非水解溶胶-凝胶法合成堇青石的反应过程研究

以自制乙醇铝,正硅酸乙酯和醋酸镁为前驱体,采用非水解溶胶-凝胶法合成堇青石,利用XRD、FT-IR和DTATG研究了醋酸镁的加入时机对堇青石合成的影响,前驱体的反应历程和凝胶加热过程中的相转变历程。结果表明:醋酸镁在铝、硅缩聚反应之后引入更利于合成堇青石;非水解溶胶-凝胶法合成堇青石的前驱体反应过程为:首先自制乙醇铝与正硅酸乙酯发生脱醚非水解缩聚反应形成含Al-O-Si键合的中间产物,然后醋酸镁进一步与之发生脱酯的非水解缩聚反应形成Mg-O-Al和Mg-O-Si键合。以醋酸镁为镁源非水解溶胶-凝胶法可在900℃形成μ-堇青石,μ-堇青石于1050℃转变为α-堇青石,并在1200℃制得α-堇青石纯相;由其制得陶瓷烧结体的热膨胀系数为1.329×10~(-6)/℃,具有良好的低膨胀特性。     

利用煤矸石低温合成堇青石陶瓷粉体的研究

以煤矸石为主要原料,辅以组分氧化物调节配方,采用固相反应在低温下合成了堇青石陶瓷粉体,并利用XRD、SEM对试样进行表征.实验结果表明,以50％的煤矸石辅以50％的组分氧化物配料,在1150～1250℃下煅烧3～5h,合成了形貌不规则的颗粒状堇青石陶瓷粉体;其中,在1200℃保温时间4h合成的粉体粒度分布相对均匀,粒径约20 μm.煤矸石中的杂质可以降低堇青石陶瓷粉体的合成温度,同时也产生了少量二次镁铝尖晶石杂相.     

利用无害化铝灰合成耐火原料研究

以无害化铝灰为主要原料,通过与轻烧镁砂混合,在1 650℃下高温反应合成镁铝尖晶石。与滑石和硅石粉混合,在1 380℃下高温反应合成堇青石。借助X射线衍射仪及扫描电子显微镜研究了其物相组成和显微结构,并将合成的尖晶石用于制备刚玉尖晶石浇注料,研究了其抗渣性。研究结果表明,无害化铝灰可以制得纯净的镁铝尖晶石和堇青石。铝灰基镁铝尖晶石致密性高,其体积密度为3.07 kg/L,气孔率为1%,将其应用在刚玉-尖晶石浇注料中,表现出优异的抗渣侵蚀和渗透能力,其原因与铝灰基尖晶石的高活性有关。合成的铝灰基堇青石的体积密度为1.97 kg/L,气孔率为19%,其致密性优于滑石-黏土-氧化铝系堇青石。     

高能球磨作用对合成堇青石基陶瓷的相组成和相变机理的影响

采用XRD分析研究了由分析纯的氧化物粉末制备堇青石基陶瓷时,高能球磨作用及热处理温度对堇青石陶瓷相组成和相变过程的影响,并分析了高能球磨在堇青石陶瓷烧成过程中的作用.结果表明经高能球磨处理的试样在低温烧成(900℃)时,首先出现中间相镁铝尖晶石(MgAl2O4),但1100℃时中间相又消失;与未球磨的试样比较,高能球磨不仅能够降低堇青石的相变温度,而且可大大加快中间相和原料相向α-堇青石转变的速度;同时发现提高烧成温度有利于中间相向堇青石的转变.此外,还研究了粉末的状态(即是否经成型处理)对堇青石陶瓷相组成的影响.结果表明,加压成型使Si4+、Mg2+和Al3+易于扩散,能促进早期的固相烧结和后期的液相烧结,有利于主晶相α-堇青石的合成,但对相组成没有太大影响.     

堇青石对镁铝尖晶石质耐火材料抗热震性能的影响

镁铝尖晶石堇青石复合耐火材料是以各种级配的镁铝尖晶石和1 ～Omm的堇青石为骨料,0.088 mm镁铝尖晶石和二氧化硅微粉为基质,加入硅溶胶结合剂制成的烧结耐火材料.所获得的材料经过1200℃烧结具有优良抗热震性以及满足要求的其他性能,随着堇青石掺量的增加,材料的抗折强度降低,抗热震性增强.     

SiO2/Al2O3摩尔比对堇青石微晶釉结构与性能的影响

以矿物为主要原料采用生料釉法制备堇青石微晶釉,探究了不同SiO2/Al2O3摩尔比对堇青石微晶釉结构和性能的影响。通过高温显微镜、XRD、FT-IR、SEM等对堇青石微晶釉进行了测试表征,并测试其热膨胀系数、釉面硬度和白度。结果表明:随着SiO2/Al2O3摩尔比从7.7降低到3.5,釉的流动性先提高后降低,釉中存在的主晶相由单一顽火辉石转变为顽火辉石和α-堇青石共存再到单一α-堇青石最后转变为α-堇青石和镁铝尖晶石。且釉中α-堇青石含量先增加后减少,热膨胀系数先降低后升高,釉面硬度先增大后减小,白度先减小后增大;当SiO2/Al2O3摩尔比为4.0时,样品的综合性能最佳,α-堇青石含量最高,为19.8%,釉的热膨胀系数为4.37×10-6(600℃),釉面硬度为6.9 GPa,白度为69.1 Wb。     

粉煤灰堇青石玻璃陶瓷的抗热震性能

粉煤灰堇青石玻璃陶瓷采用处理后的武汉阳逻电厂粉煤灰为主要原料合成.X射线粉晶衍射(XRD)分析样品的主晶相为堇青石,次晶相为尖晶石.图像分析显示堇青石含量达到84.12％.电子背散射图像显示尖晶石和玻璃相均匀弥散分布在堇青石基体中,气孔分布较均匀.粉煤灰堇青石玻璃陶瓷的热膨胀系数α1为2.80×10-6B/℃(1000℃).样品经过在1200℃到室温(空气)的范围分段淬火(温度间隔为200℃)后,材料的弹性模量不但没有下降,反而略有上升,表明材料抗热震能力△T≈1 200℃.     

矿化剂对非水解溶胶-凝胶法合成堇青石粉体的影响

在采用非水解溶胶-凝胶法合成堇青石粉体的基础上,研究矿化剂对非水解溶胶-凝胶法合成堇青石粉体的影响。利用DTA-TG、XRD和FT-IR等测试手段研究了矿化剂种类对非水解溶胶-凝胶法合成堇青石粉体的影响,添加矿化剂条件下非水解溶胶-凝胶法合成堇青石粉体的相转变过程,并对矿化剂的作用机制进行了初步探讨。结果表明:添加矿化剂条件下,非水解溶胶-凝胶法制备的堇青石前驱体凝胶热处理中的相转变过程为:无定型堇青石于900℃开始直接转变为α-堇青石相。硼酸由于能增强了凝胶中的Mg-O-Al、Mg-O-Si和Al-O-Si键合,同时硼离子高温下进入α-堇青石的晶格形成有限固溶体及促进体系形成液相,因而能降低α-堇青石相合成温度。     

铝源种类对熔盐法合成镁铝尖晶石的影响

分别以分析纯Al2 O3和AlCl3为铝源,以分析纯MgO为镁源,在NaCl和KCl混合熔盐介质中,分别在1000、1100、1200和1250℃保温3 h合成了镁铝尖晶石粉体,研究了试样的物相组成、微观形貌和化学组成.结果表明:1)温度的升高有利于MgAl2 O4的形成和结晶.2)以Al2 O3为铝源合成的镁铝尖晶石在Al2 O3原料表面成核生长,晶体结构随着温度的升高趋于完善;以AlCl3为铝源合成的镁铝尖晶石颗粒粒径约为3μm且呈正八面体结构.     

烧成温度对溶胶-凝胶法制备堇青石陶瓷性能的影响

为解决工业生产堇青石烧结温度高的问题,首先以结晶氯化镁MgCl_2·6H_2O、结晶氯化铝AlCl_3·6H_2O和正硅酸乙酯(C_2H_5O)_4Si为原料,按照堇青石的化学计量配比,以溶胶-凝胶法并经600℃煅烧制备堇青石先驱体粉体;然后采用半干压成型法将该粉体压制成Φ20 mm×20 mm的圆柱状试样,分别在950、1 000、1 050、1 100、1 150、1 200和1 250℃保温2 h烧成,检测试样的基本物理性能,并利用XRD和SEM分析物相组成和显微结构。结果表明:溶胶-凝胶法制备堇青石陶瓷,可以降低堇青石的合成温度。在1 250℃的烧成温度下,不添加任何烧结助剂,就可以获得纯度较高的α-堇青石相,试样的体积密度为2.25 g·cm~(-3),达到α-堇青石理论密度的90%,基本达到了致密化烧结。     

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。