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采用酸水解法氯化铜催化制备纳米纤维素晶体(NCC),通过傅里叶变换红外(FTIR)光谱、透射电子显微镜(TEM)观察法和激光粒度分析法对NCC进行性能表征。结果表明NCC聚集态结构为纤维素Ⅰ型;宏观形貌白色丝絮状的NCC,其微观形貌规整,呈棒状;透射电子显微镜观察法分析NCC直径和长度尺寸分布分别为3~27 nm和50~300 nm;粒度分析法NCC平均尺寸为214.3 nm。 相似文献
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利用共沉淀法合成了CaF2纳米颗粒(CaF2NPS),并利用不同量的CaF2NPS制备一系列的聚乙烯醇(PVA)/CaF2纳米复合薄膜。采用X射线衍射法(XRD)、扫描电子显微镜(SEM)对材料进行表征,并利用紫外-可见光谱(UV)和荧光光谱(PL)对材料的光学性质进行了研究。结果表明:CaF2纳米颗粒的形成与立方相有关,晶粒尺寸大约在20~27 nm;CaF2纳米颗粒均匀的分散在PVA膜表面;CaF2纳米颗粒在约300 nm的边缘有强烈的吸收,复合薄膜在200 nm和300 nm左右出现吸收带;CaF2纳米颗粒的PL谱在394 nm和790 nm附近有一系列的发射峰,复合薄膜的PL谱带表明PVA的这3种(间规、无规、等规)分子构象的游离羟基中氧原子的2p2非键电子会发生n←π*电子跃迁。 相似文献
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《中国陶瓷》2019,(1)
通过熔盐(Al_2(SO_4)_3+Na_2SO_4)和Si_3N_4粉体之间的化学反应合成了莫来石晶须,采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)和热重分析(TG-DSC)对合成的莫来石晶须进行了研究。SEM的观测结果表明,莫来石晶须的直径100~300 nm,长度可到达几个微米。HRTEM的研究显示,晶须的晶面间距为0.27 nm,与莫来石相[220]晶面上的晶面间距正好符合。莫来石晶须的生长可用循环氧化-溶解机理进行解释,在此过程中SO_3对SiO_2表面层的刻蚀起着至关重要的作用。 相似文献
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以仲丁醇铝(aluminum tri-sec-butoxide,ATSB)和硼酸为原料,采用阳离子表面活性剂(cetyltrimethyl ammonium bromide,CTAB)辅助溶胶–凝胶法于120℃形成白色干凝胶,再进行焙烧得到硼酸铝纳米棒。采用X射线衍射仪、扫描电子显微镜、透射电子显微镜、X射线能量色散谱仪和Fourier变换红外光谱仪对产物结构和形貌进行表征。结果表明:750℃焙烧产物为具有单晶结构的Al4B2O9纳米棒,,其形貌及直径、长度受ATSB和硼酸摩尔比影响;当ATSB与H3BO3摩尔比为1:2时,Al4B2O9纳米棒直径约为15nm,长度为200~300nm。1200℃焙烧的产物为Al18B4O33纳米棒,其直径为200~500nm,长度约为3μm。对硼酸铝纳米棒的形成机理进行了初步探讨。 相似文献
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水浴加热水解和微波加热水解法合成不同形貌的ZnO亚纳米粒子 总被引:8,自引:0,他引:8
以pH值为11.17的0.005 mol/L的ZnAc2和氨水的混合溶液为前驱体溶液,分别在80℃水浴中加热1 h合成了棒状ZnO亚纳米粒子,和在微波场(频率为2.45 GHz,功率为500 W)中加热2 min合成了花状ZnO亚纳米粒子.用X射线衍射仪和透射电子显微镜研究了产物的结构和形貌.结果表明:产物均为六方晶系ZnO,形貌分别为直径约100~300nm,长度约450~900 nm的棒状,和花瓣直径约为200 nm的花状结构.比较了采用这2种方法所得产物的形貌,并讨论了其形成机理. 相似文献
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采用二步法合成核-壳型二氧化硅/二氧化铈复合微粒 总被引:2,自引:0,他引:2
以正硅酸已酯为硅源,以氨水为催化剂,无水乙醇为溶剂,采用溶胶-凝胶法并经500℃煅烧1 h后制备了SiO2微粒,运用激光粒度分析方法研究了各原料配比对SiO2粒子大小和粒径分布的影响;再以硝酸铈为铈源,碳酸铵为沉淀剂,十二烷基苯磺酸钠为分散剂,加入SiO2微粒,用化学沉淀法,通过控制反应和焙烧条件,经300℃煅烧1 h后成功合成了核-壳型单分散球状SiO2/CeO2复合微粒.并用差示扫描量热仪/热重分析仪、X射线衍射仪、红外光谱仪、扫描电子显微镜、透射电子显微镜和X射线能谱仪等手段以及zeta电位测定对SiO2/CeO2复合微粒的结构、组成和性能进行了表征.结果表明:SiO2/CeO2复合微粒呈规则球状,粒子分布非常均匀,粒径约300~350 nm;CeO2基本上为膜包覆,伴有少量的CeO2沉积,CeO2包覆层厚度约为30nm;SiO2包覆CeO2后所得复合微粒的表面电性质发生变化,其等电点对应的pH值从2.2增大至5.5. 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献