镀银玻璃微珠/硅橡胶导电复合材料导电性能的影响因素

研究镀银玻璃微珠的用量、粒径、表面改性工艺以及导电硅橡胶硫化程度等对镀银玻璃微珠/硅橡胶复合材料导电性能的影响.结果表明,镀银玻璃微珠的粒径越大,复合材料的导电性能越好;湿法预处理和原位改性-分散工艺制得复合材料的导电性能和导电稳定性优于直接干混工艺;导电硅橡胶硫化程度的提高有利于提高材料的导电性能;Payne效应的大小与导电硅橡胶的体积电阻率有很强的相关性.     

镀银玻璃微珠/碳纳米管复合材料制备与性能研究

以镀银玻璃微珠和碳纳米管珠作为导电填料,硅橡胶作为基体,制备出了高导电橡胶。研究了镀银玻璃微珠、石墨烯和镀银玻璃微珠和石墨烯并用对硅橡胶力学性能和导电性能的影响。研究发现:两种填料均能在硅橡胶中分散均匀,镀银玻璃微珠的渗流阈值为250份左右,石墨烯的渗流阈值为20份左右,两种填料并用的渗流阈值为镀银玻璃微珠80份,石墨烯10份,在达到相同导电性时,两种填料并用比添加单一镀银玻璃微珠减少了添加量。     

高导电率金属填充型高导电硅橡胶研究

导电硅橡胶是在硅橡胶中填充导电颗粒通过高温硫化而形成的导电材料。他们具有很好的导电性、良好的密封性和耐高低温性能。可广泛适用于抗电磁干扰密封及压力、环境密封等用途。研制电磁屏蔽高导电硅橡胶,我们采用甲基乙烯基硅橡胶为基胶,研究了不同导电填料(玻璃镀银粉、铝镀银粉、纯银粉)对导电橡胶体电阻率、力学性能的影响。体电阻率达到10-3Ωcm级。试验表明,当硅胶与导电填料体积用量比在1:1.5时候,纯银粉的导电橡胶导电性最好。     

镀银玻璃微珠/硅橡胶导电复合材料逾渗值的研究

研究了镀银玻璃微珠/硅橡胶导电复合材料的力学性能和电性能。结果表明,随着镀银玻璃微珠用量的增加,复合材料的力学性能逐渐劣化,体积电阻率逐步下降。在填料体积分数为38.8%时,复合材料由绝缘体转变为导体,具有明显的逾渗现象。当填料体积分数增大到46%左右时,复合材料体积电阻率呈现一个微弱的拐点。导电复合材料逾渗现象的存在与材料内部导电网络的形成密切相关。     

高导电镀银玻璃微珠/硅橡胶复合材料的结构与性能

探讨了镀银玻璃微珠(SGB)的表面改性、粒径和用量对SGB甲/基乙烯基硅橡胶(VMQ)复合材料的导电性能、力学性能及相态结构的影响,考察了SGB/VMQ复合材料导电网络的影响因素。结果表明,采用硅烷偶联剂改性SGB,可以改善SGB/VMQ复合材料的力学性能和加工性能,其中使用乙烯基三乙酰氧基硅烷(牌号为A-151)还能使其导电性能保持不变。SGB的粒径越大,用量越多,SGB/VMQ复合材料的导电性能越好,当其粒径为41μm、用量300份时,填充的VMQ具有优良的力学性能和导电性能。在满足形成导电通路的前提下,应尽可能地减少SGB的用量,以改善材料的力学性能。     

空心玻璃微珠对硅橡胶动态力学性能的影响

以空心玻璃微珠(HGB)填充甲基乙烯基苯基硅橡胶(MVPQ),研究HGB用量及其粒径对MVPQ硫化胶动态力学性能的影响.试验结果表明,在MvPQ中填充HGB可以增大MVPQ硫化胶的损耗因子(tanδ),当HGB用量为20份时,MvPQ硫化胶的tanδ值最大;HGB粒径越小,MVPQ硫化胶的动态力学性能越好.     

镀银镍粉填充型导电硅橡胶的性能研究

试验研究镀银镍粉填充的甲基乙烯基硅橡胶（MVQ）的物理性能和导电性能。结果表明，随着镀银镍粉用量的增大，MVQ硫化胶的硬度和压缩永久变形增大，拉伸强度和拉断伸长率减小，体积电阻率呈减小趋势；镀银镍粉用量为450份时，MVQ硫化胶的物理性能和导电性能均较优，体积电阻率随热空气老化温度的升高而呈增大趋势，随压缩率的增大而先减小后增大，压缩率以10％～30％为宜。     

碳纳米管在硅橡胶中的应用研究

研究了碳纳米管对硅橡胶力学性能、导电性能和导热性能等的影响。结果表明,随着碳纳米管用量的增大,硅橡胶硫化胶的硬度和定伸应力均逐渐升高,拉伸强度和撕裂强度先升高后降低,拉断伸长率逐渐降低,高温拉伸强度降低;加入碳纳米管后,硫化胶拉伸强度保持率逐步升高;随着碳纳米管用量的增大,硫化胶导电性能明显升高,导热性能逐渐升高。扫描电镜观察结果表明,碳纳米管在硅橡胶基体中分散均匀。     

高导电镀银粒子/硅橡胶复合材料的制备研究

以自制玻璃微珠/银复合粒子作为导电填料、硅橡胶作为基胶,制备出具有高导电性能的硅橡胶复合材料,研究了导电复合粒子的添加量对橡胶复合材料物理性能和导电性能的影响。结果表明:自制玻璃微珠/银复合粒子的体积电阻率为3.14×10-4Ω.cm,导电性能优良;随着复合粒子添加量的增加,硅橡胶复合材料的导电性能和邵尔A硬度增加,但其它力学性能却呈下降趋势。当复合粒子的添加量为300phr时,硅橡胶复合材料的体积电阻率达到0.009Ω.cm,表现出优良的导电性能。     

导电型室温硫化硅橡胶的研究

研究了炭黑的结构和配合量对室温硫化硅橡胶导电性能和力学性能的影响, 以及室温硫化硅橡胶基胶摩尔质量对导电性能的影响。结果表明： ７ 份乙炔炭黑能赋予室温硫化硅橡胶良好的导电性, 当乙炔炭黑用量为１０ 份时, 室温硫化硅橡胶的体积电阻率达到６０ Ω·ｃｍ ; 摩尔质量较低的硅橡胶导电性能更佳; 同时, 乙炔炭黑能提高硅橡胶的拉伸强度和硬度。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.