水解反应诱导凝固成型制备莫来石陶瓷坯体

根据pH值对硅溶胶分散氧化铝浆料稳定性的影响及机理,用一种免脱气水解反应诱导原位凝固成型技术制备了莫来石陶瓷坯体.在pH值为2.0左右,制备得到A12O3固相体积分数为55%、粘度小于1.0 Pa·s符合莫来石化学计量组成的硅溶胶分散氧化铝浆料,利用尿素的自水解反应,将浆料的pH值从2.0调节到5.0,实现浆料的原位凝固成型,浆料无须脱气处理,可成型得到抗折强度为5.H MPa、显微结构致密均匀的莫来石素坯.     

硅溶胶凝胶工艺成型钛酸铝-莫来石复相陶瓷的研究

利用硅溶胶凝胶化反应实现了钛酸铝-莫来石复相陶瓷的原位凝固成型，研究了钛酸铝在硅溶胶中的分散行为和氯化铵浓度对浆料固化时间的影响规律，从显微结构入手对比分析了不同成型工艺对钛酸铝复相陶瓷强度的影响。结果表明：硅溶胶通过静电排斥和位阻效应显著提高了钛酸铝浆料的分散性。随着氯化铵浓度的提高，浆料的固化时间缩短。硅溶胶凝胶成型试样的烧成强度明显高于干压和凝胶注模成型的试样，其主要原因是由于硅溶胶凝胶成型的试样颗粒分散好、烧结程度高以及在烧成过程中原位形成的细小莫来石对钛酸铝晶粒生长的抑制作用。     

无压烧结SiC凝胶注模成型工艺研究

研究了固相烧结碳化硅的素坯凝胶注模成型工艺。对浆料的分散条件进行了探讨,并对单体的加入量和成型后的素坯的显微结构进行实验。结果表明:用1%氢氧化四甲基铵作为分散剂,分散效果好。单体的加入能降低浆料的粘度,当单体加入量为3%时,素坯密度和脱模时间最佳。成型后的素坯显微结构均匀,结合紧密。     

无压烧结SiC凝胶注模成型工艺研究

研究了固相烧结碳化硅的素坯凝胶注模成型工艺.对浆料的分散条件进行了探讨,并对单体的加入量和成型后的素坯的显微结构进行观察分析.结果表明:用1%氢氧化四甲基铵作为分散剂,分散效果好.单体的加入能降低浆料的粘度,当单体加入量为3%时,素坯密度和脱模时间最佳.成型后的素坯显微结构均匀,结合紧密.     

分散工艺对注凝成型氧化铝陶瓷结构和性能的影响

采用自发凝胶体系注凝成型氧化铝陶瓷,研究了2种分散工艺对浆料的流变性、素坯的气孔率和孔径分布以及陶瓷的体积密度、抗弯强度和显微结构的影响。结果表明:与行星球磨分散的浆料相比,搅拌磨分散的浆料具有较低的黏度,素坯具有较低的气孔率和较小的孔径,烧结后的陶瓷显微结构更加均匀,晶粒尺寸更小,体积密度和抗弯强度更高。由搅拌磨分散的56%(体积分数)固含量浆料制备的坯体经1 600℃烧结后三点抗弯强度达到522 MPa,比相应行星球磨分散所制备的陶瓷高12%。     

分散剂在Al2O3陶瓷原位凝固成型中的应用

陶瓷凝胶注模成型工艺是一种新颖的成型工艺，它将高分子化学单体聚合的思路引入到陶瓷的成型工艺中。通过加入分散剂制备了流动性较好的Al2O3浆料，用改性淀粉原位凝胶注模成型技术制备了具有较高强度和均匀性良好的氧化铝陶瓷坯体。研究了不同分散剂在制备低粘度高固相体积分数Al2O3浓悬浮体中的分散作用，并重点考察了添加不同分散剂的Al2O3浆料的粘度随pH值变化的趋势，对比了不同分散剂对Al2O3浆料的分散效果。     

水基明胶-氧化铝浆料的流变及注凝特性

研究了以氧化铝为原料,以明胶为胶凝剂的注模成型工艺中固含量、分散剂、pH值等对浆料流变特性及素坯性能的影响。结果表明,明胶具有良好的胶凝效果,成功制备出了固相含量高达56vol%,体积密度为2.2g/cm3,抗弯强度达到7.64MPa,内部均匀的陶瓷素坯。     

琼脂糖凝胶注模成型制备氧化铝陶瓷的研究

本文利用琼脂糖做凝胶剂,对凝胶注模成型所需的水性无毒氧化铝陶瓷浆料进行了正交实验,分析了各因素对凝胶注模成型浆料制备的影响,经实验确定了形成较好琼脂糖凝胶注模成型的技术条件,所得陶瓷坯体具有较高的强度和较好的表面质量。     

氧化铝粉体在硅溶胶中分散行为的研究

利用ζ电位、沉降实验、流变学测试研究了氧化铝粉体在硅溶胶中的分散行为。研究发现，硅溶胶分散的氧化铝浆料在pH=10附近沉降量低和粘度最小，表明氧化铝在硅溶胶中分散的最佳pH条件为pH=10左右。还发现氧化铝在硅溶胶中分散受硅溶胶浓度的影响较大，其资料贴度随硅溶胶浓度的增加而减小，在其质量分数为10％－15％之间达到最低；当浓度进一步增加时，其粘度呈现微小的增加。为此，本研究指出，氧化铝在硅溶胶中分散机理为静电位阻稳定，这是由于带负电荷的氧化硅胶粒在氧化铝颗粒表面形成一包覆层，增加了颗粒间的静电斥力位能和产生的一种空间斥力位能。     

石英陶瓷的无机凝胶注模成形工艺研究

本文利用硅溶胶的凝胶化制备石英陶瓷坯体,研究了混合液中硅溶胶与水的比例、石英粉体与混合液质量比、分散剂E80加入量对浆料粘度的影响;研究了催化剂NH4Cl 加入量对浆料初凝时间的影响;测定了所得石英陶瓷坯体的强度.结果表明,当混合液中硅溶胶与水的比例为7∶3,石英粉体和混合液的质量比为4,分散剂E-80的用量为0.4wt％时,浆料的流动性较好;当NH4Cl溶液的用量为8％～10％时,初凝时间在30～60min左右,可以满足成型的要求.采用本工艺得到的坯体显微结构均匀,致密性好,强度较高.     

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。