HTPB推进剂自然贮存与高温加速老化力学性能研究

研究了自然贮存和70、60、50℃加速老化下HTPB推进剂的力学性能变化规律。结果表明,2种条件下HTPB推进剂老化规律相同,表现为强度升高、伸长率降低。以最大伸长率为表征参量,结合自然贮存试验结果,得到HTPB推进剂老化性能与温度、时间的关系。     

湿热条件下复合固体推进剂老化特性研究

为研究HTPB(端羟基聚丁二烯)、NEPE(硝酸酯增塑聚醚)2种复合固体推进剂在湿热贮存环境中的老化机理,开展了77%相对湿度、60℃和77%相对湿度、20℃条件下的贮存老化试验,实时监测了推进剂最大抗拉强度、冲击感度、邵氏硬度、热老化过程中质量的变化规律。研究发现:2种推进剂在湿热贮存环境下,最大抗拉强度随老化时间的延长持续下降;黏合剂分解是造成2种推进剂硬度变化的主要因素,且HTPB推进剂内部黏合剂受影响更大;NEPE推进剂冲击感度随老化时间增加逐渐降低,而HTPB推进剂则存在感度值回升现象;2种推进剂在湿热环境中质量均增大,且HTPB推进剂吸湿性更强。     

HTPB推进剂贮存老化建模及寿命预估研究综述

HTPB复合固体推进剂是火箭发动机的动力之源,其贮存寿命和性能优劣决定了火箭发动机的寿命和作战性能的发挥,因而研究HTPB复合固体推进剂的贮存老化模型及寿命预估具有重要的军事和经济意义。本文对复合固体推进剂贮存老化性能的研究方法进行了介绍,并综述了国内外贮存寿命老化建模的研究进展,针对推进剂实际贮存可能出现的问题对未来贮存寿命预估的发展趋势进行了预测。研究结果表明,现代仪器的运用可以弥补传统仪器在固体推进剂老化性能研究上的不足,但是还存在研究手段单一、测试方法存在误差、没有形成统一的系统等缺点;推进剂的老化过程比较复杂,结构完整性分析和老化试验相结合的方法可以对推进剂贮存性能和寿命预估进行系统性的研究,得到的结果更准确,可靠性更高。分段老化建模作为推进剂寿命预估研究的新方向,具有很大的发展空间。     

硝酸酯火药安全贮存寿命的预估方法和结果

介绍了热加速老化试验预估火药安全贮存寿命的方法原理。对硝酸酯火药进行不同温度（95,90,85,75和65℃）的热加速老化。以有效安定剂消耗一半所需时间（τ）作为安全贮存寿命的临界点,对不同温度（t）下的τ值,用线性最小二乘法按Bethelot方程进行线性回归,预测了硝酸酯火药在常温（30℃）下的安全贮存寿命。收集了80余种硝酸酯火药安全贮存寿命的预估结果。结果发现,一般单基、双基、三基发射药和双基推进剂的安全贮存寿命在40a以上,而加入AP、TEGN等成分改性的双基发射药和推进剂安全贮存寿命大多低于40a。比较了4个温度点与5个温度点回归处理结果的差异。提出取消90℃试验,必要时增加55℃试验的建议。根据硝酸酯火药老化分解速率的温度系数和低温试验统计结果,提出单温度（65℃）短周期预测硝酸酯火药安全贮存寿命的简便方法。     

预估FH－94固体推进剂使用寿命置信下限的研究

通过提高温度，模拟贮存条件下的老化，获得伸长率变化速率与老化时间和温度的关系，以单向拉伸性能伸长率的下限值作为推进剂的寿命终点判据，在一定置信度下，预估了２０℃和２５℃下ＦＨ－９４固体推进剂的使用寿命置信下限。     

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。     

FH－94固体推进剂的可靠度评估和可靠贮存寿命预测研究

以单向拉伸性能（伸长率）的下限值作为推进剂的失效判据，根据样本标准偏差和均值，评估了题称推进剂的可靠度。通过提高温度，获得伸长率变化速率与老化时间和温度关系，由此预估了２０℃和２５℃下，置信度０．９０，可靠度置信下限分别为０．９９０和０．９９９时的可靠贮存寿命。     

HTPB推进剂贮存老化对其反复拉伸破坏能的影响

由单轴反复拉伸试验分别研究了含键合型防老添加剂和防老剂 H的 HTPB推进剂破坏能与贮存老化时间的关系。结果表明 ,键合型防老添加剂能增强氧化剂与粘结剂基体间的界面粘接能力 ,使其推进剂的破坏能低于含防老剂 H的推进剂     

HTPB推进剂湿热加速老化实验研究

对HTPB推进剂进行了不同湿热条件下的加速老化实验,并测量了不同老化时间推进剂的失重百分数、力学性能以及恢复吸湿后力学性能的恢复情况,描述了湿热老化实验过程中的实验现象,结合温度和湿度对推进剂作用机理,对实验现象、力学性能的变化和恢复情况进行了分析。结果表明：HTPB推进剂在湿热老化过程中发生了组分分解、降解和迁移,同时产生“晶析”现象;湿热老化过程可以分为三个阶段,其中第一阶段为吸湿占主导的阶段,第三阶段为氧化交联占主导的阶段,第二阶段与湿热老化的应力水平有关,温度≥60℃、湿度≥75%RH条件下为高聚物断链稍占优势的阶段,60℃/65%RH条件下为氧化交联稍占优势的阶段;不同湿热老化条件对HTPB推进剂失重的影响机理不同,85%RH湿度条件下以吸湿占主导作用,≤75%RH湿度条件下吸湿、组分的分解和迁移随老化时间分阶段起作用,温度对化学变化起加速作用;物理老化引起的力学性能几乎可以完全恢复,由化学老化引起的性能退化无法恢复。     

基于遗传神经网络的NEPE推进剂寿命预估

将遗传算法和神经网络相结合,建立了NEPE推进剂寿命预估的遗传神经网络(GA-BP)模型.以推进剂拉伸强度下降至原来的50%作为失效判据,利用GA-BP模型预估了NEPE推进剂在常温(20℃,相对湿度65%)下,可靠度为90%时的贮存寿命约为12.5年.结果表明,该模型预估精度高,泛化能力强.     

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。