SO42-/SnOz固体超强酸的共沸除氯法制备、表征及其催化α-蒎烯异构化

采用共沸除氯法制备SO42-/SnO2固体超强酸,将其应用于α-蒎烯异构化.该催化剂的最佳制备条件:浸渍液硫酸浓度为1.5 mol/L,焙烧温度550℃,焙烧时间3.0h;反应最佳条件为:反应温度110℃,反应时间3.0h,催化剂用量为松节油中α-蒎烯质量的5％;在该条件下,α-蒎烯转化率为100％,莰烯选择性为64.85％.采用FTIR、XRD、TG-DTA、SEM、BET对催化剂进行了表征.结果表明:相同制备条件下,共沸除氯法制备的SO42-/SnO2较溶胶凝胶法与沉淀法制备的SO42-/SnO2催化活性高,超强酸中心多,颗粒小且均匀,团聚少.     

水热法制备稀土元素掺杂二氧化锡及其对乙醇气敏性能

利用水热法制备了SnO2粉末及掺杂不同稀土离子的SnO2粉末. 通过XRD和气敏测试仪对其结构和性能进行了表征和测试. 结果表明,所制备的SnO2粉末呈四方金红石结构,稀土离子的掺入并没有改变SnO2的晶体结构,也无新晶相的出现. 掺杂镧的SnO2样品(SnO2:La)对乙醇有较高的气敏性. 分析了气敏机理. SnO2:La的灵敏度随着乙醇浓度的增加而增加,随温度的升高呈现波动状,且当温度在250℃时,SnO2:La对1.00′10-4乙醇的灵敏度最大,可达到101.1. 在此条件下其响应时间和恢复时间约为5 s.     

浆料组成对纳米TiO2染料敏化太阳能电池性能的影响

为提高TiO₂光阳极染料吸附量和染料敏化太阳电池(DSSC)的光电转换效率。在制备TiO₂浆料过程中，加入不同量的聚乙烯吡咯烷酮(PVP)、十六烷基三甲基氯化铵(CTAC)、乙酰丙酮、聚乙二醇(PEG 20000)，经机械搅拌得到TiO₂浆料，采用旋涂法在基底上制备多孔TiO₂薄膜阳极，组装成染料敏化太阳电池。采用紫外-可见分光光度计、太阳光模拟器及2400型数字源表测试其紫外可见光吸收光谱以及光电转换效率。利用正交实验探讨了浆料中聚乙烯吡咯烷酮(PVP)、十六烷基三甲基氯化铵(CTAC)、乙酰丙酮和聚乙二醇(PEG20000)对浆料吸光度及DSSC光电性能的影响。研究结果表明，DSSC光电转化效率最佳的配方为：CTAC:0.6 g，乙酰丙酮：1.2 mL,PVP:0.6 g,PEG 20000:1 g，效率(η)达到4.20%。染料吸附量最佳的配方为：CTAC:0.4 g，乙酰丙酮：1.2 mL,PVP:0.6 g,PEG 20000:1.5 g，吸光度为0.386。由此制得的TiO_2<...     

SnO_2空心微球的研究进展

空心微球由于其独特的结构而具有很好的功能性使得它被广泛应用于离子插层,催化剂,光电器件,化学传感器,染料,化妆品和胶囊治疗控释。本文将综述部分SnO2空心微球的制备方法的优缺点及研究现状。     

基板温度对常压化学气相沉积法制备TiO2复合薄膜性能的影响

以Ti(OC3H7)4为先驱体,SnO2:F镀膜玻璃为基板,采用常压化学气相沉积法制备了TiO2/SnO2:F复合薄膜.用扫描电镜、X射线衍射、紫外-可见-近红外透射光谱等手段对样品的物相和性能进行了研究.结果表明:金红石相的SnO2:F底膜促进了TiO2金红石相的形成;当基板温度为480 ℃时,TiO2/SnO2:F复合薄膜出现针状结构,但随着基板温度继续升高,针状结构消失.样品的可见光透过率随基板温度而变化,其值为60%～90%,基本满足建筑物的采光要求.当基板温度为530 ℃时,TiO2/SnO2:F复合薄膜的光催化性能最好.     

Au修饰的全纳米颗粒自组装SnO2/TiO2薄膜及其DSSCs阻挡层应用

采用硼氢化钠还原金盐溶液,制备了晶粒尺寸为5 nm的金溶胶,以静电吸附的方法将Au纳米晶均匀地沉积在FTO玻璃基全纳米颗粒组装的SnO2/TiO2薄膜内,用SEM、EDS、TEM、光电流密度等方法对金修饰的全纳米颗粒组装SnO2/TiO2薄膜(Au-SnO2/TiO2)进行了表征.金纳米晶修饰后,光电流密度较相同厚度的SnO2/TiO2薄膜提高了128.3％,更加有利于光生电子的迁移.将Au-SnO2/TiO2薄膜用作染料敏化太阳能电池(Dye-sensitized solarcells,DSSCs)的阻挡层后,发现复合薄膜有效地阻止了导电玻璃基底上光生电子与电解液中I3-的复合,提高了DSSCs的光电转换效率.不同厚度的Au-SnO2/TiO2阻挡层复合薄膜中,含6层Au-SnO2/TiO2复合薄膜阻挡层的DSSCs最终效率为7.12％,较常用的TiCl4稀溶液预处理FTO玻璃的工艺(6.06％)提高了17.5％.     

H2O对SnO2:F低辐射薄膜结构和性能的影响

以单丁三氯化锡(C4H9SnCl3)为前驱物,三氟乙酸(CF3COOH)为掺杂元素F的引入剂,H2O为催化剂,采用常压化学气相沉积法在浮法玻璃生产线上直接制备了F掺杂的SnO2膜(SnO2:F).采用X射线衍射、扫描电子显微镜、椭圆偏光仪、紫外-可见光谱研究H2O的用量对薄膜的结构和光电性能的影响.结果表明:水对薄膜结构和性能均有显著的影响,随着催化剂H2O含量的增加,SnO2:F为四方相金红石结构,薄膜结晶度提高,致密性得到改善,膜厚有所增加,方块电阻下降.在H2O含量为1.8mol/L时效果较好.     

纳米氧化锡粉体的制备及其表征

以廉价的无机盐SnCl4·5H2O为原料,采用溶胶-凝胶法制备出粒度均匀的超细SnO2粉体,考察了制备工艺对纳米SnO2粉体大小及分散状态的影响,并用BET、XRD、TEM等技术对SnO2纳米粒子进行了表征.实验结果表明:采用NH3·H2O作为沉淀剂,控制反应终点pH为2.5,500℃焙烧3h,可制备颗粒尺寸约10nm的SnO2超细粉体.     

电沉积TiO_2纳米晶薄膜及其光电性能研究

采用阴极电沉积法在导电玻璃基体上制备了TiO2薄膜.运用扫描电子显微镜、X-射线能量散射分析仪和X-射线衍射仪对TiO2薄膜的形貌和结构进行了分析.以N719染料敏化的TiO2薄膜为阳极,0.5 mol/L KI和0.05 mol/L I2的乙氰和乙烯碳酸酯的混合溶液为电解液,碳电极为阴极,组成太阳能电池,通过电流-电压曲线研究了太阳能电池的性能.结果表明:TiO2薄膜的晶型为锐钛矿,其晶粒d平均为28.8 nm.太阳能电池的U开路为0.513 V,J短路为22.8 A/m2,填充因子为0.392,光电转换效率为0.466%.     

新型高性能氧化锡压敏陶瓷的研究

本研究用化学级原料成功地制备出具有良好非线性电流-电压特性的SnO2压敏陶瓷,研究了新型SnO2压敏陶瓷的组成及制备方法,分析了有关性能参数,讨论了组成、显微结构和电性能之间的关系。其目的是开发出性能好、成本低的新一代压敏陶瓷材料。     

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。