炭黑补强橡胶的本质

通过橡胶分子状态变化的三个阶段,完成炭黑填充胶的制备过程。第一阶段,在混炼过程中橡胶分子非常牢固地吸附于炭黑粒子的表面,甚至在炭黑填充胶硫化后仍然保持着结合橡胶和结合橡胶的非交联状态;第二阶段,随着炭黑含量的增加,相邻的非交联结合橡胶相互粘合,形成结构连续化的网络;第三阶段,在拉伸条件下,结合橡胶内的橡胶分子被拉伸和取向,最后,变成被拉伸到极限状态的分子链束。在胶料体系中连续形成的分子束,可补偿硫化橡胶网络中的弱点,使橡胶应力增加,拉伸强度提高。     

炭黑粒子的表面形貌及其聚集体的纳米力学属性

介绍炭黑粒子的表面形貌及其聚集体的纳米力学属性,综述聚合物/炭黑复合材料的纳米断裂行为。炭黑原生粒子表面由细小的石墨状晶体无规排列构成,并存在富勒结构碳,呈凹凸不平的原子台阶形貌。快速拉伸时纳米炭黑粒子链发生弹性变形,慢速拉伸时发生塑性变形。单一纳米炭黑粒子链的拉伸强度为(4.5±2.5)MPa,杨氏模量为3.0~8.8 MPa。纳米炭黑粒子链与聚合物之间的界面强度大于粒子链之间及聚合物之间的强度。橡胶/炭黑复合材料受力变形时,纳米炭黑粒子链与结合橡胶分子复合的团聚体在传递应力的同时发生屈服变形,延缓材料破坏。     

新的炭黑补强理论

作者通过应力分析提出了一种具有炭黑补强橡胶新的界面模型的新理论。该新的模型包括：具有不同分子迁移率的双层非交联橡胶层，即在炭黑周围的玻璃态硬质(GH)内层和粘性硬质(SH)外层。由于填充剂含量和应变振幅的增加会导致应力大幅度增加，进而导致在炭黑粒子周围产生应力高度集中，所以这种应力集中会影响到整个填充系统。在大的拉伸、维持大的应力集中情况下，当SH层产生应力硬化的超结构时，只会使拉伸应力大幅度增加。超结构是由定向分子链将炭黑粒子相互连接的网络。大部分的马林斯(Mullins)效应都会导致定向分子链纵向弯曲。这样，在卸载情况下会瞬间大幅度减小应力。在长期停放时，未硫化的SH层的伸直分子链将会相当松弛并恢复到原来的状态。     

橡胶纳米补强中的逾渗机理和界面相互作用的研究

对不同类型炭黑补强SBR拉伸强度的研究表明,炭黑补强SBR中存在着类似于橡胶增韧塑料的逾渗现象,由此提出橡胶补强临界间距的新概念,并讨论其影响因素.对于炭黑补强SBR体系,存在的一个最大临界粒径(原生粒子直径)为80 nm左右.提出了界面相互作用和最小补强粒子尺寸等橡胶补强设计上的新观点.通过计算机模拟,在分子水平上对橡胶和纳米颗粒间的界面相互作用进行了深入研究,结果表明即使在很强的界面作用(氢键范围)情况下,靠近颗粒表面的分子链仍然具有一定的活动性,在界面处能发生吸附脱附的过程.从热力学和动力学的角度阐述了在颗粒的表面不太可能形成橡胶玻璃化壳层.     

炭黑对橡胶补强机理的研究

本文从容积效应、橡胶链的有限伸长、分子链滑动，表面吸附等几方面对炭黑的补强机理加以研究，指出：炭黑对橡胶的补强机理是物理吸附与化学结合共同作用的结果。     

国外橡胶期刊目录精选

乳液聚合丁苯橡胶混炼胶中各种促进剂的化学特性1采用芳香族聚酰胺短纤维减轻卡车轮胎混炼胶的滞后现象26含沉淀白炭黑(纳米填料)的丁苯橡胶的补强和交联39通过实时真应力-真应变双折射体系研究纳米白炭黑粒子对天然橡胶滞后和应变诱发结晶的影响55天然橡胶长期储存中的物理性能之变化72橡胶与黄铜界面上的增粘树脂对铜硫化物粘接层晶体结构的影响之机械学研究82含缠结分子理想网络的橡胶弹性的理论研究-采用该理论评估实际网络中的应力94炭黑中碘值和氮表面积之间的差异120加速聚异戊二烯硫黄硫化的典型混炼胶:I、不含ZnO,含角鲨烯的二苯…     

纳米碳酸钙/炭黑并用对丁苯橡胶性能的影响

研究了纳米碳酸钙／N330炭黑并用比对丁苯橡胶性能的影响。结果表明，随着CaCO3／N330并用比的改变，材料的强度有了显著的提高，特别是CaCOa／N330并用比为20／30(质量份)时复合材料的拉伸强度达到了20MPa以上，同时材料具有较好的弹性和较低的硬度；两种处理剂相比，树脂酸处理的碳酸钙具有较好的性能；表面处理的纳米炭酸钙与炭黑并用，可以降低炭黑填充橡胶的动态滞后，表面处理的纳米碳酸钙的加工性能比纳米炭黑好，可以通过并用纳米碳酸钙来改善炭黑胶料的加工性能。     

纳米材料——“炭黑”对橡胶的补强及展望

通过对纳米材料——“炭黑”补强机理的阐述，剖析了炭黑的纳米级粒径为橡胶提供的是物理结合；炭黑的枝链结构与粒子复杂表面上的活性价键，为橡胶提供的却是化学结合。这种能够形成炭黑一橡胶间的化学与物理的复合结构，是炭黑补强区别于其他任何填料的重要特征。     

采用脉冲核磁共振法研究有关丁腈橡胶的变形行为—炭黑粒子的填充效果

在拉伸状态下,测定旋转——旋转松弛时间(T_2),并对应一定伸长下的应力松弛特性,研究了随着丁腈橡胶(NBR)的变形橡胶网络链的分子运动性与不均匀性的变化。NBR系统的T_2讯号可以分离为两种讯号峰(长讯号峰和短讯号峰)。短T_2讯号峰对应于分子运动受限制的交联点附近的橡胶网络链区域,由此可了解橡胶网络链变形行为的直接特征。短T_2讯号峰的分量,随着变形缓慢增加,反映出为交联点所限制的区域变宽。对于炭黑配合系统皋说,随着炭黑填充量的增加,短T_2讯号峰的增加受到抑制,根据橡胶-炭黑粒子间的相互作用的种种应力松弛机理,可以推断伴之而来的能量损失行为。把炭黑配合体系的橡胶网络链分子运动特性和宏观的变形联系起来,应变增幅作用的假定是一种显然有用的近似方法。     

以天然橡胶为基础的粘结剂和密封剂中炭黑的补强性

在橡胶工业上，炭黑通常用作填料，以达到补强效果，例如改变胶料的定伸应力和拉伸强度。在以橡胶为基础的粘结剂、密封剂和涂料中，炭黑用以提高产品的分子间力或粘结力，并赋予导电性，特别是在涂料中，还可用作载色体(吸光添加剂)，以防止化学降解反应。     

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.     

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.     

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。     

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.     

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.     

基于ATRP法制备的触角状亲水性羟胺树脂的吸硼性能的研究

以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。