Effects of gellant concentration on the burning and flame structure of organic gel propellant droplets

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.     

新型耐高温阻燃层压板的研制

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.     

Controllable synthesis and flame retardant properties of bunch-, chrysanthemum-, and plumy-like 4ZnO·B2O3·H2O nanostructures

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.     

Preparation and characterization of a graphite electrode containing carbon nanotubes grown in situ by flame synthesis

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.     

Effect of a novel phosphorus‐containing compound on the flame retardancy and thermal degradation of intumescent flame retardant polypropylene

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.     

红磷母粒与氢氧化镁协效阻燃高抗冲击强度聚苯乙烯研究

采用红磷母粒与氢氧化镁协效阻燃制备无卤高抗冲聚苯乙烯复合材料.利用万能试验机测试复合材料的力学性能,利用水平-垂直燃烧仪与氧指数测定仪测试复合材料的阻燃性能.结果表明,在协效阻燃剂添加分数相同时,红磷母粒与氢氧化镁的配比分数对复合材料的力学性能与阻燃性能均有影响.     

聚酰胺6/黏土纳米复合材料阻燃性能的研究进展

对聚酰胺6/黏土纳米复合材料的阻燃性能研究进展进行了综述.阐述了聚酰胺6/黏土纳米复合材料的阻燃机理,结合相关的实验结果分析了各种因素对聚酰胺6/黏土纳米复合材料阻燃性能的影响;结合聚酰胺6/黏土纳米复合材料的研究现状,展望了未来的研究趋势.     

高抗冲阻燃回收ABS的制备及其性能研究

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。     

溴系阻燃剂五溴甲苯的合成新工艺研究

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)...     

阻燃剂RDP的合成研究

以三氯氧磷、间苯二酚及苯酚为原料,合成阻燃剂间苯二酚双(二苯基磷酸酯)(RDP);考察了催化剂种类及用量、原料配比、反应温度和时间对合成反应的影响,确定了最佳的工艺条件:n(三氯氧磷)∶n(间苯二酚) ∶n(苯酚)=4.5∶1.0∶3.7,催化剂无水氯化镁用量约为间苯二酚质量的2.5％,第一步反应温度85～90℃,反应...