水热合成掺镧钛酸铋粉体及其光催化性能探讨

以硝酸铋、四氯化钛和硝酸镧为原料,以氢氧化钾为矿化剂,采用水热法合成了不同镧掺杂量的钛酸铋粉体.用X射线衍射(XRD)和透射电镜(TEM)对所得粉体进行了表征,借助紫外-可见分光光度计考察了样品降解甲基橙的光催化性能.实验结果显示:在水热合成温度为220～280 ℃、保温时间为6 h的条件下,可得到各向异性、短轴为30 nm、长轴大于100 nm的掺镧钛酸铋粉体,且该方法所制备的掺镧钛酸铋(Bi 4-xLaxTi3O12)粉体具有一定的光催化效果.     

镧掺杂钛酸铋铁电薄膜的研究进展

综述了镧掺杂钛酸铋的有关理论,详细介绍了目前镧掺杂钛酸铋铁电薄膜的制备方法、优缺点及其进展。讨论了工艺因素对薄膜性能的影响。认为镧掺杂钛酸铋铁电薄膜是一种具有应用前景的光电材料。     

镧掺杂对钛酸铅粉体形貌及粒径的影响

稀土掺杂钛酸铅系陶瓷是一类重要的电子陶瓷材料,其表面形貌及粒径对材料性能有显著影响。采用水热法,以三水合乙酸铅和钛酸四丁酯为主要原料合成了一系列镧掺杂量不同的钛酸铅粉体,利用XRD、SEM、EDS、LPA等手段对粉体的物相、表面形貌及粒径进行了表征。结果表明:水热条件下制得的粉体中只有极少的镧(Ⅲ)取代铅(Ⅱ)进入晶格,大部分则以氢氧化镧的形式存在于晶粒间界处或被吸附在颗粒表面。未进入晶格的镧使晶粒产生择优取向,生长成棒状。粉体的粒径也因镧的引入而发生规律性变化。随着镧掺杂量的增加,粒径先减小后增大,当掺杂量x=0.05时出现临界点。     

钛酸铋纳米粉体的水热合成与分散

以四氯化钛和硝酸铋为原料,氢氧化钾为矿化剂,在220~260℃水热合成6 h,制备出发育良好的纳米级钛酸铋粉体,并对所得粉体进行了不同方式的分散。借助XRD,SEM,TEM及FT-IR等手段对钛酸铋的晶相组成、粒度、形貌等进行了分析。研究结果表明:所得钛酸铋晶粒的形状为矩形片状,宽度在30 nm左右,长度大于100 nm;未经分散的钛酸铋粉体有团聚现象,团聚体的直径可达500 nm左右,将钛酸铋粉体分散于由正硅酸乙酯、丙烯酸、无水乙醇按一定的配比配成的混合液中,然后用高剪切分散乳化机分散处理,可破坏粉体的团聚,具有很好的分散效果。     

钛酸铋纳米粉体的水热合成与分散

以四氯化钛和硝酸铋为原料,氢氧化钾为矿化剂,在220～260℃水热合成6 h,制备出发育良好的纳米级钛酸铋粉体,并对所得粉体进行了不同方式的分散.借助XRD,SEM,TEM及FTr-IR等手段对钛酸铋的晶相组成、粒度、形貌等进行了分析.研究结果表明:所得钛酸铋晶粒的形状为矩形片状,宽度在30 nm左右,长度大于100 nm;未经分散的钛酸铋粉体有团聚现象,团聚体的直径可达500 nm左右,将钛酸铋粉体分散于由正硅酸乙酯、丙烯酸、无水乙醇按一定的配比配成的混合液中,然后用高剪切分散乳化机分散处理,可破坏粉体的团聚,具有很好的分散效果.     

钛酸铋纳米粉体的水热合成及表征

采用分析纯Bi(NO3)3·5H2O和TiO2为原料,以NaOH 为矿化剂,用水热法合成了钛酸铋纳米粉体.讨论了水热反应温度和晶化时间对钛酸铋粉体结构和形貌的影响.研究结果表明,随着水热温度的提高及晶化时间的延长,晶体结晶程度提高;在140～180 ℃和30～72 h的水热条件下,合成了纯的Bi4Ti3O12粉体,其主要由方形片状的纳米晶组成,为典型的钙钛矿结构.并结合实验结果探讨了钛酸铋的水热合成机理.     

镧掺杂钛酸钡粉体的水热改性

以固相法合成的BaTiO3粉体和La(NO3)3溶液为反应前驱物,NaOH为矿化剂,对BaTiO3粉体表面进行镧掺杂水热改性。利用X射线衍射仪、扫描电镜、Fourier红外光谱仪和透射电镜等研究了水热处理后BaTiO3粉体及陶瓷的相组成、晶粒尺寸、颗粒形貌及电性能。结果表明:对不同镧掺杂浓度的BaTiO3粉体进行水热处理后,粉体粒径变小,粒度分布范围变窄,颗粒形貌变得圆整,实现了高温、高压条件下的水热"整形"作用。在BaTiO3粉体颗粒表层形成了一层约50nm厚的富镧层,实现了高温高压下对BaTiO3陶瓷粉体的改性。将改性后的BaTiO3粉体制成陶瓷,其室温电阻率测试结果表明,经水热处理后的粉体改善了镧在钛酸钡陶瓷中的掺杂均匀性,掺杂半导化浓度范围加宽。     

水热法制备钛酸铋粉体的研究

以TiCl4乙醇溶液和Bi（NO3）3·5H2O为原料．NaOH为矿化剂，其摩尔配比的关系为TiCl：Bi（NO3）3·5H2O：NaOH=0．1：0．75：1．5．用水热法合成钙钛矿结构的钛酸铋粉体。讨论了水热合成条件（前驱物和粉体处理、晶化时间、填充率）对钛酸铋粉体结构和形貌的影响。XRD、SEM分析表明，在240℃，晶化时间16h，填充比为60％的条件下，可制备平均晶粒粒径为9～12nm，团聚较轻，颗粒边界明显．球形的钛酸铋粉体。     

共沉淀法制备Bi3.25La0.75Ti3O12纳米粉体

用硝酸铋、硝酸镧和钛酸四丁酯为原料，硝酸、无水乙醇和去离子水为溶剂，氨水为沉淀剂，采用共沉淀法合成了单相铋层状钙钛矿结构Bi3.25La0．75Ti3O12(BLT)纳米粉体。用DTA／TG和XRD研究了BLT前驱体的热行为和晶相转化过程，用场致发射扫描电子显微镜观察了BLT粉体的颗粒形貌和大小的变化。结果表明：共沉淀前驱体溶液的配制过程中，硝酸铋水解生成的硝酸氧铋不利于层状钙钛矿结构BLT相的合成。利用浓度较高的硝酸作溶剂，可以防止硝酸铋的水解，采用氨基共沉淀法直接合成出了单一相的BLT纳米粉体，在煅烧过程中，未出现Bi2Ti2O3焦绿石相。700℃煅烧2h合成的BLT粉体颗粒不大于100nm，颗粒间结合疏松，具有良好的分散性。     

水热法制备纳米铋掺杂氧化锌的影响因素研究

以氯化锌、硝酸铋为主要原料,氢氧化钠为沉淀剂,采用水热法制备了纳米铋掺杂氧化锌粉体。研究了pH值对产物成分的影响,分析了水热时间和水热温度对产物形貌的影响。结果表明pH为9,水热温度为240℃,水热时间为25 h时可以得到微观形貌良好的纳米铋掺杂氧化锌粉体。     

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。