利用高能球磨前驱体低温制备钛酸铝陶瓷粉体

研究目的是探讨机械激活法在低温制备钛酸铝粉体中的应用可能性。采用行星球磨方式对刚玉和锐钛矿型二氧化钛混合粉体进行机械激活处理,并在1100—1300℃温度范围内进行短时热处理制备了纯度高、颗粒细小均匀的钛酸铝陶瓷粉体。研究结果表明,采用高能球磨机械激活处理,可提高粉体反应活性,降低周相反应法制备钛酸铝陶瓷的合成温度。球磨60小时的混合粉体在1300℃烧结钛酸铝的转变率可达98％。     

机械激活对固态反应合成Al2TiO5的作用分析

采用行星式球磨机机械激活处理α-Al2O3和锐钛矿型TiO2混合粉体.在相对低下的条件下合成了高纯度Al2TiO5块体材料,分析了机械激活作用所导致的混合粉体变化过程、产物及对合成Al2TiO5的影响作用.研究表明,机械激活作用是具有时间依赖性的累积过程,而激活过程中所发生的诸如相变、细化、畸变以及磨介杂质的引入对于反应合成Al2TiO5具有有益的作用.     

非水解溶胶-凝胶法制备镁稳定化钛酸铝

采用非水解溶胶-凝胶法合成镁稳定化钛酸铝粉体,研究了镁源种类对钛酸铝低温合成效果和稳定化效果的影响。结果表明:镁粉或氟化镁均不能稳定钛酸铝,而且促进了非水解同质缩聚,导致钛酸铝无法750℃低温合成。无水醋酸镁和乙醇镁在前驱体混合物中与醇铝和醇钛发生反应,形成Mg-O-Al、Mg-O-Ti、Al-O-Ti异质缩聚键合,促进镁离子在750℃时掺入到钛酸铝晶格中,提高其热稳定性。     

氧化镁与氧化铜复合添加对钛酸铝陶瓷微观结构的影响

以三氧化二铝和锐钛矿型二氧化钛为基本原料,氧化镁和氧化铜为添加剂,用行星式球磨机在30:1的球料比下高能球磨30小时。采用干压成型,并在1250～1400℃下无压烧结。烧结体的X衍射谱图显示样品的主晶相为钛酸铝,扫描电镜照片中观察到小颗粒紧密堆积在大颗粒所形成的空隙中。随着成型压力的变化和烧结制度的改变,棒状晶粒形貌有明显的变化。研究表明氧化镁和氧化铜有利于钛酸铝陶瓷低温烧结。在适当的温度制度下,可以得到明显双峰分布的结构。     

原材料与钛酸铝陶瓷性能之间关系的研究

用不同纯度的二氧化钛粉体和不同晶型的氧化铝粉体为原料进行钛酸铝合成研究。结果表明:引入稳定剂和烧结助剂,在一定的烧结温度条件下,这些原材料均可生成具有良好力学性能的钛酸铝陶瓷;在相同的烧成条件下,钛黄粉反应生成的钛酸铝陶瓷比钛白粉反应生成的陶瓷具有更好的力学性能;采用钛黄粉与工业氧化铝粉合成的钛酸铝陶瓷,由于生产成本低,在耐火材料领域具有广泛的应用潜力。     

复合添加剂对钛酸铝材料合成及稳定性的影响

本实验采用正交试验设计,研究了复合添加剂SiO2、MgO以及合成温度三因素对钛酸铝合成与稳定的影响,探讨了复合添加剂对钛酸铝的稳定机理,并在合成的基础上,对钛酸铝进行了烧结后性能测试,结果表明,复合添加剂能较好地使钛酸铝材料保持稳定,MgO与温度对钛酸铝的合成及稳定具有强烈的交互作用,烧结后钛酸铝材料在保持低热膨胀系数前提下抗折强度达52.13MPa。     

氧供体醇对非水解溶胶-凝胶法低温合成钛酸铝的影响

以TiCl4和无水AlCl3为原料,以无水低碳醇为氧供体通过非水解溶胶-凝胶法低温合成了钛酸铝,研究了无水低碳醇种类及用量对钛酸铝合成反应的影响.结果表明:当氧供体按反应式化学计量比用量加入时,在750℃能合成出钛酸铝,其中以乙醇的合成效果最好,异丙醇次之,正丁醇的效果较差;采用甲醇和叔丁醇作氧供体,由于它们的化学活性过大而引发水解反应,不能低温(750 ℃)合成钛酸铝.当醇用量超过化学计量比时,则合成效果显著下降;当醇用量低于化学计量比时,改变乙醇的用量对合成效果影响不明显,而减少异丙醇和正丁醇用量可显著提高钛酸铝的合成效果.     

晶种对溶胶-凝胶法合成钛酸铝粉体的影响

在溶胶-凝胶法合成钛酸铝的工艺过程中，钛酸铝超细粉料被用作晶种直接加入溶胶中，不同条件下煅烧的钛酸铝粉体的X射线衍射图谱表明：籽晶能使钛酸铝的合成温度明显降低、合成率有效提高。     

钛酸铝陶瓷及其研究新进展

为了总结近年来国内外对钛酸铝陶瓷的最新研究进展,推动钛酸铝的研究,本文综述了钛酸铝陶瓷的易分解和低强度机理,着重介绍了采用添加剂法、复合相法以及新的合成、成形、烧结等工艺改善钛酸铝陶瓷性能方面的研究进展,并对其最新的应用研究进展作出简单的介绍,更在此基础上提出了钛酸铝陶瓷的发展动向。     

添加剂和烧成温度对钛酸铝的合成与烧结性能的影响

研究了添加剂MgO和SiO2 以及烧成温度对钛酸铝的合成及烧结性能的影响。结果表明 ,烧成温度的升高促进了钛酸铝的合成与烧结 ;MgO的引入极大地促进了钛酸铝的合成 ,而对于SiO2 来说 ,这种促进作用在高温下才明显 ;MgO和SiO2 在钛酸铝中均有一定的固溶度 ,超过此固溶极限将有新相 (尖晶石或莫来石 )产生 ,从而导致烧结性能随MgO和SiO2 添加量的变化呈现复杂的变化规律     

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。