Safety assessment studies of a damaged high-energy solid propellant

Abstract

This article presents a study of the effects of damage on the thermal decomposition, combustion and deflagration-to-detonation transition (DDT) of the NEPE (Nitrate Ester Plasticized Polyether) propellant in order to assess its safety. The study includes: (1) to induce damage into the propellants by means of a large-scale drop-weight apparatus; (2) to observe microstructural variations of the propellant with a scanning electron microscope (SEM); (3) to investigate thermal decomposition tests; (4) to carry out closed-bomb tests and (5) to perform DDT tests. The NEPE propellant is found to be a viscoelastic material. The matrices of damaged samples are severely degraded, but the particles are not. The results of the thermal decomposition tests, closed-bomb tests and DDT tests show that the microstructural damage in the propellant has some marked effects on its thermal decomposition rate, bum rate and transition rate from deflagration to detonation. It is shown that the impact damage strongly influences on safety properties of the NEPE propellant.     

固体香精组成的剖析

采用红外及色—红联用技术分析固体香精组成，用面积归一法定量，方法简便快速，重复性良好。     

Characterization and Identification of Petroleum Hydrocarbons and Biomarkers by GC-FTIR and GC-MS

Abstract

Identification of petroleum hydrocarbons from crude and distilled oils by GC-MS is well known. The distilled crude and oils contain specific group of hydrocarbons are known as biomarkers bearing the information of their geographical source or origin and the geological past. These are diamondoids (adamantanes, diadamantanes, terpanes, steranes, sesquiterpanes, hopanes, norhopanes, etc.). The present article describes the identification of hydrocarbons using their IR spectra in the molecular fingerprinting region where every molecule shows its unique and characteristic individual vibrational frequencies. GC-FTIR spectrum of each of the individual components present in distilled oils was identified by proper standard library matching with the spectrum of the individual component. The GC-MS profiles of the biomarkers of different light and middle distilled fine products of samples from three leading oil companies, namely Indian Oil Corporation (IOC), Indo-Burma Petroleum (IBP), and Bharat Petroleum Corporation (BPC), differ from each other, indicating the variation of the sources of the crudes used by the companies. But nothing specific can be said about the origin of crudes from this limited data.     

Pyrolysis characteristics of a North Korean oil shale

Pyrolysis characteristics of a North Korean oil shale and its pyrolysates were investigated in this paper. The pyrolysis experiments were conducted below 600 °C at a heating rate of 10, 15, 20 and 25 °C/min, respectively. The kinetics data were calculated using both integral and differential methods with the assumption of first order kinetics. The results show that the averaged oil content of the North Korean oil shale is about 12.1 wt% and its heat value is 13,400 kJ/kg. The oil yields at different retorting temperatures show that the higher the retorting temperature the greater the oil and retorting gas yields. The optimal retorting temperature for the North Korean oil shale is about 500 oC. The properties of the North Korean shale oil including density, viscosity, flash point and freezing point are found to be relatively low compared with those of shale oil from FuShun, China. The gasoline fraction, diesel fraction and heavy oil fraction account for 11.5 wt%, 41.5 wt% and 47 wt%, respectively. The major pyrolysis gases are CH4(the most abundant), H2, CO2, H2 S, CO, and C2-C5 hydrocarbons. The heat value of retorting gas is more than 900 kJ/mol, and the retorting gas has high sulfur content.     

岩石热解分析中离子化干扰对热解参数的影响

在岩石热解分析中当岩样碱金属和碱土金属离子含量较高时,经常发生离子化干扰的影响。在实验分析的基础上,详细探讨了发生离子化干扰的原因;并从中找到了一个简便易行的消除离子化干扰方法指出了消除离子化干扰后如何确定岩石热解参数的方法。     

Chemical characterization of plasma-treated propellant samples

Abstract

The morphological and chemical characterization of M30 propellant grains recovered after conventional or plasma ignition in interrupted closed bomb experiments has been performed. The capillary material used during plasma ignition was either polyethylene (PE) or polyethylene terephthalate (Mylar). Propellants were extinguished at pressures between 35 and 100 MPa. The samples are of interest due to previous reports of apparent burning rate augmentation with plasma ignition of M30, compared to conventional ignition, in non-interrupted closed bomb experiments [1]. Birk [2] has reported that burning rate augmentation appears to occur during the plasma event, but there was no evidence for post-plasma augmentation. Birk has also analyzed vivacity curves from plasmaignited M30 and the data indicated that the grains appear to burn regressively, suggesting an increase in surface area was generated beyond that expected from normal grain burning [2]. In the current work, differences between extinguished grains from conventional and plasma ignition were primarily physical or morphological in nature. For the extinguished grains from PE plasma ignition there appeared to be a stripping of NQ crystals in the perforations. Along the outer surfaces of the grain ignited with plasma, hot embedded particles and increased surface area were observed, and the melt layer was immeasurably thin. Although extensive chemical characterization has been performed, there appears to be very little chemical difference between the burned surfaces of the plasma and conventionally ignited samples. The SEM analysis of the perforations showed that NQ depletion in the perforations was most evident at the lowest blowout pressure used (35 MPa) and seemed to diminish at higher pressure, apparently becoming obscured by “normal” burning processes. Thus, it appears that plasma-propellant interactions and associated effects occur only very early during ignition. This is consistent with the fact that few differences in the chemical composition are observed for plasma and conventionally ignited samples. A depletion of NQ in the perforations may contribute to a true burning rate augmentation through chemical reactions. However, a true chemical burning rate augmentation as the only mechanism for the M30 non-interrupted behavior would not be consistent with regressive burning.     

等温相继热解气相色谱法研究聚丙烯的热解

采用等温相继热解气相色谱法研究了聚丙烯的热解动力学,结果显示,聚丙烯的热解反应为动力学一级反应,Ｃ３～Ｃ４（气体部分）、Ｃ５～Ｃ１１（汽油馏份）、Ｃ１２～Ｃ２０（柴油馏份）、Ｃ２１～Ｃ３０（重油馏份）及各组份的生成反应为平行一级反应。计算了各组份生成反应的ｋ、Ｅ、Ａ值;考察了冷却剂对分离效果的影响,开发了聚丙烯的热解动力学模型,探讨了此研究对废聚丙烯油化工艺的指导作用。     

New Catalysts of Hydrocarbon Pyrolysis

Lower olefins - ethylene and propylene - occupy a leading position in the feedstock base of domestic and foreign petrochemistry. Thermal pyrolysis of hydrocarbons in tube furnaces, which ensures the almost maximum yield of target products, is the basic production process. This is due to continuous improvement of the basic equipment in the process units. In pyrolysis furnace block structures, it was directed toward making the process conditions more severe to attain the maximum yield of target products.__________Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 41 – 43, March – April, 2005.     

短链二烷基多硫的热裂解

以90～120℃石油醚为模拟轻烃,以二甲基二硫、二乙基二硫、二叔丁基二硫、二甲基三硫和二乙基三硫为代表性二烷基多硫,在高压反应釜内进行轻烃中微量多硫的热裂解反应,考察反应条件对二烷基多硫的热裂解反应的影响,并采用气相色谱测定二烷基多硫的热裂解产物.结果表明:反应温度、反应压力显著影响短链二烷基多硫的热裂解反应;二烷基多...     

Development of high burn rate azide polymer propellant

Abstract

The combustion characteristics of high burn rate azide polymer composite propellant were examined by using ? 70 mm BMI composite rocket motor of L/D = 16. Azide polymer propellants have much higher specific impulse than HTPB propellant at below the AP content of 85%. AP/B/N propellants showed a plateau-mesa burning at a pressure range between 7 MPa and 15 MPa with a burn rate of approximately 28 mm/s. Very fine AP, however, diminished this favorable combustion characteristics. The AP/B/N also had excellent mechanical properties at an operational temperature range to enable the case bonded. The BMI motors burned stably and showed an excellent performance. The thickness of the insulation at the aft closure, 5.5 mm including a stress relief boot, was good enough.     

Catalytic activity of nano-sized CuO on AP-CMDB propellant

ABSTRACT

In this work, nano-sized CuO prepared by mechanical grinding method was applied to the AP-CMDB propellant. The catalytic activity of nano-sized CuO on AP-CMDB propellant was investigated by thermogravimetric analysis/differential scanning calorimetric techniques. The combustion rates at atmospheric pressure of AP-CMDB propellant modified by nano-sized CuO were measured by strand burner method. The experimental results show enhancements on the thermal decomposition and combustion of AP-CMDB propellant in the presence of nano-sized CuO. Compared with blank propellant, the thermal decomposition temperature of AP-CMDB propellant shifts downward. Simultaneously, the combustion rate of AP-CMDB propellant at atmospheric pressure increases by about 22.2%. Encouragingly, the catalytic activity of nano-sized CuO on AP-CMDB propellant is superior to that of the bulk CuO, which leads to a potential application of nano-sized CuO in the AP-CMDB propellant.     

Evaluation studies on partial replacement of RDX by spherical NTO in HTPB-based insensitive sheet explosive formulation

ABSTRACT

Hydroxyl terminated polybutadiene (HTPB)-based sheet explosive incorporating spherical 3-nitro-1,2,4-triazol-5-one (NTO) as a partial replacement of 1,3,5-trinitro-1,3,5-triazinane (RDX) was investigated. The effect of incorporation of NTO on mechanical properties, sensitivity behavior, and velocity of detonation (VOD) was studied in comparison with a sheet explosive formulation containing 82 wt% RDX, both based on an HTPB-binder system. The replacement of 22 wt% of RDX by spherical NTO resulted in reduced vulnerability to shock as well as impact stimuli. The data demonstrated that the NTO-added formulation was found to be higher shock insensitive compared to the RDX-only formulation. However, ~5% decrease in VOD was observed on incorporation of NTO. Further, the sheet explosive formulations were found insensitive toward friction up to 360 N. Also, molecular dynamics simulations were performed to predict the elastic constants of RDX and NTO and the results revealed that the predicted trend correlated with the experimentally obtained mechanical properties of the formulations.     

Pyrolysis Mechanism of a Cyclotriphosphazene-Based Flame-Retardant Epoxy Resin by ReaxFF Molecular Dynamics

Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs) via their influence on the pyrolysis process. In this work, the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP) incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method. The pyrolysis fragments, initial reaction pathways, and main products were identified for the EP and EP/HMPOP composites. The activation energies were deriv...     

Hydrolysis of the energetic materials present in a composite modified double base solid rocket propellant

Abstract

The aqueous hydrolysis of the nitroglycerin (NG), nitrocellulose (NC), and HMX present in CYH, a composite modified double base solid propellant, was successfully performed using either sodium hydroxide (NaOH) or ammonia (NH₃) as hydrolyzing agents. The rate of hydrolysis was faster for NaOH compared to NH₃. For both hydrolysis agents the rate of hydrolysis of NG was the fastest, followed by NC and then HMX. It was determined that 4 parts of NaOH were required to hydrolyze the energetic ingredients in 10 parts of CYH. A similar determination was not made for NH₃.

The original set of experiments were done on a small scale (0.030-10 grams of propellant) with laboratory glassware. Later experiments involved the hydrolysis of larger amounts of propellant (200 grams), again using laboratory glassware. The last set of experiments were accomplished with a small scale glass reactor (4 liters) with up to 900 grams of propellant per run. In addition, exhaustive chemical analysis yielded useful information about the hydrolysis products. The combined data was used to design a reactor for the hydrolysis of 4,000 Ibs of CYH propellant.