两种补强填料对氟醚橡胶性能的影响

设计补强填料（炭黑N990/硫酸钡）用量和并用比不同的9个试验配方,研究炭黑N990/硫酸钡用量和并用比对氟醚橡胶胶料硫化特性、耐低温性能、物理性能、耐热空气老化性能、耐介质性能和压缩永久变形的影响。结果表明：炭黑N990/硫酸钡用量和并用比对氟醚橡胶硫化胶性能影响较大;随着炭黑N990/硫酸钡用量的增大,氟醚橡胶硫化胶的力学性能更好;氟醚橡胶硫化胶的耐低温性能主要由橡胶的分子结构决定,同时含胶率越高,硫化胶的耐低温性能越好;氟醚橡胶硫化胶的耐介质性能与其交联程度有关,当炭黑N990/硫酸钡用量增大时,橡胶与其形成的交联网络更加密集,硫化胶的耐介质性能提高。     

芳纶浆粕补强炭黑/氟醚橡胶复合材料的研究

研究芳纶浆粕对炭黑N990/氟醚橡胶复合材料的物理性能、微观结构和耐低温性能的影响，为高性能氟醚橡胶复合材料的开发提供参考。结果表明：添加1份未经热处理芳纶浆粕和热处理芳纶浆粕的氟醚橡胶复合材料的硫化特性和动态力学性能无明显变化，100%定伸应力、300%定伸应力、拉伸强度和撕裂强度提高；热处理芳纶浆粕在橡胶基体中的分散性和与橡胶基体的界面粘接性较好，对氟醚橡胶复合材料的补强效果更为显著；添加1份未经热处理芳纶浆粕和热处理芳纶浆粕对氟醚橡胶复合材料的耐低温性能影响较小，可在保持氟醚橡胶复合材料良好的耐低温性能的基础上提高其物理性能。     

氯醚橡胶/丁腈橡胶橡胶共混物性能的研究

研究了共聚型氯醚橡胶／丁腈橡胶共混比、促进剂ＮＡ－２２用量、补强剂及软化剂对共混物性能的影响。结果表明：随着氯醚橡胶用量的增加，共混物的耐低温性、耐热氧老化性、耐油性及耐ＣＣｌ＿４和ＣＨＣｌ＿３性能提高，但拉伸强度降低；当促进剂ＮＡ－２２和半补强炭黑的用量分别为１．５和６０份时，氯醚橡胶／丁腈橡胶（６０／４０）共混物的拉伸强度及撕裂强度出现峰值；使用液体丁腈橡胶作软化剂．使共混物的耐低温性、回弹值、撕裂强度、扯断伸长率及耐油性提高，但耐热氧老化性及耐ＣＣｌ＿４和ＣＨＣｌ＿３性能降低。     

炭黑与氧化锌对于全氟醚橡胶性能的影响

通过比较9种不同用量的炭黑N990、氧化锌补强剂,以探讨它们在改善全氟醚橡胶胶料的硫化特性、物理性能方面的作用。结果表明,炭黑对于橡胶的硫化性能没有明显的影响,随着氧化锌的用量增加,对于橡胶的硫化性能有明显的影响,加入质量分数10%的炭黑N990与10%氧化锌时,橡胶90%硫化时间减少到了112 s。添加补强填料对于其物理特性有着良好的提升。添加补强填料会降低橡胶断裂伸长率。加入质量分数20%的炭黑与质量分数10%的氧化锌时,橡胶硬度提升到了81度,断裂伸长率降低为134%。在一定范围内补强填料的用量不影响其永久压缩变形率。     

填充型氟醚橡胶导热性能研究

以氟醚橡胶为基体.通过添加不同无机导热填料制备填充型导热氟醚橡胶,并考察填料热导率、用量及表面改性处理对氟醚橡胶导热性能的影响.结果表明.填料本身热导率大于21 W·(m·K)-1时对氟醚橡胶导热性能的影响已不明显;增大填料用量可显著提高氟醚橡胶导热性能,但会带来加工和使用性能方面的问题;采用硅烷偶联剂对填料进行表面处理能够增强橡胶与填料间的界面结合,提高氟醚橡胶导热性能.     

滑石粉/炭黑协同补强HNBR的研究

采用滑石粉和炭黑N990两种填料协同补强HNBR,研究了滑石粉/炭黑并用体系对HNBR性能的影响。结果表明,炭黑N990填充橡胶的Payne效应更明显;两种填料并用兼顾了炭黑N990对橡胶的补强作用以及滑石粉对橡胶的增韧作用,且压缩永久变形性能较好,力学性能显著提高,具有较好的协同效果。     

氯醚橡胶加工技术(4)

3.2 补强填充剂 补强填充剂对氯醚橡胶的补强效果与其在二烯类橡胶中的情况大致相同。在补强填充剂中,炭黑的补强效果最好,其次是白炭黑和碳酸钙等。 炭黑种类不同,其补强效果也不同(见图3—3、3—4),粒径小的补强效果大。玻璃化温度低的氯醚橡胶用粒径大的炭黑补强时,硫化胶拉伸强度达到最大值时的炭黑用量多,这与二烯类橡胶相同。对于均聚氯醚橡胶,炭黑用量少一些(20～30份)就可使拉伸强度达到最大值;而对于共聚氯醚橡胶,拉伸强度达到最大值时炭黑用量相对要多一些。炭黑粒径和用量对氯醚橡胶拉伸强度表现的这一趋势,相必对于添加增塑剂胶料,均聚氯醚橡胶与共聚氯醚橡胶并用胶料、不同环氧乙烷聚合比胶种当该也是如此,因此应根据     

老化温度和炭黑填充量对SBR和NBR老化性能的影响

因填料具有低成本以及广泛的工业应用，填料填充橡胶的研究引起了人们广泛关注。大多数橡胶若没有炭黑等填充剂补强是没有实用价值的。炭黑能赋予橡胶硬度、强度、耐热性、可塑性及其他重要性能，具有较好的补强性能。     

炭黑补强丁苯橡胶的力学性能研究

丁苯橡胶不能结晶,所以它是非自补强的橡胶,未补强的纯胶强度低,难以制造出具有使用价值的橡胶制品。炭黑是橡胶工业上最重要的补强性填料,炭黑的性质对橡胶的加工性能和成品性能具有决定的影响。因此本实验选用了不同种类的炭黑,考察了炭黑的粒径及结构度对T2000R胶料的基本性能的影响。实验结果表明:随着炭黑粒径的增加,T2000R硫化胶的拉伸强度逐渐降低,撕裂强度降低。但是硫化胶的耐磨耗性能和定伸应力逐渐增大。     

有机偶联剂在橡胶补强中的应用

前言 高聚物的补强是通过向高聚物中加入或复合补强材料来完成的。补强性能的好坏取决于高聚物与补强材料界面之间的亲合性。 橡胶为有机高聚物,而非炭黑填料(如二氧化硅、碳酸钙、陶土等)为无机物质。前者为疏水性物质,后者为亲水性物质,两者的性质不同,因此要使非炭黑填料在橡胶中具有补强性能,直接应用是很困难的。人们采用一种媒介物质来改变橡胶和填料之间的     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。