NGEC基改性双基推进剂的制备及性能

为改善双基推进剂的低温力学性能,将纤维素通过碱化、醚化转变成纤维素甘油醚,再经硝化得到不同醚化度、酯化度的NGEC。测定和分析了NGEC基和NC基双基推进剂的力学和能量特性,电镜扫描观察了拉伸膜断截面喷金后的端面形貌。结果表明,NGEC双基推进剂的力学性能、爆热和比容均高于NC双基推进剂,制品内部结构均匀,抗压强度(+50℃)σm≥11.0M Pa,延伸率(25℃)εm≥40%,比冲达到2 218.1N.s.kg-1。     

NEPE推进剂老化过程中结构与力学性能的关系

为考察NEPE推进剂的老化特性,在60,65,70和75℃老化了推进剂样品,研究了其在常温时的抗拉强度σm,初始模量E0与黏合剂母体凝胶质量分数ω、化学交联密度υe、物理交联密度υp之间的关系.用动态热机械分析仪(DMA)测试了多个频率下老化样品的损耗因子tanδ、损耗模量半高峰宽D h/2.结果表明,高温加速老化过程中NEPE推进剂样品σm和E0下降的原因是推进剂黏合剂母体结构的ω,υe 和υp下降.NEPE推进剂降解和解聚由黏合剂母体结构变化引起.     

高强度、高燃速丁羟推进剂配方工艺研究

对高不挥发物质量分数、高强度、高燃速丁羟推进剂进行了配方研究。采用了HTPB(端羟基聚丁二烯)、TDI(甲苯二异氰酸酯)黏合剂体系及STR增强剂的固化网络,选用SX-1助剂以改善工艺性能,通过优化AP级配、调节混合工艺程序等方法,使推进剂具有不挥发物质量分数88%、密度1.82g/cm3、20℃抗拉强度σm3MPa、65℃抗拉强度σm≥2.3MPa,燃速35mm/s的良好性能,并具有药浆初始黏度低,工艺流动流平性好的特点。     

室温固化催化剂的研制和在固体推进剂中的应用

研制了 3种有机金属化合物TEPB p、TEPB m和TEPB o,均为白色结晶 ,纯度 >99.0 %。通过热分析方法、推进剂配方工艺研究与性能测试 ,探讨了它们对NEPE和丁羟固体推进剂固化反应的催化作用。结果表明 ,其催化活性高 ,能降低固化反应温度 ,能使推进剂药浆在室温 (35℃或 35～ 4 0℃ )保温 7～ 8d完全固化 ,并使获得的推进剂具有良好力学性能 ,因而它们可用作室温固化催化剂。     

低铝粉含量的HMX/HTPB推进剂研究

对低铝粉含量的HMX/HTPB推进剂进行了配方研究。为获得少烟、高密度、高模量、高燃速、低压强指数的优良的综合性能,配方调试以铝粉质量分数<10%,用HMX替代部分AP来达到少烟目的;以HTPB/TDI/MAPO/STR黏合剂体系来获取高模量;通过AP级配调节,燃速催化剂的选择等方法,使推进剂具有不挥发物质量分数≥88.5%、20℃下密度≥1.78 g/cm3、σm≥3.1 MPa,燃速≥40 mm/s的良好性能,并具有药浆初始黏度低,流动、流平性好的优点。HTPB/AP/Al/HMX四组元推进剂经BSFΦ127标准发动机地面试车,内弹道p–t曲线在压强30 MPa以下,燃烧稳定;推进剂燃烧未急升导致压强异常现象。研制成的药柱经发动机地面试验可知混合比冲高达2 456.7 N·s/kg。     

某高燃速丁羟推进剂配方研究

对高燃速、力学性能优良的丁羟推进剂进行了配方研究。该配方采用了HT-PB（端羟基聚丁二烯）、TDI（甲苯二异氰酸酯）粘合剂体系,选用101/102/103/106助剂以改善工艺性能和力学性能,通过优化AP工艺方法,使该丁羟推进剂具有固体含量为86%、密度≥1.78g/cm3、在50℃抗拉强度≥0.5MPa基础上,20℃...     

高固体含量高强度丁羟推进剂工艺调节技术研究

阐述不同燃速的高固体含量高强度丁羟推进剂的工艺调节技术,研制出了中低燃速、中燃速和高燃速3种燃速范围,固体质量分数≥90%、20℃最大抗拉强度≥2.5MPa的丁羟推进剂配方,其工艺性能良好,并成功应用于高性能固体火箭发动机。     

某型号导弹固体发动机贮存使用寿命研究

利用推进剂方坯加速老化试验对某型号导弹固体发动机进行了推进剂贮存寿命预估。通过对试验数据的分析,建立了固体推进剂老化速率的动力学方程,预估了固体推进剂的贮存寿命。结果表明,推进剂在25℃下贮存10 a后最大伸长率(εm)为31.57%,与起始εm比较,仅下降了27%,满足发动机安全使用要求。     

硝酸酯聚醚推进剂的能量特性

采用凝胶色谱(GPC)、DSC、密度计等方法研究了端羟基聚3-硝酸酯甲基-3-甲基氧丁环(PNMMO)的分子结构、理化和安全等性能,其密度(ρ)、生成焓(ΔHf)、玻璃化温度(Tg)和摩擦/撞击感度(H50)分别为1.26g/cm3、-1933.74kJ/kg、-30℃、0%和109.6cm,PNMMO弹性体的最大抗拉强度(σm)和最大延伸率(εm)分别为3.54～7.72MPa和253%～279%.用推进剂能量计算程序计算了PNMMO推进剂与NEPE和GAP推进剂的理论比冲.结果表明,PNMMO推进剂的理论比冲(6.86MPa)比NEPE推进剂的值68～140N·s·kg-1,比GAP推进剂的理论比冲低3～7N·s·kg-1.     

提高溶剂压伸复合改性双基推进剂力学性能研究

力学性能是推进剂在固体发动机中应用的重要参数之一,为有效提高溶剂压伸复合改性双基(CMDB)推进剂力学性能,研究了吸收药种类、溶剂比、增强材料、黏合剂相对分子质量等对推进剂力学性能的影响。结果表明,吸收药种类对推进剂低温力学性能影响较大,溶剂比对推进剂力学性能影响不明显,加入增强材料后CMDB推进剂-40℃冲击强度可达4.06 kJ/m2。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。