核壳结构粒子/聚合物复合电介质材料研究进展

综述了基于核壳结构粒子的壳层结构调控导体或陶瓷核壳结构粒子/聚合物复合材料介电性能的最新研究进展,分析并总结了壳层设计、种类、结构、厚度等对复合材料介电性能的影响与调控机理,核壳结构粒子能协同改善复合材料的相对介电常数、击穿强度及降低损耗。界面缓冲区的绝缘外壳改善了复合体系界面相容性与填料分散性,有效抑制了载流子迁移,从而显著降低了体系的介电损耗及漏电流;此外,绝缘外壳还减缓了复合材料内部的电场畸变与集中,提高了材料的击穿强度。指出填料粒子核壳结构的合理设计及其与聚合物基体的协同效应,是提高复合电介质材料击穿强度的发展方向。     

氮化硼填充导热绝缘塑料的研究及应用

六方氮化硼(h-BN)由于其高的导热系数和良好的电绝缘性能在学术界和工业界都受到了广泛的关注。以其作为导热填料制备导热绝缘塑料是近年来研究者的重点研究方向。介绍了氮化硼填充的聚合物基复合材料导热性能的影响因素,包括氮化硼的表面功能化、填料混杂、塑料基体以及填料在基体中的取向。此外,还介绍了氮化硼/聚合物复合材料在电子领域的应用情况。     

六方氮化硼在绝缘导热聚合物复合材料中应用研究进展

本文介绍了六方氮化硼作为高导热、高绝缘性无机填料在聚合物中应用研究进展， 探讨了氮化硼在绝缘导热复合材料应用中的发展方向。     

不同粒径氮化硼填充环氧树脂/玻璃纤维绝缘导热复合材料的研究

以聚砜改性环氧树脂为基体,通过高温模压制备了环氧树脂/玻璃纤维/氮化硼复合材料,研究了不同粒径及不同氮化硼导热粒子用量对复合材料导热性能、力学性能和电性能的影响。结果表明,大粒径粒子有利于复合材料力学性能的提高,小粒径有利于导热性能的提高;随着氮化硼用量的增加,复合材料的导热性能升高,力学性能呈现先增后降趋势,当氮化硼用量为10%(质量分数,下同)时,复合材料的冲击强度和弯曲强度均达到最佳,当氮化硼用量为20%时,复合材料仍保持较好的电性能。     

不同粒径氮化硼填充环氧树脂/玻璃纤维

以聚砜改性环氧树脂为基体,通过高温模压制备了环氧树脂/玻璃纤维/氮化硼复合材料,研究了不同粒径及不同氮化硼导热粒子用量对复合材料导热性能、力学性能和电性能的影响。结果表明,大粒径粒子有利于复合材料力学性能的提高,小粒径有利于导热性能的提高;随着氮化硼用量的增加,复合材料的导热性能升高,力学性能呈现先增后降趋势,当氮化硼用量为10 %（质量分数,下同）时,复合材料的冲击强度和弯曲强度均达到最佳,当氮化硼用量为20 %时,复合材料仍保持较好的电性能。     

聚合物/新型导热填料复合电介质的研究进展

综述了非常规新型导热粒子如纳米金刚石、碳化物、铁电陶瓷及其他无机功能粒子及其填充聚合物电介质的最新研究进展，重点探讨了新型导热粒子的含量、表面改性、加工方式等对聚合物复合材料的导热及介电性能的影响。介绍和分析了基于有机分子晶体为连续声子传递通路改性聚合物导热性能的研究及机理;在基体树脂内利用无机导热粒子及有机分子晶体可构筑连续的声子导热通路，从而达到降低界面热阻、提高体系热导率的目的。相比传统导热粒子，新型导热粒子在提高绝缘聚合物热导率的同时，还赋予体系其他物理性能如磁性、优良介电性能及储能等性能。     

复合绝缘导热胶粘剂研究

以增韧的酚醛环氧树脂为基体树脂,氮化铝、氮化硼、氧化铝混杂粒子为导热填料制备了-新型绝缘导热胶粘剂。研究了填料用量对胶粘剂热导率、热阻、介电常数、体积电阻率等性能的影响,发现填料用量为40％时胶粘剂的热导率为O．99 W／mK,热阻为0．70℃／W,介电常数6,体积电阻率4．6×1012Ω·cm,20℃、200℃、250℃下的剪切强度分别为13．0MPa、10．0MPa、5．65MPa。研究结果表明该胶具备良好的电绝缘及力学性能,可以长期在150℃温度下使用,与不加导热填料的相同胶粘剂相比,具有良好的导热能力。     

氮化硼对硅橡胶复合材料导热性能和力学性能的影响

研究了氮化硼微观结构(团聚体和片状微观结构)和用量对硅橡胶复合材料导热性能、力学性能、基体中分散形态结构的影响。结果表明,随着氮化硼用量的增加,硅橡胶复合材料的拉伸强度和导热系数提高;当硅橡胶复合材料填料用量相同时,氮化硼团聚体比片状氮化硼的导热系数高,但拉伸强度低;当球状结构的氮化硼团聚体用量为100份时,硅橡胶复合材料的导热系数可从0.18 W/m·K提高到1.72 W/m·K;氮化硼团聚体和片状氮化硼填充硅橡胶表现出不同的应力松弛行为,其中高密度氮化硼团聚体表现出了良好的抗压缩性能。     

氮化硼/聚合物复合材料的制备及应用研究进展

氮化硼具有独特的力学性能、化学稳定性、电性能和热稳定性,作为填料在制备聚合物基复合材料方面受到人们的高度重视。本文介绍了原位聚合法及共混法等氮化硼/聚合物复合材料的制备方法,并综述了氮化硼/聚合物复合材料在导热材料、屏蔽材料及其他方面的应用研究进展。     

性能均衡的尼龙6基导热复合材料的结构设计

聚合物基导热复合材料以其独特的优势,如耐环境性和易于加工成型等特点而被广泛的关注和研究。将与尼龙6(PA6)具有部分相容性的尼龙11(PA11)引入尼龙6/氮化硼(PA6/BN)复合材料中,并对其导热性能和力学性能进行了研究。结果发现,在PA6/PA11/BN复合材料中,氮化硼选择性分布在PA6连续相中,PA11相起到体积排除的作用,使得BN在PA6中更有效地形成导热通路,可在较低粒子含量下显著提高复合材料热导率。同时,韧性较高的尼龙11亦起到改善复合材料力学性能的作用。当PA6/PA11体积比为7/3、氮化硼体积分数为20%时,PA6/PA11/BN复合材料热导率达到1.96 W/(m·K),与同等BN含量的PA6/BN复合材料的热导率相比提高了约13.7%,且复合材料的断裂伸长率和拉伸强度也同时得到提高,分别提高了86.72%和13.95%。该研究为制备兼具优异导热性能和力学性能的新型聚合物基导热复合材料提供了一种思路。     

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.     

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.     

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。     

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.     

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.