三维取向短纤维增强复合材料弹性模量的计算

基于单取向纤维增强复合材料的力学性能计算模型,借助于纤维取向分布函数及坐标转换,建立了三维取向短纤维增强复合材料弹性模量的数值计算模型。按该模型对短纤维增强树脂基复合材料的弹性模量进行计算,将其结果与同类材料的实验结果比较验证。结果表明,该模型的预测具有较好的准确性。     

碳纳米管/聚合物基导热复合材料研究进展

碳纳米管（CNTs）由于优异的轴向导热性能,是目前制备高热导率聚合物基复合材料的一类重要填料。本文综述了近年来CNTs增强聚合物复合材料的研究进展,探讨了CNTs/聚合物复合材料的导热机理以及CNTs用量、尺寸及结构、表面改性、混杂CNTs粒子和聚合物基体结构等因素对CNTs/聚合物复合材料热导率的影响。同CNTs/聚合物的电导率相比,热导率远低于预期值,归因于CNTs/树脂界面间的声子频率失配现象导致了声子在界面的散射及很高的界面接触热阻,从而降低了体系热导率。分析和总结了改善体系热导率的方法和措施,采用特殊工艺使CNTs在基体内形成特殊的隔离结构或者取向结构是CNTs/聚合物导热复合材料的未来研究及发展方向。     

纤维增强树脂基复合材料在直升机的应用现状

本文介绍了纤维增强树脂基复合材料相关特征和直升机常用纤维增强树脂基复合材料的种类特性.描述了直升机结构特点以及纤维增强树脂基复合材料在直升机上的具体应用部位和应用现状,并对实际应用部位的结构特点、选材情况和其在直升机上的作用用途等进行了论述,同时对直升机用复合材料未来的发展趋势进行了展望.研究表明,纤维增强树脂基复合材...     

纤维增强树脂复合材料3D打印流场分析与仿真

以纤维增强树脂基复合材料为研究对象,该材料由碳纤维和聚乳酸高分子材料复合而成。利用ANSYS CFX软件模块,对复合材料的流体状态和压力场进行了数值仿真,探究了以熔融沉积(FDM) 3D打印工艺制备纤维增强复合材料的流动特性和打印机理。首先,结合纤维增强复合材料的流动和受力规律,建立了打印流道及复合材料的三维模型;其次,描述了用于数值仿真复合材料的参数,得到了纤维增强树脂复合材料熔融成型时内部流场状态和界面压力分布,并进行了分析讨论;最后,通过实验验证了3D打印用于纤维增强树脂复合材料成型制造的可行性。研究结果为纤维增强树脂基复合材料的3D打印应用提供了必要的仿真与实验基础。     

基于3D打印的三维短纤维增强复合材料强度预测分析

针对目前短纤维增强树脂基复合材料强度仍以实验和二维平面预测为主,提出一种能真实反映纤维空间结构的三维短纤维增强复合材料强度预测模型.基于概率方法修正"混合律模型"对临界区域内纤维的作用进行详细的理论公式推导,建立基于纤维取向、长度和体积分数等因素的三维短纤维增强复合材料强度预测模型.以短碳纤维增强尼龙复合材料为例进行强...     

纤维增强树脂基夹芯复合材料隔声性能的研究

本文对轨道交通车辆安装复合材料头罩的驾驶室进行隔声研究,先从双层纤维增强树脂基夹芯复合材料对称结构和非对称结构的隔声性能进行研究,再对三层纤维增强树脂基夹芯复合材料结构的隔声性能进行探究,接着进一步探究阻尼材料、隔声材料对纤维增强树脂基夹芯复合材料隔声性能的影响,最后根据驾驶室的实际情况,探究空气层和内饰件产品对驾驶室隔声性能的影响。结果表明,对于双层纤维增强树脂基夹芯复合材料结构,在声源侧分配厚的纤维层,比平均分配两侧纤维层可获得更高的隔声性能;对于三层纤维增强树脂基夹芯复合材料结构,将厚度最大的纤维层置于近声源端,将厚度次之的纤维层置于远声端,将厚度最小的纤维层置于中间的结构,其隔声量明显优于双层纤维增强树脂基夹芯复合材料结构;在复合材料背面增加阻尼材料或隔声材料都可提高其隔声性能;考虑内饰件及空气层时,驾驶室的隔声量可提高。     

PBO纤维与石英纤维混编增强氰酸酯树脂基复合材料的研究

结合PBO纤维增强树脂基复合材料优异的介电性能和石英纤维增强树脂基复合材料优异的力学性能,本文设计了石英纤维与PBO纤维体积比55∶45混合编织,同时采用空气气氛对混编纤维表面进行等离子体处理,等离子体处理工艺为400W/10min,制备的氰酸酯树脂复合材料力学性能较纯PBO纤维增强氰酸酯树脂复合材料具有更加优异的性能,弯曲强度提高了62%,层间剪切强度提升了231%,大大加快了PBO纤维复合材料在透波复合材料领域的应用步伐。     

纤维增强树脂基复合材料表面金属化研究进展

对纤维增强树脂基复合材料表面金属化研究进行综述,分别介绍了纤维与树脂在复合前的表面金属化方法,纤维与树脂复合后固化前的表面金属化方法以及纤维与树脂固化后表面金属化方法;并且对复合材料在不同阶段的金属化方法优缺点进行分析介绍,结合航空航天领域在复合材料表面金属化的需求,分析了不同的金属化方法在航天复合材料结构件上的适用性。     

亚麻/聚酯复合材料

以纤维束混合的方式制备脂肪族聚酯和天然亚麻纤维复合材料。研究了加工条件对纤维长度分布的影响以及复合材料的力学性能对纤维含量的依赖性。依据纤维取向度效率系数(η0)的广义混合规律方程,复合材料的拉伸模量随纤维含量变化而变化。随纤维的加入,聚酯/亚麻复合材料的强力趋于减小,这表明基体树脂与增强纤维之间无黏合。为改善基体树脂与纤维之间的黏合作用,对经表面化学改性的亚麻纤维进行了测试。结果表明:当复合材料中体积分数25%的天然纤维被含有醋酸基的纤维所替代时,其强力将增加30%;含有戊酸盐基或表面接枝聚乙二醇链纤维的复合材料强力并无明显变化。     

炭纤维增强复合材料振动性能研究进展

炭纤维增强复合材料的固有频率和阻尼特性受复合材料的组织结构和使用环境的影响。针对炭纤维增强树脂基和炭基复合材料的固有频率和阻尼特性的研究进展进行了系统论述,详细介绍了纤维、基体、纤维/基体的界面及温度对炭纤维增强树脂基和炭基复合材料固有频率和阻尼特性的影响。     

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。