纤维状海泡石改性氟橡胶复合材料的耐磨性能研究

研究纤维状海泡石的结构及其对海泡石/氟橡胶复合材料耐磨性能的影响。结果表明:海泡石纤维束直径集中在100~200nm,长度为1~5μm,聚集体内孔径为3~100nm;随着纤维状海泡石用量的增大,复合材料的100%定伸应力增大,拉伸强度先增大后减小,拉断伸长率下降;当海泡石用量为15份时,复合材料表现出良好的耐磨性能。     

纤维状海泡石改性氟橡胶复合材料的耐磨性能研究

研究纤维状海泡石的结构及其对海泡石/氟橡胶复合材料耐磨性能的影响。结果表明：海泡石纤维束直径集中在100～200 nm,长度为1～5 μm,聚集体内孔径为3～100 nm;随着纤维状海泡石用量的增大,复合材料的100％定伸应力增大,拉伸强度先增大后减小,拉断伸长率下降;当海泡石用量为15份时,复合材料表现出良好的耐磨性能。     

纤维状海泡石/天然胶乳复合胶膜的力学及热稳定性能

采用乳液共混法制备了纤维状海泡石/天然胶乳复合胶膜,研究了海泡石的结构及复合胶乳的胶体性能,考察了纤维状海泡石用量对硫化复合胶膜力学性能、断裂形态及热稳定性的影响。结果表明,随着纤维状海泡石用量的增加,天然胶乳的黏度增大,机械稳定性下降。复合胶膜的拉伸强度和撕裂强度先增大后减小,500%定伸应力增大,扯断伸长率降低;当纤维状海泡石用量为3份时复合胶膜表现出良好的力学性能。与天然胶乳薄膜相比,纤维状海泡石/天然胶乳复合胶膜的热稳定性有所提高。     

聚吡咯包覆纤维状海泡石改性硅橡胶复合材料的制备及性能

以改性纤维状海泡石（oSep）为载体,采用原位聚合法制备聚吡咯（PPy）包覆的纤维状海泡石（PPy@oSep）导电纤维,再以室温硫化硅橡胶（RTV-SR）为基体制备硅橡胶（PPy@oSep/RTV-SR）复合材料。利用傅里叶变换红外光谱和扫描电子显微镜表征PPy@oSep的分子结构和微观形貌,并用万能电子拉伸试验机和绝缘电阻测试仪测试PPy@oSep/RTV-SR复合材料的力学性能和导电性能,同时研究导电填料PPy@oSep对PPy@oSep/RTV-SR复合材料性能的影响。结果表明,海泡石经表面有机改性后与吡咯单体的亲和性增强,有利于吡咯原位聚合,且被直径20～50 nm的类球状PPy均匀包覆;PPy@oSep的体积电阻率与PPy纳米线相近。随着PPy@oSep添加量的增加,PPy@oSep/RTV-SR复合材料的体积电阻率下降,而力学性能提高;当PPy@oSep添加量为15份时,PPy@oSep/RTV-SR复合材料表现出较好的导电性能和力学性能。     

氟橡胶耐热氧老化性能的研究

研究炭黑N330/N990用量比对过氧化物硫化体系氟橡胶物理性能和耐热氧老化性能的影响,并与双酚A硫化体系氟橡胶进行比较。结果表明:随着炭黑N330/N990用量比增大,过氧化物硫化体系氟橡胶的物理性能和耐热氧老化性能提高,压缩永久变形明显减小;当炭黑N330/N990用量比较大时,氟橡胶的物理性能变化不大;与双酚A硫化体系氟橡胶相比,过氧化物硫化体系氟橡胶的硬度和定伸应力较小,拉伸强度和拉断伸长率较大,耐热氧老化性能较好。     

海泡石协效膨胀型阻燃剂在三元乙丙橡胶中的应用

以三元乙丙橡胶(EPDM)为基体材料,制备了海泡石协效膨胀型阻燃复合材料,研究了海泡石的添加量对EPDM复合材料的硫化特性、力学性能和燃烧性能的影响.结果表明,随着海泡石用量的增加,EPDM复合材料的硫化时间缩短,拉伸强度、撕裂强度和拉断伸长率等力学性能显著提升.适量海泡石可降低EPDM复合材料的热释放量和发烟量,并且...     

玄武岩短纤维增强硅橡胶/氟橡胶复合材料的力学性能及热稳定性能

以硅橡胶和氟橡胶为基体,玄武岩短纤维(BF)作增强相,制备了BF/硅橡胶/氟橡胶复合材料。考察了BF的长度、用量、偶联剂种类以及硫化条件对复合材料力学性能的影响。结果表明,BF的用量为7份、长度为12 mm、硅烷偶联剂为KH 590时,复合材料的综合性能最佳。最佳的一段硫化条件为170℃×10 MPa×30 min,最佳的二段硫化条件为200℃×360 min。改性BF的加入提高了硅橡胶与氟橡胶的相容性,使得复合材料的力学性能和热稳定性能得到提高。     

LGFPP/IFR/SP阻燃复合材料的协同阻燃机理

以海泡石(SP)作为协效剂,研究SP与膨胀型阻燃剂(IFR)协同阻燃LGFPP复合材料的性能。通过极限氧指数(LOI)、垂直燃烧(UL-94)、热重分析(TG)等表征LGFPP/IFR/SP复合材料的协同阻燃性能及协效机理。结果表明:随着SP协效剂用量增加,LGFPP/IFR/SP复合材料的LOI呈先增加后降低的趋势,当SP用量为1%时,复合材料的LOI为29.3%,燃烧等级达到V-0级;Ozawa法计算得到复合材料的活化能随着失重率的增大而增大;在LGFPP/IFR/SP阻燃协效体系中,海泡石主要为化学协效阻燃机理。     

聚酯短纤维含量对其增强橡胶复合材料硫化性能的影响

该文研究聚酯短纤维用量及硫化温度的不同对短纤维橡胶基复合材料（SFRC）硫化特性的影响。结果表明,随着聚酯短纤维用量的增大,复舍材料的Mm呈增加趋势,t90逐渐缩短;随着短纤维含量的增加,硫化平坦性变差,热硫化时间和硫化平坦期很短,此后交联键及链段的热裂解反应剧烈,复合材料性能迅速下降,最大转距和最小转距之差呈上升趋势;随着硫化温度的升高,复合材料的硫化速度加快,焦烧时间缩短,硫化平坦性降低;硫化温度宜选在130℃左右;通过电子扫描显微镜观察,复合材料与短纤维的粘着情况在硫化前后有较大不同,随着纤维用量的增加,纤维和基体的粘着性逐渐降低。     

短切碳纤维/氟橡胶复合材料性能研究

利用碳纤维增强氟橡胶,研究了碳纤维含量对氟橡胶力学性能的影响,偶联剂对碳纤维/氟橡胶复合材料性能的影响,确定碳纤维增强氟橡胶的最佳用量及制备复合材料的最佳硫化条件,通过红外光谱(IR)和扫描电镜(SEM)分析探讨碳纤维/氟橡胶橡胶复合材料的形貌和结构。结果表明,短切碳纤维与氟橡胶的最佳质量比为12∶100,偶联剂为3-氨丙基三乙氧基硅烷(KH500),其用量为2.5份。最佳硫化条件为:硫化时间为15min,硫化温度为170℃,硫化压力为10MPa。红外光谱表明,碳纤维与氟橡胶之间生成了C—Si—O化学键,提高了氟橡胶和碳纤维的相容性,扫描电镜(SEM)表明用偶联剂KH550处理过的碳纤维在橡胶中的排列整齐,无明显断面、孔隙,相界面之间结合得很好。     

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。