Combustion Characteristics of High Burn Rate Azide Polymer Propellant

The combustion characteristics of high burn rate azide polymer composite propellant were examined by using a chimney type strand burner, a Ø 80 mm × 140 mm small rocket motor and a L/D = 16 of Ø 70 mm heavy-wall rocket motor. The propellant, BAMO/NMMO copolymer was used as a fuel binder and AP as an oxidizer, burned approximately 29 mm/s at a pressure range of 7 MPa to 20 MPa with a plateau-mesa burning behavior. However, the pressure exponent rapidly increased at above the pressure of 20 MPa and was 0.52 between 20 MPa and 25 MPa. The low pressure exponent and high burn rate of the azide polymer propellant are suitable to the short burn time at the maximum expected operating pressure range of 15 MPa to 20 MPa. The high L/D heavywall rocket motor with volumeric mass fraction of 83% showed stable combustion without any pressure oscillation and severe erosive burning. The average burn rate in the high L/D motor was 10% larger than that estimated from the strand data. The theoretically calculated pressure-vs-time and thrust-vs-time curves were well consistent with the measured data. α = 20 and β = 180 for the Lenoir-Robillard equation were used to estimate the burn rate.     

Synthesis and Characterization of Glycidyl Azide Polymer with Enhanced Azide Content

ABSTRACT

The present study reports the preparation of glycidyl azide polymer with enhanced azide content. This process involves the cationic ring-opening polymerization of epichlorohydrin (ECH) using borontrifluoride etherate (BF₃-etherate) and 2,2-bis(bromomethyl)1,3-propane diol (BMPD) as initiator and co-initiators, respectively, followed by subsequent azidation of the product. For both the products, poly(epichlorohydrin)s (PECHs) and glycidyl azide polymers (GAPs) the substituted 1,3-propane diol units were characterized by spectroscopic as well as thermal analysis. Vapor pressure osmometer studies indicated that as the diol concentration increased in the polymerization the formed PECH molecular weight decreased. The spectral analysis indicates the presence of corresponding diol units in their polymeric chains. The differential scanning calorimetry and elemental analysis of the GAPs developed in this investigation indicated the presence of higher azide content in the polymer.     

Impact Sensitivity of Azide Polymer Composite Propellants

Effects of azide polymers on the sensitivities and fragmentation mechanism were studied in this paper. Only fragmentation was observed at lower impact velocity, up to 172 m/s, even with an one-kilogram impactor. Most of the propellants showed linear relationship between an impact velocity and a fragmented fraction. The critical impact velocity, V_CR, depended on the amount of the binder but not on the chemical structures. The propellants which had no particle oxidizers showed high V_CR and their cracks were hard to grow into a piece of fragment. Nitramine-binder matrix dewetting caused by the deformation of the propellant was supposed to terminate the crack propagation and to damp the impact energy at a higher impact velocity. In AP-based propellants impact velocity dominated the initiation mechanism and impact energy did not control the ranking of the reaction. The friction energy played a more important role in the initiation than did the impact energy. There was no difference in the sensitivity to the card gap test between the azide polymer and HTPB binder.     

端乙酸酯基GAP的合成与性能研究

以1,4-丁二醇为引发剂,三氟化硼乙醚络合物为催化剂,使环氧氯丙烷发生开环聚合制得环氧氯丙烷均聚物（PECH）,PECH经叠氮化形成端羟基叠氮基缩水甘油醚聚合物（GAP）,然后再以1-甲基眯唑为催化剂,用乙酸酐将GAP酯化成端乙酸酯基GAP（ETGAP）。用FT—IR、DSC等方法研究了ETGAP的结构和性能。ETGAP的玻璃化转变温度为-65．36℃,热分解温度为251．02℃,黏度小,可用作含能增型剂。     

GAP增塑剂合成研究进展

概述聚叠氮缩水甘油醚(GAP)增塑剂的合成方法、合成路线及新进展,重点介绍了端羟基GAP、端叠氮基GAP、端酯基GAP和端酯基端叠氮基GAP增塑剂的合成。     

ATGAP的合成与性能

以1,4-丁二醇为引发剂,三氟化硼乙醚络合物为催化剂,环氧氯丙烷发生开环聚合得到环氧氯丙烷均聚物(PECH).采用磺酸酯法,首先PECH与对甲苯磺酰氯在吡啶介质中反应形成端磺酸酯基氯化聚醚中间体(TsPECH),然后中间体经叠氮化作用形成端基为叠氮基的叠氮缩水甘油醚聚合物(ATGAP).用红外、核磁、碳谱研究化合物的结构.结果表明,所得产物是目标聚合物,ATGAP的玻璃化转变温度为-73 ℃,热分解温度为252.7 ℃,黏度小,可以作为含能增塑剂使用.     

端叠氮基聚叠氮缩水甘油醚的合成与热性能

以不同多元醇为起始剂,环氧氯丙烷经阳离子开环聚合得到不同结构的端羟基聚环氧氯丙烷(PECH-OH),将其端羟基进行磺酰化改性得到端磺酸酯基聚环氧氯丙烷(PECH-OTS),随后的叠氮化反应中叠氮基同时取代PECH-OTS的端磺酸酯基和侧基中的氯得到目标产物。用IR、GPC、TG和DSC对不同结构的GAPA进行了表征。结果表明,GAPA-2、GAPA-3和GAPA-4的数均相对分子质量分别为810、830和1190,玻璃化转变温度分别为-67.5、-63.8和-58.6℃,端叠氮基聚叠氮缩水甘油醚(GAPA)的热分解可分为相对独立的叠氮基热分解(250℃)和聚醚主链热分解。     

聚叠氮缩水甘油醚的合成与改性研究进展

聚叠氮缩水甘油醚(GAP)是国内外重点研究的含能粘合剂之一。该文综述了GAP的合成研究进展,重点介绍了高相对分子质量GAP、支化GAP和等规GAP的合成。针对GAP反应活性低的特点,介绍了GAP的多种端基改性方法。GAP的无规、嵌段共聚物改善了GAP粘合剂的性能,GAP与其他粘合剂的互穿及共混,为GAP在推进剂中的应用提供了广阔前景。引用文献37篇。     

叠氮硝酸酯对硝胺改性双基推进剂燃烧性能的影响

研究了一种叠氮硝酸酯PDADN对硝胺改性双基推进剂燃烧性能的影响。结果表明添加叠氨酸酯是一种提高硝胺改性双基推进剂燃速与能量的切实可行途径。     

Combustion Aspects of Sodium Azide and its mixtures with potassium perchlorate and burning catalysts

Linear burning rate, thermal aualysis, temperature profile, flame structure and cryogenic burnability for the mixtures of sodium azide (SA) of different particle sizes (3.5 μm, 22 μm, and 67 μm), potassium perchlorate (KP) and with or without three kinds of burning catalysts (GeO₂, Er₂O₃, and Y₂O₃) have been investigated. The linear burning rates increase with the KP content up to 33Wt% for similar SA particle size. The temperature-time histories in the vicinity of burning surface were obtained with 20 μm Type K thermocouple embedded in a Strand. The burning surface temperaturres of neat SA and of the SA/KP mixtures are nearly 350°C and 350°C ∼ 550°C, respectively, while the existence of the decomposition surface at 250 °C and condensed layer was suggested with SA/KP mixtures. In visual observation for the flame structure, the front of luminous flame zone appers to be in contact with the condensed phase surface. For example, however, the temperature profile suggests that there exists finitc distance from decomposition surface to flame front in the order of 0.05 mm ∼ 0.1 mm at 1 MPa for SA/KP = 80/20. The differential thermal analysis indicates that the tested catalysts have retarding effect on SA combustion, but a positive effect on neat KP decomposition in spite of being impotent for the burning rate increase of the SA/KP mixture. It was also found that SA strands containing appropatiae fractions of KP can hurn even in liquid nitrogen.     

Microheterogeneous Mechanism of Gasless Combustion

A model for gasless combustion is considered, based on the assumption that the medium consists of reaction cells whose exchange with heat proceeds much more slowly than heat transfer in each cell. For various reaction rates and kinetic laws, temperature dependences of the burning rate are calculated and compared with available experimental data. Thermal and concentration structures of the combustion wave are revealed. Existence domains and stability boundaries of microheterogeneous and quasihomogeneous modes of gasless combustion are established, depending on the preexponent and activation energy of the chemical reaction. The effect of abrupt acceleration of the reaction at a critical point (for instance, at a phasetransition point) on the combustion pattern is analyzed.     

聚合物典型燃烧测试方法及其比较

文章阐述了聚合物阻燃理论的基本原理.对用于评价燃烧性能的主要阻燃特性和极限氧指数法、UL 94法、锥形量热仪法这三种典型测试方法做了介绍和比较.最后,展望了未来发展趋势.     

Compounding of Glycidyl Azide Polymer with Nitrocellulose and its Influence on the Properties of Propellants

Currently formulated propellants comprise RDX and polymeric binders, such as hydroxy‐terminated polybutadiene (HTPB) and cellulose‐acetate butyrate (CAB) as well as the energetic substances glycidyl azide polymer (GAP) and nitrocellulose (NC). Propellants based on GAP are often brittle if they are formulated with a high content of cyclotrimethylene trinitramine (RDX) and due to the usually insufficient mechanical properties of GAP. On the other hand formulations based on RDX and NC may exceed the tolerable burning temperature with increasing RDX concentration. Therefore, in this study propellants with a high force and with relatively low burning temperature has been formulated by using a compound of NC and GAP as energetic binder. According to thermodynamic calculations GAP/NC composite propellants can be formulated with up to 15 percent more specific energy than seminitramines at the same burning temperature. By choosing appropriate polymerization conditions chemical stable compositions can be produced. ARC experiments give evidence that at temperatures from 120°C to 160°C the binder decomposes similar to NC. At higher temperatures the behaviour switches from NC type to GAP type decomposition. In comparison to GAP bound propellants the compressive strength of propellants bound by the GAP/NC compound can be significantly increased by up to 420 percent at room temperature. Although the examined seminitramine propellants bound with NC show a compressive strength which is about 10 percent higher at room temperature, the GAP/NC compositions are quite superior at elevated temperature.     

Reduction of the Combustion Mechanism of Hydrogen

A set of programs for thermodynamic analysis of a complex chemical reaction is developed. Based on the maximum complete scheme of hydrogen combustion, reduced mechanisms that describe available experimental data are found.     

火烧油层化学机理研究

研究火烧油层化学机理,是为了改善火烧油层燃烧性能参数,而认识火烧油层技术最直接、最有效的研究手段之一是物理模拟实验,所以,借助火烧油层物理模拟实验来开展火烧油层化学机理及其改善方法研究是行之有效的。火烧油层复杂的化学机理使得火驱工艺过程的复杂性大大增加,对火烧油层化学反应的定性及定量分析是完善和发展火驱采油技术的基本途径。     

NEPE推进剂燃烧机理研究

应用微热电偶测温和燃烧火焰单幅照相技术测得 NEPE推进剂在稳态燃烧条件下的燃烧波温度分布及火焰结构 ,研究了该推进剂中主要组分对燃烧性能的影响 ,同时利用扫描电镜 -能谱仪观测了熄火表面形貌和元素分布规律。经过综合分析 ,提出了 NEPE推进剂的燃烧过程 ,为该类推进剂燃烧物理模型的建立奠定了基础     

Azide Reactive Dyes

Reactive dyes containing a sulphonylazide group can undergo fixation on nylon substrates by two different mechanisms. Under aqueous dyeing conditions, at or below 120d? C, the free amino end-groups of the polymer attack the sulphonylazide group with displacement of azide ion, and results in attachment of the dye to the substrate by a sulphonamide linkage. In contrast, if the dyed substrate is subjected to dry heat fixation at 170d? C, the azide group decomposes to a sulphonylnitrene species which undergoes insertion into C-H bonds of the polymer. The dye is again attached by a sulphonamide bridge, but in this case the amount of dye that can be fixed is independent of the amino end-group content of the polymer.     

聚合物基PTC复合材料导电机理探讨

以导电炭黑填充聚乙烯复合体系为研究对象,阐述了炭黑粒子在体系中的分布状态及导电逾渗链形成过程,并在此基础上探讨了复合体系的导电机理。     

聚合物电致发光器件老化机理的研究

文章比较了聚合物pheny1-substitutedpoly[p-pheny1eneviny1ene]derivative(P-PPV)绿光电致发光器件老化前后的I-V特性曲线及亮度曲线,详细地分析了黑斑产生的可能原因。对提高聚合物电致发光器件的稳定性具有一定的指导意义。