风电叶片用高模玻纤的开发与应用分析

以风电叶片专用高模量玻璃纤维为研究对象,将其与E玻纤进行了纤维性能差异对比,并利用相应的玻纤单向布制备层合板,对比了层合板的力学性能和单向布的工艺性能,选取3个型号的风电叶片进行了等刚度换算。结果表明,高模玻纤具有更高的抗拉强度、弹性模量、耐化学腐蚀性以及耐疲劳强度;在特征单层厚度和垂直渗透性能相当的情况下,高模玻纤层合板的力学性能均有不同程度的提升;高模玻纤在风电叶片主梁帽中的应用使得风电叶片的质量减轻和成本降低。     

碳玻混编单向复合材料的性能分析

采用碳纤维质量含量分别为7.4%、10.7%、13.8%的三种碳玻层间混编单向织物制备了纤维增强环氧树脂复合材料,分析了该类材料的力学性能与工艺性能。结果表明:碳玻层间混编复合材料的0°拉伸模量和0°压缩模量均随碳纤维含量的提高而升高,掺入碳纤维后碳玻混杂复合材料的0°拉伸强度比纯玻纤复合材料的有所降低,但随碳纤维含量的增加而升高,碳玻层间混编复合材料的0°压缩强度则没有明显的变化规律;掺入碳纤维后,碳玻层间混编复合材料的90°拉伸强度和模量均有所下降;低碳纤维含量的碳玻层间混编单向织物具有良好的Z向渗透性能。该类新材料未来有望在风电叶片结构减重和成本优化上发挥重要作用。     

(±45°/90°/0°)_s准各向同性层合板的拉伸强度

根据经典层合板理论,层合板(±45°/90°/0°)s是准各向同性层合板,其拉伸刚度在板面内各个方向上都相同,而拉伸强度是随偏轴角θ改变而变化,即强度方面不具有各向同性的特点。本文首先研究(±45°/90°/0°)s这种准各向同性层合板拉伸强度在偏轴角θ从0°至45°之间的变化情况,然后通过分别改变单层板强度参数和弹性常数来研究该层合板的拉伸强度的变化情况,并分析其破坏形式。最后与NCF材料的试验结果进行了比较。     

连续玻璃纤维增强层合片材制备及力学性能研究

采用模压工艺制备连续玻璃纤维增强混编纱层合片材及纤维呈0°、30°、45°、90°排布的连续玻纤增强层合片材。研究了热压温度、保压时间及热压压力对层合片材尺寸及力学性能的影响,确定最优的制备工艺;并分析讨论了片材层数及纤维排布角度对连续玻纤增强层合片材的拉伸、弯曲性能的影响;同时根据冲击试验结果分析了垂直与平行受力方向的增强纤维的不同的承载作用。实验研究表明,层合片材的拉伸、弯曲性能先随层数的增加而升高,但到达一定层数后,其力学性能随层数的增加而降低。且层合片材的拉伸性能随排布角度的增加而降低,而其弯曲强度却随之增加而升高。垂直和平行于冲击载荷的纤维皆能吸收冲击能量,其中垂直方向纤维承载能力更强。     

碳纤维增强铝合金层合板拉伸性能研究

采用试验方法与理论分析相结合,对两种不同纤维铺层结构的碳纤维增强铝合金层合板(CARALL)开孔前后的拉伸性能进行了比较研究,得出了开孔前后不同纤维铺层结构的层合板拉伸性能变化规律,并给出了作为拉伸构件的碳纤维铺层结构建议,提出了应用金属体积分数理论和点应力准则预测层合板开孔前后拉伸性能的方法。     

高应力水平下T700/MTM46复合材料层合板拉-拉疲劳性能研究

本文研究了T700/MTM46复合材料层合板在高应力水平下的拉-拉疲劳性能。首先开展了层合板静拉伸试验研究,得到了静拉伸强度、模量和破坏应变,各项静力性能指标分散性小,静力破坏模式以小范围内的脆性断裂为主。然后根据得到的静强度确定疲劳应力水平,开展层合板拉-拉疲劳性能试验研究,各应力水平下疲劳寿命分散性大,且并没有随应力水平高低表现出规律性;疲劳破坏模式以分层失效为主,几乎整个工作段长度内都出现了严重的分层现象;疲劳应力水平越高,破坏时刚度下降程度越小,且归一化刚度退化曲线表现出"快-慢-快"三阶段性;疲劳过程中损伤起源于90°层,且在疲劳过程中该层内的损伤扩展最为严重,0°层的损伤出现最晚,但是0°层纤维断裂预示着即将发生灾难性的疲劳破坏。     

重力效应对VARTM工艺中树脂充模过程的影响

采用真空辅助树脂传递模塑(VARTM)工艺制备了环氧树脂/亚麻纤维复合材料层合板,记录了树脂在不同树脂流动倾角下的充模时间。通过对层合板进行拉伸、弯曲性能测试,研究了树脂流动倾角对复合材料层合板力学性能的影响。结果表明,在VARTM工艺过程中重力效应对树脂充模时间和层合板力学性能有显著影响;充模时间随着树脂流动倾角的增大(从–90°至90°)而增加;复合材料层合板的拉伸强度、拉伸弹性模量、弯曲强度、弯曲弹性模量等均随树脂流动倾角的增大而增大,树脂流动倾角对弯曲强度的影响最大,且对强度的影响高于模量。由于树脂流动倾角影响了树脂与亚麻纤维的结合情况,导致树脂流动倾角为–90°和90°的复合材料层合板在拉伸与弯曲失效时拥有不同的失效形式。     

风电叶片用碳/玻层内混杂VARI成型复合材料结构与性能研究

采用真空辅助树脂灌注成型(VARI)工艺制备碳纤维/玻璃纤维(碳/玻)层内混杂织物的复合材料层合板,系统研究了不同混杂比的层内混杂复合材料的结构与性能。结果表明,随着碳纤维含量的增加,碳/玻层内混杂复合材料的0°拉伸强度逐渐增加而90°拉伸强度稍有下降;0°压缩强度和压缩模量均有上升;弯曲强度稍有降低而弯曲模量逐渐升高;层内剪切强度几乎维持不变;混杂复合材料的储能模量在混杂比达到1∶1时最高,随碳纤维含量继续增加而下降,碳纤维含量的提高也使混杂复合材料的内耗峰明显下降,界面阻尼降低;扫描电子显微镜观察复合材料90°拉伸断裂截面发现,不同混杂比的层内混杂复合材料中环氧树脂对纤维浸润充分,几乎没有观察到纤维拔出与基体的气孔缺陷。     

多向玻碳纤维混杂复合材料的拉伸性能北大核心

为探讨±45°铺层比例对玻碳纤维混杂复合材料拉伸性能的影响,对层间混杂和夹芯混杂分别设计4种铺层方案,并进行拉伸性能实验。通过经典层合板理论对试样的拉伸模量进行估算,与实验结果对比并分析误差。基于混杂效应及±45°铺层比例的影响,对经典层合板理论结果进行修正。结果表明:在±45°铺层比例为40%时,±45°铺层可以对横向应力和剪应力起到很好的平衡作用,从而有效提高复合材料的拉伸性能;混杂效应及±45°铺层比例对经典层合板理论与实验结果的误差都有影响,提出的修正公式可在一定程度上反映其影响,并且可以得到更加准确的拉伸模量估算结果。     

双轴向经编和三维正交机织增强复合材料拉伸性能实验研究

为对比双轴向经编和三维正交机织玻纤复合材料沿0°和90°方向拉伸性能,分别以0°/90°双轴向经编织物和三维正交机织物为增强体,E-2511-1A环氧树脂/2511-1BT固化剂为基体,通过VARTM成型,测试试样沿0°和90°拉伸性能。结果表明,该双轴向经编复合材料仅在0°方向拉伸强度和当量强度略高,弹性模量和当量模量均弱于三维正交机织复合材料,这与增强体纱线线密度和织造密度紧密相关。复合材料拉伸断裂截面显示,三维正交机织物内Z纱有效改善了双轴向经编复合材料易拉伸分层失效和断裂截面处纤维抽拔、脱粘等问题。     

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。