纳米Bi2O3·SnO2的制备及对RDX热分解特性的影响

为了研究纳米Bi2O3*SnO2对推进剂燃烧的催化作用,以BiCl3和SnCl4*5H2O为原料,采用共沉淀法制备出纳米Bi2O3*SnO2粉体,产物的粒径约为5 nm.用DSC测试了纳米Bi2O3*SnO2对RDX热分解特性的影响.结果表明,纳米Bi2O3*SnO2对RDX热分解有明显的催化效果,使RDX的分解峰温前移了13.7 ℃,放热量增加665 J/g,活化能降低49.42 kJ/mol.     

纳米ZnO/SnO2粉体的制备及其光催化性能的研究

以SnCl4·5H2O、ZnNO3·6H2O、HCl、NaOH为原料,采用共沉淀法制备出纳米ZnO/SnO2纳米复合催化剂粉体,以降解甲基橙溶液反应为模型,考察了不同比例ZnO/SnO2纳米粉体的光催化活性,探讨了煅烧温度对催化剂催化活性的影响.并用差热失重分析仪(TG/DSC)、透射电镜(TEM)、X-射线衍射(XRD)测试手段对其进行了表征.结果表明:ZnO复合SnO2后,光催化活性明显提高,其中以ZnO/SnO2在ZnO∶SnO2=4∶1的情况下复合催化剂光催化性能最优;热处理温度在650℃保温时间2h所得到的复合催化剂催化性能最好.     

溶胶-凝胶-共沸蒸馏技术制备纳米SnO_2粉体

以SnCl4.5H2O为原料,NH3.H2O为沉淀剂,采用溶胶-凝胶-共沸蒸馏技术制备纳米SnO2粉体,实验考察了原料浓度、反应温度、反应终点pH值、干燥脱水方式、焙烧温度等工艺条件对纳米SnO2粉体粒径的影响,得出最佳工艺条件为:SnCl4溶液浓度为0.2mol/L,氨水浓度控制在8%~10%,终点pH值控制2.5,反应温度65℃,温度为500℃时焙烧3h。该制备工艺分别采用醇洗和共沸蒸馏两种脱水方式,将制备得到的粉末用BET、FT-IR、TG-DSC、XRD和TEM等进行表征,采用共沸蒸馏脱水工艺所得的SnO2粉末最小平均粒径可至7.2nm,且无团聚存在。     

两步沉淀法制备纳米Cr_2O_3粉体的研究

为制备分散均匀且超细的纳米Cr2O3粉体,以Cr(NO3)3·9H2O为主原料,以聚乙烯吡咯烷酮(即PVP)为分散剂,采用两步沉淀法制备了纳米Cr2O3粉体。在Cr(NO3)3浓度为0.031 6 mol·L-1的条件下,研究了沉淀剂种类(氨水、碳酸钾和水合肼)、p H(4.8、5.2、6.5、7和7.9)及煅烧温度(300、400、450和500℃)等对合成纳米Cr2O3粉体晶粒尺寸的影响,并采用差热分析、FE-SEM及XRD等对所合成粉体进行了表征。结果表明:随煅烧温度及p H的升高,纳米Cr2O3粉体的晶粒尺寸先减小后增加。在Cr(NO3)3浓度为0.031 6 mol·L-1、以氨水为沉淀剂、p H=7、煅烧温度为450℃及保温时间为2 h的条件下可以制得晶粒尺寸在20 nm左右、分散良好的纳米Cr2O3粉体。     

二氧化锡纳米粉体的制备及表征

本文以廉价的SnCl4·5H2O为母盐,分别以NH3·H2O为沉淀剂,采用溶胶—凝胶法和以CO(NH2)2为沉淀剂,利用微波水热法制备SnO2纳米粉体。利用X-射线衍射(XRD),傅里叶变换红外光谱(FT-IR),透射电镜(TEM)技术对产物进行表征。结果表明：溶胶—凝胶法制备的SnO2粉体颗粒约为80nm但颗粒大小分...     

撞击流反应合成纳米二氧化锡

在浸没循环撞击流反应器中,以SnCl4·5H2O和尿素为原料,通过均匀沉淀法制备出金红石结构的纳米SnO2,用XRD和TEM等技术对SnO2粉体进行了表征,探讨了反应温度、原料配比、反应时间、煅烧时间及螺旋桨转速等因素对收率的影响.结果表明,反应时间对收率影响较大,而反应温度和螺旋桨转速对收率的影响较小;在最优工艺条件下制备的SnO2粉体粒径在20 nm左右,粒径分布窄,分散性良好.     

均相法制备SnO_2-ZrO_2/ZST陶瓷及其Q值的研究

以ZrOCl2·8H2O和SnO2为原料,用均相共沉淀法制备纳米ZrO2包裹SnO2粉体(SnO2-ZrO2),再以SnO2-ZrO2粉体、SnO2、TiO2和ZrO2为原料,用固相法制备(Zr0.8Sn0.2)TiO4(ZST)陶瓷。TEM观察证明:SnO2-ZrO2粉体是纳米ZrO2包覆微米SnO2粉体。用该粉体制备的ZST陶瓷研究表明:SnO2-ZrO2粉体能降低ZST陶瓷烧结温度和改善介电性能。XRD和SEM分析表明,ZST陶瓷的主晶相是单相(Zr0.8Sn0.2)TiO4;用SnO2-ZrO2(Sn4+/Zr4+摩尔比为13.07∶1)取代SnO2的陶瓷显微结构呈现出发育良好的晶粒,分布均匀,气孔少。在烧结温度为1270℃时,得到了Q值为4390(10 GHz),εr为36.8,τf为-3.1×10-6/℃的微波介质陶瓷。     

掺锡氧化铟纳米粉体的制备及表征

以InCl3·5H2O和SnCl4·5H2O为原料,以NH3·H2O作共沉淀剂,采用表面活性剂及有机脱水的方法防团聚,制备了纳米掺锡氧化铟(ITO)粉体,并用X-射线衍射、透射电子显微镜、扫描电子显微镜、比表面测定、傅立叶红外吸收光谱等对制得的粉体进行了表征.结果表明,制得的球形ITO粉体分散性好、粒度均匀,具有单相立方In2O3晶体结构,其平均粒径约40 nm,在714～3333 cm-1范围内对红外光的平均透过率小于5%,是一种优良的红外吸收材料.     

Al2O3/Fe纳米复合粉体的制备及其陶瓷的性能研究

以纳米α-Al2O3和Fe(NO3)3·9H2O为原料,采用非均相沉淀法制备了Fe包裹Al2O3的纳米复合粉体.经XRD、SEM分析发现:复合粉体前驱体经500 ℃焙烧,在H2中700 ℃还原可以得到纳米Fe包裹Al2O3的纳米复合粉体.粉体分散良好,Al2O3表面的纳米Fe粒子呈非连续状态,颗粒为球形,尺寸为30 nm左右,分布均匀.将复合粉体在热压下(30 MPa)烧结获得Al2O3/Fe复合陶瓷,当加入5mol%Fe时,陶瓷的热压烧结温度比单相Al2O3陶瓷降低将近100 ℃.含量为10mol%Fe的陶瓷样品在1500 ℃热压烧结后,断裂韧性可达到5.62 MPa,与相同条件下烧结的单相Al2O3陶瓷(KIc=3.57 MPa)相比提高了近57%.     

纳米复合物PbO·SnO2的制备及对双基和RDX-CMDB推进剂燃烧性能的影响

以Pb(NO3)2、SnCl4·5H2O和NaOH为原料,采用室温固相化学反应法制备纳米复合物PbO·SnO2.用X-射线粉末衍射(XRD)、透射电镜(TEM)、傅里叶变换红外光谱仪(FT-IR)和扫描电镜能谱(SEM-EDS)对纳米复合物PbO·SnO2的组成、大小、形貌进行表征.研究了纳米复合物PbO· SnO2对双基和RDX-CMDB推进剂燃烧性能的影响.结果表明,纳米复合物PbO·SnO2的平均粒径约为40～60 nm,在2～20 MPa压力区,能明显提高双基推进剂的燃速,在10～20MPa的压力指数为0.257.在2～20 MPa压力区,该纳米复合物使RDX-CMDB推进剂的燃速有所提高,与炭黑复合使用时,其催化效率进一步提高.     

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。