真空辅助树脂注射成型(VARI)研究进展

复合材料低成本制造工艺中,VARI是一种很重要的成型技术,本文对VARI的优点、难点、专用树脂体系、成型方法、树脂分配系统、树脂流动模拟及其国内外应用进行了综述.研究表明,VARI作为一种复合材料的低成本成型技术,已得到广泛应用,尤其是大尺寸、大厚度制件的制造.发展VARI工艺对于降低复合材料的制造成本、扩大复合材料的应用范围有很大作用.由于VARI常用于大尺寸结构件的制造,树脂充模过程的精确模拟对制品质量至关重要,目前国内对此研究仍停留在初级阶段,该方面研究需要引起重视.     

热塑性复合材料在线成型设备研究进展

热压罐成型技术已经成为制备超大尺寸航天飞行器的技术瓶颈,在线成型技术成为非热压罐成型技术的研究重点。然而,在线成型技术制备的热塑性复合材料性能只能达到传统热压罐成型技术的80%。消除与热压罐成型复合材料性能20%差距的关键在于突破在线成型设备中热辅助铺放头的设计制造技术,从工艺装备方面消除或降低影响热塑性复合材料性能的不利因素。本文介绍了在线成型设备的研究和发展过程,比较了两种主流热辅助铺放头即燃气辅助铺放头和激光辅助铺放头的优势和劣势。结合前期的实验结果,提出了激光辅助铺放头的技术指标,并对国内在线成型设备的发展前景进行了展望。     

热压罐外预浸料成型工艺研究进展

为制备与热压罐工艺相同质量与性能的复合材料主承力及次承力结构件,出于降低成本、提高效率、生产更大制件等因素考虑,航空航天领域开发了热压罐外(Out-of-Autoclave, OoA)预浸料成型工艺。与传统的热压罐工艺相比,OoA成型工艺资金投入和运营成本较低,可使用的固化设备、工装、材料范围更广,并能够制造超过现有大型热压罐尺寸的超大型结构件。本文概述了热压罐外预浸料成型工艺的研究进展,介绍了OoA预浸料的形式,对OoA预浸料成型工艺的预压实、纤维密实、缺陷形成和固化周期进行了探讨。最后,讨论了OoA预浸料材料的未来发展。     

适用于OOA成型环氧树脂体系研究

为满足复合材料低成本制造需求，研发出了一款适用于非热压罐(out of autoclave, OOA)成型工艺的环氧树脂LCE201。采用热熔法制作预浸料，将预浸料分别用热压罐和OOA成型工艺制作层压板。比较了两种成型工艺制作层压板的物理和力学性能，结果表明，两者性能相当。使用该预浸料采用OOA成型工艺制作某无人机U型后墙制件，制件厚度及无损结果满足指标要求。     

丙烯酸酯橡胶在复合材料成型中的应用

讨论了丙烯酸酯橡胶做均压板的性能、成型工艺及其在碳纤维复合材料热压罐成型过程中的应用。试验表明，该材料可有效地克服复杂结构制件成型中出现的内外圆角、拐角、尖点处的孔隙现象和制件表面的皱折现象．提高制品的质量。     

格栅形碳纤维复合材料制件成型技术研究

介绍了一种格栅形碳纤维复合材料锥筒制件的成型工艺技术。纤维采用日本东丽公司的M40，基体为648酚醛环氧树脂一三氟化硼单乙胺体系（4211体系），采用铸铝模具、真空袋热压罐成型工艺。通过工艺研究，突破了模具设计与制造、铺层设计、制件外观质量保证、制件尺寸精度控制、成型工艺等关键技术，成型的制件格栅条宽度和厚度均匀，外表光洁，尺寸精度高，满足了设计要求。     

干纤维铺放真空辅助成型复合材料的性能

模拟干纤维铺放原理,将连续热塑性纤维作为定型材料铺放在碳纤维无皱褶织物中间,在热压条件下制备复合材料预成型体,并采用真空辅助工艺制备复合材料试样。测定了采用不同预成型压力、预成型温度以及热塑性纤维含量等预成型条件下制备的复合材料试样的纤维体积含量、力学性能以及微观结构等。结果表明,预成型压力越大,纤维体积含量越高,当预成型压力达到1 MPa以后,纤维体积含量趋于稳定,最高可达65%;在相同预成型压力下,随着定型材料用量的增加,纤维体积含量降低,力学性能随之降低;预成型温度对复合材料的性能影响主要取决于定型材料本身是否发生熔融,若发生熔融,定型材料会对复合材料性能产生不利影响。     

热隔膜工艺温度与成型速率对C形复合材料成型质量的影响

利用自制的热隔膜成型设备制备C形结构碳纤维/环氧预浸料预成型体,通过对预成型体的厚度、缺陷进行表征,考察了工艺温度、成型速率对C形预成型体成型质量和预浸料层间摩擦阻力的影响,分析了预浸料摩擦滑移特性与热隔膜工艺成型质量的关联性。结果表明:通过提高工艺温度、降低抽真空速率可以降低预浸料层间摩擦阻力,得到成型质量较好的C形预成型体。热隔膜成型工艺条件对预浸料层间摩擦滑移特性有重要影响,摩擦阻力可以作为优化热隔膜成型工艺参数的重要依据。     

VARI工艺在大型曲面复合材料制件上的工程化应用研究

对真空辅助树脂传递成型(VARI)成型工艺制造大型曲面复合材料制件的工程化应用进行了研究,对其技术要点进行了重点分析。重点指出了注胶口位置和真空管路设计、辅助材料的合理铺放及封装、树脂的脱泡处理等都是直接影响复合材料制件质量的关键因素。     

复合材料液体模塑成型技术

复合材料液体模塑成型技术(简称LCM)是指将液态聚合物注入铺有纤维预成型体的闭合模腔中，或加热熔化，预先放入模腔内的树脂膜，液态聚合物在流动充模的同时完成树脂／纤维的浸润并经固化成型为制品的一类制备技术。树脂传递模塑、真空辅助树脂传递模塑、树脂浸渍模塑成型工艺、树脂膜渗透成型工艺和结构反应注射模塑成型是最常见的先进LCM工艺技术。这类工艺的共同特点是将纤维预成型体放入模腔内，     

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。