中间相沥青纤维在不同氧气浓度下氧化稳定化过程的研究

研究了萘系中间相沥青在不同氧气浓度下氧化稳定化过程，以期改善炭纤维的力学性能和缩短氧化稳定化时间，与空气相比（氧含量为２１％），在较低的氧气浓度下（Ｏ２：１０％，Ｎ２：９０％，体积含量）氧化后的纤维，经过后续炭化处理，炭纤维的抗拉强度及模量有一定的提高，而最终氧化终温则一样；在较高的氧气浓度下（３０％，５０％）进行氧化稳定化，可使氧化终温比空气时降低２０℃左右，但炭纤维的抗拉强度及模量有所下降。元素分析数据及红外光谱表明在较高氧气浓度下，沥青纤维与氧气的反应速度大大加快，在不同氧气浓度下稳定化、炭化后而得的炭纤维断面结构及微晶参数没有很大差别。     

苯基硅油集束剂对中间相沥青纤维不熔化过程影响

以中间相沥青为原料,通过熔融纺丝、不熔化和炭化处理得到了中间相沥青炭纤维,利用FTIR和TG-DSC手段研究了沥青纤维的不熔化过程。结果表明,沥青纤维在氧化过程中沥青分子与氧反应形成了耐热的氧桥结构,且反应主要发生在200～350℃。利用DSC、SEM、EDS等手段研究了苯基硅油集束剂对中间相沥青纤维不熔化过程的影响。研究结果表明,集束剂很好地改善了纤维间的静电作用,减少了纤维与导辊间的相互摩擦,有效避免纤维表面产生缺陷。同时集束剂还能够很好地改善沥青纤维的集束性和分纤性,使得纤维排列规整性提高。但是在集束剂作用下,纤维丝束密度过大阻碍了纤维束间的气流流动,减缓了反应过程中的热量释放,易导致热点处纤维的融并。当不熔化温度为290℃、集束剂浓度1%时,炭纤维的抗拉强度为1.36GPa。     

沥青球在空气中的不熔化及炭化

以空气为氧化介质，以０．５℃／ｍｉｎ的升温速度，在不同氧化终温及氧化时间下，对沥青球进行不熔化处理。利用元素分析及红外光谱研究了不熔化过程及其对炭化性质的影响；并利用ＴＧ－ＤＴＧ分析了沥青球的炭化过程。     

用煤焦油研制通用级沥青炭纤维

以武钢煤焦油为原料,通过原料净化、可纺沥青的调制、沥青纺丝、沥青纤维不溶化和不熔化纤纤维炭化工艺研制通用级炭纤维。所得通用级沥青炭纤维样品平均直径为１１．６μｍ,平均抗拉强度为９０５ＭＰａ,平均模量为４２．２ＧＰａ,平均断裂伸长为２．１４％。     

用煤焦油制取通用沥青碳纤维的研究

文中探讨了用煤焦油制取沥青炭纤维的可行性，研究了不同滤材对原料的净化效果及温度，空气量，时间，压力，纺丝速度和不熔化终温等因素对沥青炭纤维质量的影响。     

沥青纤维液相氧化工艺研究

根据不同氧化液处理沥青纤维的效果确定液相预处理主体氧化液,然后优化主体氧化液液相预处理工艺,从而使预处理纤维在空气不熔化时可以减少不熔化时间和终温,并通过炭化处理得到强度较好的炭纤维,最终达到节能的目的。     

沥青基炭纤维气-液混合不熔化工艺的研究北大核心

常用的沥青基炭纤维空气不熔化工艺耗费时间比较长,一定程度上增加了制作成本。为了提高沥青基炭纤维不熔化工艺效率,采用硝酸和空气氧化法复合工艺对沥青基纤维进行交联不熔化处理。该工艺吸取了硝酸氧化速度快的优点,又保留了气相氧化法微观结构好的优势。结果表明,在5%硝酸氧化25 min后继续采用空气氧化达到沥青基纤维的不熔化,进一步炭化所得的沥青基炭纤维比单纯空气氧化法得到的炭纤维性能高,同时整个不熔化时间有所减少,提高了不熔化生产效率。     

通用级沥青纤维的不熔化

以新疆乙烯焦油为原料,制备改性沥青,通过熔融纺丝、不熔化、炭化等工艺制备沥青基炭纤维。利用TG、DSC、SEM等手段,对石油沥青纤维在空气中的不熔化处理进行了研究,并研究不熔化条件对炭纤维微观结构及拉伸强度的影响,分析皮芯结构的形成,以及不熔化过程中张力对纤维拉伸强度的影响。     

空气氧化法制备通用级沥青炭纤维用各向同性沥青

以脱除QI的煤焦油软沥青(软化点59℃)为原料,在常压下300～380℃范围内通过空气氧化制备一定软化点范围的通用级沥青炭纤维用各向同性沥青。考察了空气氧化温度、时间、流量对煤焦油沥青性质和结构的影响。结果表明,空气氧化可有效提高煤焦油软化点,并获得各向同性沥青。采用核磁共振谱、红外光谱和元素分析考察了原料和氧化沥青的分子结构。在360℃空气氧化90～130 min条件下,得到的氧化沥青软化点在190～250℃之间,并表现出良好的可纺性,经熔纺得到10～20μm的沥青纤维。     

煤沥青基高性能炭纤维的研制

本文叙述了在实验室中以太钢改质煤沥青为原料研制高性能沥青炭纤维的过程。通过对初始沥青原料进行溶剂重整预处理、热聚合调制中间相沥青、熔融纺丝、不熔化及炭化处理，制得了强度最高为３９６０ＭＰａ、模量为２６０ＧＰａ的炭纤维。探讨了中间相沥青调制条件、纺丝和不熔化处理条件及形态缺陷对炭纤维质量的影响。     

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.     

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.     

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。