氢氧化镁纳米棒的等温分解动力学研究

以六水氯化镁和轻质氧化镁为原料,制备出碱式氯化镁纳米棒;再以碱式氯化镁纳米棒为前驱物,采用沉淀转化法,合成出直径约100—200nm,长约6～10μm的氢氧化镁纳米棒。利用热分析法对氢氧化镁纳米棒进行了等温热分解动力学研究,结果表明,氢氧化镁纳米棒在300℃和350℃时的热分解反应服从随机成核和随后生长机理、积分机理函数g（α）=[-ln（1-α）]^1/m,表观活化能E=153kJ／mol,指前因子A=5．83×10^12s^-1。     

片状氢氧化镁阻燃剂的制备、表面改性及其测试

以六水氯化镁和氢氧化钠为原料,采用两步法即氢氧化钠沉淀-水热处理过程制备出湿氢氧化镁固体,再以硅烷偶联剂KH550对氢氧化镁表面进行改性制得氢氧化镁阻燃剂.适宜的工艺条件为:水热温度160℃,水热时间6 h;表面改性温度80℃,硅烷偶联剂最佳用量为氢氧化镁理论量的5.0％.结果表明:改性氢氧化镁结晶度高、晶粒形貌规整、...     

表面活性剂对氢氧化镁制备的影响

采用了六水氯化镁-氢氧化钠直接沉淀法制备纳米氢氧化镁。主要研究了硬脂酸、硬脂酸钠、钛酸丁酯和葡萄糖等作为表面活性剂,单独使用和复配使用对氢氧化镁沉降速率和过滤速率的影响。实验结果表明：在反应温度为60 ℃,搅拌时间为0.5 h,搅拌速度为200 r/min,在反应溶液中添加表面活性剂后,氢氧化镁沉降速率和过滤速率显著提高;适宜的表面活性剂为阴离子表面活性剂、复配表面活性剂。本实验为改善氢氧化镁的过滤和沉降性能提供了理论基础。        

氧化镁纳米棒的制备与表征

以六水氯化镁和轻质氧化镁为原料,制备出碱式氯化镁纳米棒;再以碱式氯化镁纳米棒为前驱物,采用沉淀转化法制备出前驱物氢氧化镁纳米棒;再通过前驱物热分解法得到直径150～250 nm,长6～10μm的氧化镁单晶纳米棒。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射(SAED)对产物进行表征与分析,研究了煅烧条件对氧化镁纳米棒形貌的影响,得到了氧化镁纳米棒的最佳制备工艺条件为:煅烧温度400℃,煅烧时间1 h,升温速率3℃/min。     

卤水-氨法纳米氢氧化镁的制备研究

在常压下氨法合成纳米氢氧化镁方法的基础上,通过试验,研究了氨水pH值、Mg2+浓度、氨水滴加速度、温度和分散剂用量等因素对纳米氢氧化镁制备的影响。根据XRD和SEM测试结果,提出了制备纳米氢氧化镁的适宜工艺条件:氨水的pH值13.5、氯化镁溶液浓度为0.5mol/L、氨水的加料速度2.0mL/min、反应温度50～60℃、反应时间60min、分散剂用量为MgCl2量的2%和理想溶剂为乙醇和水的混合溶剂,其体积比为1∶2～1∶1。     

氧化镁纳米棒的晶格畸变及反常红外特性

以六水氯化镁和轻质氧化镁为原料,制备出碱式氯化镁纳米棒;再以碱式氯化镁纳米棒为前驱物,氢氧化钠为沉淀转化剂,合成出氢氧化镁纳米棒;采用煅烧前驱物氢氧化镁纳米棒分解得到氧化镁单晶纳米棒。通过X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、区域电子衍射（SAED）和红外吸收光谱（FT-IR）等手段对所得产物的表征分析结果表明,氧化镁纳米棒的微结构中存在晶格畸变,表现为晶格膨胀,其红外吸收峰出现了红移和蓝移同时并存现象;随煅烧温度的升高,氧化镁纳米棒的平均晶粒尺寸增加,晶格常数减小,晶格畸变量减小。     

均匀沉淀法制备纳米氧化镁粉体的试验研究

以六水氯化镁和尿素为原料,以聚乙二醇辛基苯基醚为分散剂,采用均匀沉淀法制备出颗粒直径约为20～30 nm的氧化镁粉体.通过四因素三水平正交试验确定了液相反应条件对纳米氧化镁晶粒直径的影响程度和最佳液相合成条件.结果表明,影响纳米氧化镁晶粒直径的液相反应因素主次顺序依次为:反应物(六水氯化镁)浓度、反应时间、反应物配比(尿素和六水氯化镁的物质的量比)及反应温度.以纳米氧化镁粉体晶粒直径为控制指标的最佳液相反应条件为:反应物浓度1.5 mol/L,反应时间3 h,反应物配比5:1,反应温度99℃.     

纳米氢氧化镁的制备及其原位改性

以六水氯化镁为原料,氢氧化钠为沉淀剂,采用双向沉淀法,在制备过程中引入表面活性剂制备表面有机化的纳米氢氧化镁,同时提高氢氧化镁浆料的沉降性能。以吸油值、接触角衡量氢氧化镁的改性效果,考察了表面活性剂对氢氧化镁改性效果及氢氧化镁浆料沉降性能的影响。利用纳米粒度仪和红外光谱仪对产物的粒径和结构进行表征。结果表明,不同的表面活性剂对氢氧化镁的改性作用存在一定的差别。在制备过程中,油酸的引入对氢氧化镁的改性效果最好,改性后氢氧化镁的接触角和吸油值明显提高,同时改善了氢氧化镁浆料的沉降性能。FTIR分析证明油酸成功地吸附在氢氧化镁表面。     

氢氧化镁粉体的干燥动力学研究

采用以六水氯化镁为原料,氢氧化钠和氨水为混合沉淀剂的直接沉淀法,制备得到平均粒径约为2μm的氢氧化镁粉体。通过不同干燥介质温度和不同湿物料层厚度的干燥动力学实验,获得氢氧化镁粉体的干燥曲线和干燥速率曲线。采用Weibull函数模型,对实验数据进行拟合分析,得到氢氧化镁粉体的干燥动力学参数和干燥动力学方程,探讨干燥动力学参数的影响因素。研究结果表明,可以用Weibull函数模型来描述氢氧化镁粉体的干燥过程,尺度参数与干燥介质温度及物料层厚度有关,随着干燥介质温度的提高,或物料层厚度的降低,干燥速率增大,尺度参数减小,但形状参数变化不大。     

高分散氧化镁粉体的制备及反常红外特性

以六水氯化镁为原料,氢氧化钠和氨水为沉淀剂,采用直接沉淀法合成出前驱物氢氧化镁粉体;再将氢氧化镁煅烧后得到氧化镁粉体产品。通过X射线衍射(XRD)、扫描电镜(SEM)和红外吸收光谱(FT-IR)等对所得产品进行表征分析。结果表明,在煅烧温度为400℃,煅烧时间为3h的条件下,可以得到高分散性的颗粒状氧化镁;在400℃下煅烧8h得到的氧化镁粉体的红外吸收峰出现了红移和蓝移同时并存现象。     

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。