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961.
Effects of gellant concentration on the burning and flame structure of organic gel propellant droplets 总被引:1,自引:0,他引:1
The increasing demand for higher energy density fuels and the ever-increasing concern for their safety have propelled research in the field of gel propellants. For studying the fundamental parameters without the interference of neighbouring droplets, an isolated droplet was chosen to investigate experimentally the combustion process of gel propellants under normal gravity conditions. Phase separation of the gel propellant components leading to bubble nucleation, vapor jetting and microexplosions were found to be the main phenomenon involved during the combustion period. Experiments were comprehensively carried out to study the effect of gellant concentration on the burning rate constant as well as flame structure. The burning rate constant was found to decrease with increase in the gellant concentration. Decrease in the calorific value of the increasing gellant concentrations was proposed as one of the reasons for this variation. The flame exhibited a triple flame structure for all the cases for both radicals as well luminous flames. The horizontal and vertical flame standoff distances were observed to decrease with gellant content. Decrease in the content of the base fuel was proposed as the reason for the same. 相似文献
962.
以苯酚、甲醛为原料,在催化剂的作用下合成酚醛树脂,然后用硼酸改性得到硼酚醛(FB)树脂.采用FB树脂作为基材树脂制作玻璃布层压板,FB树脂的耐热性比普通酚醛树脂高.FB树脂层压板具有好的耐热、阻燃、机械和电气性能,其阻燃性能达到了UL-94垂直燃烧法V-0级. 相似文献
963.
Three kinds of new 4ZnO·B2O3·H2O nanostructures of bunch-, chrysanthemum-, and plumy-like morphologies have been synthesized under hydrothermal conditions at 140 °C in the presence of ethanol. The as-synthesized products were characterized by the chemical analysis, TG, XRD, FT-IR, SEM and TEM. All the synthesized 4ZnO·B2O3·H2O nanostructures consist of nanoribbons. A series of control experiments confirmed that the morphologies of the products were influenced by the reaction time, temperature, and the presence of the surfactant of PEG-300. Furthermore, the flame retardant properties of the synthesized 4ZnO·B2O3·H2O nanostructures were investigated by the thermal analysis method, demonstrating that they had the better behaviors than the non-nanostructure sample. 相似文献
964.
A crystalline flake graphite electrode (GE) was impregnated with nickel particles using direct current electrochemical deposition. The particles were used for in situ growth of carbon nanotubes (CNTs) by flame synthesis with a liquid ethanol flame. The obtained electrode was characterized by X-ray diffraction, and scanning and transmission electron microscopy. The results showed that the deposited Ni catalyst crystal face was mainly (1 1 1). CNTs with a diameter of about 40 nm were uniformly grown on the GE surface. The electrochemical performance of the CNT–GE was characterized by cyclic voltammetry using a [Fe(CN)6]3−/[Fe(CN)6]4− solution, and showed a much greater electrochemical response than that obtained using a material in which CNTs were grown by catalytic chemical vapor deposition. 相似文献
965.
A novel flame retardant, tetra(5,5‐dimethyl‐1,3‐ dioxaphosphorinanyl‐2‐oxy) neopentane (DOPNP), was synthesized successfully, and its structure was characterized by FT‐IR, 1H NMR, and 31P NMR. The thermogravimetric analysis (TGA) results demonstrate that DOPNP showed a good char‐forming ability. Its initial decomposition temperature was 236.4°C based on 1% mass loss, and its char residue was 41.2 wt % at 600°C, and 22.9 wt % at 800°C, respectively. The flame retardancy and thermal degradation behavior of novel intumescent flame‐retardant polypropylene (IFR‐PP) composites containing DOPNP were investigated using limiting oxygen index (LOI), UL‐94 test, TGA, cone calorimeter (CONE) test, and scanning electron microscopy (SEM). The results demonstrate that DOPNP effectively raised LOI value of IFR‐PP. When the loading of IFR was 30 wt %, LOI of IFR‐PP reached 31.3%, and it passed UL‐94 V‐0. TGA results show that DOPNP made the thermal decomposition of IFR‐PP take place in advance; reduced the thermal decomposition rate and raised the residual char amount. CONE results show that DOPNP could effectively decrease the heat release rate peak of IFR‐PP. A continuous and compact char layer observed from the SEM further proved the flame retardance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011. 相似文献
966.
967.
968.
利用2,4,6-三(2,4,6-三溴苯氧基)-1,3,5-三嗪(溴代三嗪)及三氧化二锑对回收丙烯腈-丁二烯-苯乙烯共聚物(ABS)进行阻燃改性,并利用ABS高胶粉对阻燃回收ABS进行增韧改性。研究表明:当溴锑的物质量之比为3 1∶时,阻燃效率最高,并且随着溴代三嗪及三氧化二锑总用量的增加,阻燃回收ABS的氧指数呈上升趋势而拉伸强度、弯曲强度、冲击强度均呈下降趋势。而随着ABS高胶粉用量的增加,冲击强度呈上升趋势,而拉伸强度、弯曲强度及氧指数呈较小幅度的下降趋势。 相似文献
969.
溴系阻燃剂五溴甲苯的合成新工艺研究 总被引:1,自引:0,他引:1
由甲苯经溴化制得五溴甲苯,重点考察了催化剂掺杂质量比、催化剂的用量、原料配比、反应时间等工艺参数对合成产物的影响.实验结果表明,m(Bu2SnCl2):m(AlCl3)=1:1作为复合催化剂,对合成五溴甲苯有着良好的催化活性,当m(复合催化剂):m(甲苯)=0.05,n(甲苯):n(溴)=1:7.5,n(溶剂CCl4)... 相似文献
970.