La掺杂对(In0.5Nb0.5)0.10Ti0.90O2陶瓷微观结构和介电性能的影响

In和Nb共掺杂TiO₂(INTO)陶瓷在100 kHz以下的巨大介电常数源于内部势垒层电容效应。根据这种电容效应,通过增加晶界对介电性能的贡献来降低其低频介电损耗。因此,将La掺杂到INTO陶瓷中,通过细化晶粒并增加晶界数量来降低陶瓷制备过程中的能耗。结果表明,La掺杂减小了INTO陶瓷的晶粒尺寸,增加了陶瓷中晶界的数量,并且陶瓷中析出LaNbTiO₆二次相,在陶瓷晶粒之间形成高阻态的相界,降低陶瓷的低频介电损耗,优化了陶瓷介电常数的频率稳定性。     

CeO2掺杂(Ba,Sr,Ca) TiO3 基高压电容陶瓷的研究

采用固相烧结法合成0.97(Ba0.6Sr0.3Ca0.1)TiO3·0.03(Bi2O3·3TiO2)陶瓷材料,研究了掺杂稀土氧化物CeO2对陶瓷材料介电性能的影响.随CeO2加入量的增加,材料的介电常数先增大后减小再增大后减小,而介电损耗先减小后增大,击穿场强先增大后减小.当CeO2为0.1wt%时,介电常数最大,εr=2384.当CeO2为0.2 wt%时,获得了介电常数为1730,介电损耗为0.0060,耐压为13.125 kV/mm的高压低损耗陶瓷电容器瓷料.利用SEM分析了不同CeO2加入量时样品的断面形貌,结果表明:CeO2可以抑制晶粒生长,细化晶粒,形成固溶体,而过量的CeO2偏析于晶界.     

Yb掺杂对Ba(Zr_(0.1)Ti_(0.9))O_3陶瓷微观形貌及介电性能的影响

采用溶胶-凝胶一步法制备了Yb掺杂锆钛酸钡基陶瓷,陶瓷样品的容温变化率均符合Y5V标准,通过XRD、SEM等分析检测手段对陶瓷样品进行表征。探讨了Yb掺杂量对锆钛酸钡基陶瓷微观形貌、介电常数、容温变化率及介电损耗的影响。研究表明:随着Yb掺杂量的增大,陶瓷的晶粒尺寸有增大趋势,室温介电常数呈现出先增大后减小的变化趋势;当Yb掺杂量为0.06mol%时,陶瓷的晶粒尺寸较小,陶瓷较为致密,其室温介电常数达到最大值18221,介电损耗较小为0.0061。     

Al掺杂对钛酸钡基陶瓷微观形貌及性能的影响

采用溶胶-凝胶一步法制备了Al掺杂钛酸钡基陶瓷。利用XRD、SEM等分析检测手段对陶瓷样品进行表征。探讨了Al掺杂量对钛酸钡基陶瓷相组成、微观形貌、介电常数、介电损耗及介电弛豫的影响。研究表明:Ba Ti O3基陶瓷粉体样品均为单一的钙钛矿结构;随着Al掺杂量的增大,陶瓷的晶粒尺寸逐渐减小,室温介电常数呈现出减小的变化趋势,而居里温度略有增加;当Al掺杂量为0.03mol%时,陶瓷的晶粒大小均匀,其室温介电常数达到最大值3427,介电损耗小于4%。     

Nd掺杂钛酸钡基陶瓷的制备及性能研究

采用溶胶-凝胶一步法制备了Nd掺杂锆钛酸钡基陶瓷,通过XRD、SEM等分析检测手段对样品进行表征。研究了Nd掺杂量的不同对其微观形貌及介电性能的影响。研究表明:随着Nd掺杂量的增大,钛酸钡基陶瓷的晶粒尺寸增大,介电常数呈现出先增大后减小的变化趋势,介电损耗逐渐减小;当Nd掺杂量为摩尔分数0.07%时,陶瓷较为致密,其室温介电常数达到最大值16032,介电损耗较小为0.0046。     

pH值对CCTO粉体及陶瓷结构、介电性能影响的研究

采用溶胶-凝胶法制备CaCu_3Ti_4O_(12)(CCTO)粉体和陶瓷,详细研究溶液pH值对溶胶凝胶化时间及CCTO粉体及陶瓷结构、介电性的影响。结果表明,随着pH值的增大,溶胶凝胶化时间缩短,凝胶透明度降低,且CCTO粉体颗粒增大,并伴有团聚现象,其相应的CCTO陶瓷大晶粒尺寸减小,小晶粒数量增多。同时也发现随着pH值增加,CCTO陶瓷的介电常数减小,介电损耗增加。当pH值为5.5时,CCTO陶瓷的介电常数高达1.4×10~4左右,且介电损耗降至为0.024。     

Zr掺杂对BaTiO3陶瓷微观形貌及性能的影响

采用溶胶-凝胶法制备了锆掺杂的钛酸钡陶瓷,通过XRD、SEM等分析检测手段对所得锆钛酸钡陶瓷样品进行了表征。系统地研究了Zr掺杂对BaTiO_3基陶瓷相组成、微观形貌和介电性能的影响。结果表明,锆钛酸钡陶瓷样品均为单一的立方相钙钛矿结构,晶粒大小均匀,随着Zr掺杂量的增加,陶瓷晶粒尺寸先增大后减小,孔隙逐渐增多,介电常数先增大后减小,介电损耗先减小后增大。     

锌硼硅玻璃掺杂对钛酸钡陶瓷介电性能的影响

用固相法制备了ZnO-B_2O_3-SiO_2(ZBS)玻璃及ZBS玻璃掺杂钛酸钡基介质陶瓷,研究ZBS含量对陶瓷的密度、结构及介电温度特性的影响,研究表明:随着ZBS玻璃的增加,烧结温度逐渐降低,陶瓷晶体的结晶度逐渐减弱,平均晶粒尺寸先增大后减小,所有的样品的介温曲线都出现了双峰结构,室温介电常数先增加后减小,介电损耗逐渐减小。当ZBS含量为1 wt%时,室温介电常数为1127,介电损耗为0.015。烧结温度为1125℃,满足容温变化率(△C/C25℃≤±15%)的工作温度范围为-55～190℃。     

低温烧结玻璃/陶瓷复合材料的微结构及性能

借助钙长石陶瓷和硼酸盐玻璃良好的介电和热膨胀性能,制备了一系列玻璃/陶瓷复合材料,并对这些复合材料进行了X射线衍射分析、扫描电镜观察和性能测试.结果表明:复合材料的介电常数、热膨胀系数和显微硬度随着陶瓷含量的增加而增加,其介电损耗则随陶瓷含量的增加而减小.陶瓷含量(质量分数≥60%)高的复合材料在高于850℃烧结时析出一定量的α-石英和方石英,这增加了材料的热膨胀系数,但对其介电常数影响不大.所制备的复合材料具有高的相对密度(≥96.5%)、低的介电常数(5～6)、低的介电损耗(0.10%～0.42%)、低的热膨胀系数(4.6×10-6～6.5×10-6/℃)和低的烧结温度(≤900℃),有望用作介电材料和基板材料.     

固态反应法制备CaCu3-xMgxTi4O12陶瓷的介电性能研究

利用固态反应法制备了CaCu3-xMgxTi4O12(x=0,0.2,0.4,0.6,0.8,1.0)陶瓷,并分析探讨了MgO添加量对其介电性能的影响.研究结果表明,添加MgO后陶瓷晶粒有变小的现象,且MgO的添加摩尔比为0.6时其介电常数最佳,但介电常数随频率增加下降也较快;MgO添的加摩尔比为0.2和0.4时虽然介电常数增加较少,但随频率变化幅度却较小.在频率＜1 000 Hz时添加MgO会使陶瓷使的介电损耗大幅上升,这表明添加MgO有降低电阻的效果.     

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。