锆/聚叠氮缩水甘油醚复合粒子的制备、表征及静电性能

锆粉具有密度大、体积热值高、点火和燃烧性能良好的优点,是提升推进剂密度比冲的重要燃料,但由于其静电火花感度高,使用中易燃烧,在推进剂中应用存在安全隐患。为提高锆粉的抗静电性能,研究采用一种推进剂常用的聚叠氮缩水甘油醚(GAP)含能粘合剂,对锆粉进行包覆改性,获得了Zr/GAP复合粒子。研究其形态、结构、热性能和抗静电火花性能。结果表明,包覆处理可显著降低锆粉粒子的静电火花感度,50%发火能从5.13 mJ提高至24.91 mJ,并且保留了锆粉的高密度特性及良好的燃烧性能。研究成果为促进锆粉在高密度推进剂中的应用提供了技术支持。     

GAP/CL-20基混合炸药药浆的流变性

采用粘度测试技术研究了聚叠氮缩水甘油醚(GAP)/六硝基六氮杂异伍兹烷(CL-20)基混合炸药药浆的流变特性、挤注工艺温度和固化过程中温度与粘度的关系。用X射线衍射仪测试工艺温度对其混合炸药中CL-20的晶型的影响。结果表明,混合炸药药浆为假塑性流体,80℃为最佳挤注工艺温度,固化后混合炸药中的CL-20仍为ε晶型。根据药浆的化学反应流变特性,在恒温条件下采用双阿伦尼乌斯方程建立的粘度模型为ηt=447.5329exp(25.20883/T)exp[0.02922exp(7.18748/T)t]。在20,40,60,80℃时,该模型的理论预测粘度与实验结果吻和良好。     

GAP/HTPB共混粘合剂体系的力学性能研究

利用端羟基聚丁二烯(HTPB)粘合剂和端羟基叠氮聚醚(GAP)共混,以改善纯GAP粘合剂的力学性能;探讨各种固化反应条件对共混粘合剂力学性能的影响;静态拉伸测试结果显示共混胶片的确产生了协同效应,GAP与HTPB质量比11时,常温下粘合剂拉伸强度可达到3.833MPa,最大延伸率可达593%。动态热机械测试(DMA)结果显示,通过调整固化工艺条件,能够使得GAP与HTPB本不相容的两相产生反应增容,损耗因子-温度(Tanδ-T)曲线在-60.2℃附近出现单一的玻璃化温度;SEM照片更从微观形态上印证了以上两点。结果显示,HTPB与GAP共混粘合剂体系具有良好的力学性能,对GAP在复合固体推进剂中的应用具有一定的参考价值。     

基于GAP技术的校园网安全设计

本文系统地介绍了GAP技术的工作原理、功能及安全优势,分析了校园网安全存在的问题,并对存在的问题提出了基于GAP技术的解决方案。     

Progress in Computational Complexity Theory

We briefly survey a number of important recent achievements in Theoretical Computer Science (TCS), especially Computational Complexity Theory. We will discuss the PCP Theorem, its implications to inapproximability on combinatorial optimization problems; space bounded computations, especially deterministic logspace algorithm for undirected graph connectivity problem; deterministic polynomial-time primality test; lattice complexity, worst-case to average-case reductions; pseudorandomness and extractor constructions; and Valiant's new theory of holographic algorithms and reductions.     

GAP/HTPB粘合剂固化胶片力学性能研究

选用主链柔顺性好,可在推进剂中单独用作粘合剂的端羟基聚丁二烯(HTPB),通过化学共聚的方法来改善叠氮缩水甘油醚(GAP)的力学性能.反应活性对比表明,二者与异佛尔酮二异氰酸酯(IPDI)的反应速度有较大差异,进而影响粘合剂固化胶片的网络结构.实验结果表明:加入扩链剂和交联剂,所得粘合剂力学性能有较大提高,拉伸强度可达1.43MPa,延伸率为382.37%.     

Synthesis of Carbon‐Rich Hybrid Foam from GAP‐Modified Polyurethane

4,4′‐Diisocyanato diphenylmethane (MDI)‐based polyurethanes melt and start to burn at 150–200 °C. Mainly H₂O, CO₂, CO, HCN, and N₂ are formed. The new modified polyurethane shows a different pyrolysis behavior. GAP‐diol (glycidyl azide polymer), which was used as a modifying agent, is a well‐known energetic binder with a high burning velocity and a very low adiabatic flame temperature. The modified polyurethane starts to burn at approximately 190 °C because of the emitted burnable gases, but it does not melt. The PU foam shrinks slightly and a black, solid, carbon‐rich hybrid foam remains. TGA and EGA‐FTIR revealed a three‐step decomposition mechanism of pure GAP‐diol, the isocyanate‐GAP‐diol, and PU‐GAP‐diol formulations. The first decomposition step is caused by an exothermic reaction of the azido group of the GAP‐diol. This decomposition reaction is independent of the oxygen content in the atmosphere. In the range of 190–240 °C the azido group spontaneously decomposes to nitrogen and ammonia. This decomposition is assumed to take place partly via the intermediate hydrogen azide that decomposes spontaneously to nitrogen and ammonia in the range of 190–240 °C. The second decomposition step was attributed to the depolymerization of the urethane and bisubstituted urea groups. The third decomposition step in the range of 500–750 °C was attributed to the carbonization process of the polymer backbone, which yielded solid, carbon‐rich hybrid foams at 900 °C. In air, the second and the third decomposition step shifted to lower temperatures while no solid carbon hybrid foam was left. Samples of PU‐GAP‐diol, which were not heated by a temperature program but ignited by a bunsen burner, formed a similar carbon‐rich hybrid foam. It was therefore concluded that the decomposition products of the hydrogen azide, ammonia and mainly nitrogen act as an inert atmosphere. FTIR, solid‐state ¹³C‐NMR, XRD, and heat conductivity measurements revealed a high content of sp²‐hybridized, aromatic structures in the hybrid foam. The carbon‐rich foam shows a considerable hardness coupled with high temperature resistance and large specific surface area of 2.1 m²⋅g⁻¹.     

Characterization of ADN/GAP‐Based and ADN/Desmophen®‐Based Propellant Formulations and Comparison with AP Analogues

Several ADN‐based rocket propellant formulations containing different pre‐polymers (GAP diol/triol, Desmophen® 2200), curing agents (BPS, Desmodur® N100, Desmodur® N3400), plasticizers (BDNPA‐F, TMETN), and filler types (Al, HMX) have been manufactured. Propellant formulations were characterized by tensile tests, SEM analyses and DMA measurements. The study has focused on characterizations of the propellants in terms of evaluation of the strength and strain capability, investigation of the presence/absence of dewetting phenomena, compatibility issues and evaluation of the glass transition temperature. Ammonium perchlorate‐based propellant formulations have also been manufactured and analyzed in order to make comparisons. Aging was investigated using mass loss measurements.     

用GAP启动子在毕赤酵母中组成型表达重组 猕猴桃果胶甲酯酶抑制剂

目的构建组成型表达重组猕猴桃果胶甲酯酶抑制剂(kiwi pectin methylesterase inhibitor, kwPMEI)的毕赤酵母(P．pastoris)GS115工程菌株,探索碳源(葡萄糖、甘油、甲醇)对重组菌表达kwPMEI的影响,纯化kwPMEI并鉴定其对番茄果胶酶的抑制活性。方法应用PCR方法从P．pastoris GS115染色体中扩增了三磷酸甘油醛脱氢酶启动子(pGAP),以其取代诱导型表达载体pPIC9K-kwPMEI上的醇氧化酶启动子(pAOX1),构建了组成型表达载体pGAP9K-kwPMEI,并转化至GS115中。用Tricine-SDS-PAGE和Western blot分析目的蛋白表达情况,镍柱亲和层析纯化目的蛋白,并用凝胶扩散方法鉴定其抑制活性。结果重组毕赤酵母工程菌株成功组成型表达了kwPMEI,48h即达到最大表达水平,表达量约为66 mg/L。并且以甘油为碳源时kwPMEI表达量最高。成功分离纯化了kwPMEI,并经凝胶扩散方法检测表明其具有抑制活性。结论成功构建了组成型分泌表达kwPMEI的毕赤酵母菌株,为kwPMEI在果蔬汁中的进一步应用奠定了基础。     

PBAMO/GAP基ABA型ETPE的偶联法合成研究

1引言新型战术武器的发展对含能材料提出了高能、钝感和低特征信号的要求。为了适应这种要求,在研的军用粘合剂大都显示出了从惰性粘合剂到含能热固性粘合剂再到含能热塑性弹性体(ETPE)的研究趋势。ETPE是指侧基上含有—N3,—ONO2,—NO2等能量基团的热塑性弹性体,以ETPE为基的含能材料