低温烧结PZT-O.5%PbO·WO3压电陶瓷

以固态氧化物为原料,采用一次合成工艺制备锆钛酸铅(lead zirconate titanate,PZT)-0.5%PbO·WO3压电陶瓷,研究摩尔比n(Zr)/n(Ti)、烧结温度对陶瓷性能的影响.结果发现:合成温度900℃保温2 h可以得到钙钛矿结构压电陶瓷.n(Zr)/n(Ti)=1.08时,烧结温度为1 100℃保温2 h,压电陶瓷的综合性能在准同型相界处达最佳:介电常数εT33/ε0=1 593,介电损耗tgδ=0.019,压电系数d33=363.5×10-6C/N,机电耦合系数Kp=0.596,机械品质因数Qm=8 8.4.     

低温烧结PZT–0.5%PbO·WO_3压电陶瓷

以固态氧化物为原料,采用一次合成工艺制备锆钛酸铅(leadzirconatetitanate,PZT)–0.5%PbOWO3压电陶瓷,研究摩尔比n(Zr)/n(Ti)、烧结温度对陶瓷性能的影响。结果发现:合成温度900℃保温2h可以得到钙钛矿结构压电陶瓷。n(Zr)/n(Ti)=1.08时,烧结温度为1100℃保温2h,压电陶瓷的综合性能在准同型相界处达最佳:介电常数ε3T3/ε0=1593,介电损耗tg?=0.019,压电系数d33=363.5×10-6C/N,机电耦合系数Kp=0.596,机械品质因数Qm=88.4。     

溶胶-凝胶法制备(Na0.5Bi0.5)TiO3-BaTiO3基无铅压电陶瓷的研究

采用溶胶-凝胶法制备（Na0.5 Bi 0.5）TiO3-BaTiO3超细粉体。研究结果表明，当热处理温度为800℃时能合成出纯的钙钛矿结构的BNBT超细粉体。另外研究发现，与固相法合成的陶瓷样品相比，sol-gel法制备的陶瓷样品的压电常数和机械品质因子有所提高，但其它的电学性能与固相法合成的陶瓷相近，如介电常数、介电损耗等。     

Na0.5K0.44Li0.06Nb0.94Sb0.06O3无铅压电陶瓷的制备与性能研究

采用传统固相烧结法制备Na0.5 K0.44 Li0.06 Nb0.94 Sb0.06 O3无铅压电陶瓷,研究了烧结温度对陶瓷样品微观结构及电学性能的影响.研究结果表明:烧结温度在1020～1100℃范围内,样品均形成了单一的正交相钙钛矿结构,烧结温度对微观形貌和电学性能有较大影响;与纯KNN陶瓷相比,陶瓷的To-t和Tc均向低温方向移动;当烧结温度为1080℃时晶粒发育比较完全,To-t和Tc分别为45℃和345℃,同时表现出优异的电学性能:d33=200 pC/N,kp=0.365,tanδ=4.67％.     

Na_(0.5)Bi_(0.5)TiO_3陶瓷介电性能的实验研究

采用柠檬酸盐-自燃烧法制备Na0.5Bi0.5TiO3无铅压电陶瓷,系统地研究了制备工艺条件对陶瓷性能和结构的影响。柠檬酸浓度、溶液pH值、烧结温度制度对陶瓷的压电性能有很大的影响。当柠檬酸浓度C=9%,pH=8.5,烧结温度为1130℃时,陶瓷具备最大的压电常数,d33可达71.2pc/n。1130℃烧结陶瓷的XRD表明,陶瓷已形成单一钙钛矿结构的钛酸铋钠主晶相。     

制备工艺对铌锑-锆钛酸铅系压电陶瓷性能的影响

由Nb5+,Sb3+置换锆钛酸铅的B位离子,制备了用作大功率水声换能器材料的铌锑-锆钛酸铅系压电陶瓷.采用固相法合成了0.02Pb(Sb1/2Nb1/2)O3-0.98PbZr1-xTixO3(x=0.44～0.49)粉体.通过X射线衍射及扫描电镜分析.研究了不同锆钛比和烧结温度对陶瓷的相组成、显微结构和介电、压电性能的影响.结果表明:当合成温度为900℃时,获得的粉体的主晶相为钙钛矿结构.当Zr/Ti摩尔比为51/47,烧结温度为1230℃时,各项性能达到最佳值,介电常数ε T 32/ε0为1945,介电损耗tanδ为0.019,压电常数d33为425pC/N,机电耦合系数Kp为0.65,Curie温度θc为352℃.铌锑-锆钛酸铅系压电陶瓷的烧结温度范围宽,具有较强的工艺操作性且θc高.     

BZT-xBCT陶瓷溶胶-凝胶方法合成、烧结及电学性能EI北大核心CSCD

采用溶胶-凝胶方法制备不同组分的(1-x)Ba(Zr_(0.2)Ti_(0.8))O_3-x(Ba_(0.7)Ca_(0.3))TiO_3(BZT-xBCT,0.3≤x≤0.7)纳米粉体并进行常压烧结,研究了BZT-xBCT粉体、陶瓷的结构及其电学性能。结果表明:溶胶-凝胶方法合成的BZT-xBCT粉体具有单一钙钛矿结构,晶粒细小均匀(约为50nm)。与常规固相反应法相比,溶胶-凝胶方法提高了BZT-xBCT粉体的烧结活性,烧结后的陶瓷致密度高(密度>5.46g/cm3),且具有优异的电学性能(BZT-0.5BCT陶瓷的压电系数d33=465pC/N、最大介电常数εmax=8450、剩余极化强度2Pr=23.40μC/cm2)。不同组分的BZT-xBCT陶瓷均表现出介电弛豫现象,随着BCT组分的增加,其Curie温度逐渐升高。     

BZT-xBCT陶瓷溶胶-凝胶方法合成、烧结及电学性能

采用溶胶-凝胶方法制备不同组分的(1-x)Ba(Zr_(0.2)Ti_(0.8))O_3-x(Ba_(0.7)Ca_(0.3))TiO_3(BZT-xBCT,0.3≤x≤0.7)纳米粉体并进行常压烧结,研究了BZT-xBCT粉体、陶瓷的结构及其电学性能。结果表明:溶胶-凝胶方法合成的BZT-xBCT粉体具有单一钙钛矿结构,晶粒细小均匀(约为50nm)。与常规固相反应法相比,溶胶-凝胶方法提高了BZT-xBCT粉体的烧结活性,烧结后的陶瓷致密度高(密度5.46g/cm3),且具有优异的电学性能(BZT-0.5BCT陶瓷的压电系数d33=465pC/N、最大介电常数εmax=8450、剩余极化强度2Pr=23.40μC/cm2)。不同组分的BZT-xBCT陶瓷均表现出介电弛豫现象,随着BCT组分的增加,其Curie温度逐渐升高。     

PVP含量对PZT纳米纤维结构及性能的影响

采用溶胶凝胶-静电纺丝法制备PZT纳米纤维,通过XRD、SEM对不同PVP含量前驱液制备的PZT纳米纤维的物相结构及微观形貌进行表征,将PZT纳米纤维制备成压电陶瓷并测试其压电常数d33。结果表明,通过PVP含量调节PZT纳米纤维的长径比a/c可以有效地调控其烧结活性及压电性能。溶胶凝胶-静电纺丝制备PZT纳米纤维,是实现较低温度下制备较高压电性能PZT压电陶瓷的有效途径。     

BNKT-NKS压电陶瓷的制备及电学性能研究

以碳酸盐和氧化物为原料,无水乙醇为研磨介质,采用固相法合成压电陶瓷体系0.995Bi0.5(Na0.8K0.2)0.5Ti O3-0.005(Na1-xKx)Sb O3(BNKT-NKS),并对其微结构、表面形貌、电学性能进行了分析测试。结果表明,压电陶瓷样品都能形成单一钙钛矿固溶体结构,具有较好的电学性质:x=30%时,d33=149 p C/N,kp=0.315,Qm=139,tanδ=0.037;x=10%时,tanδ=0.037。     

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。