F2311 > F2462 ≈ F2603 and Tg of F2603 increases as the degree of polymerization increases. The binding energy for fluoropolymers with ε-CL-20 is in the following order: ε-CL-20/F2462 > ε-CL-20/F2603 > ε-CL-20/F2314 > ε-CL-20/F2311. All fluoropolymers interact with ε-CL-20 mainly in vdW force. The order of tensile modulues is: ε-CL-20 > ε-CL-20/F2314 > ε-CL-20/F2311 > ε-CL-20/F2462 > ε-CL-20/F2603, the orders of Poisson’s ration (γ) and the quotient bulk modulus (K)/shear modulus (G) are opposite.