Scanning Electron Microscopic Studies on the Failure of Rubber-to-Metal Bonded Composites

Scanning electron microscopic studies were conducted to evaluate the failure mechanism of rubber-to-metal bonded composites in the 90° peel test (ASTM D 429-B). It was found that when cohesive failure in rubber takes place, the composites, failing by stick-slip mode, show high peel strength. Moreover, in such cases, there exists a linear correlation between the peel strength and the crosslink density of the rubber vulcanizate.     

金在碱性硫脲溶液中溶解的电化学动力学

研究了金在碱性硫脲溶液中阳极溶解的电化学行为及动力学. 结果表明,硫脲浓度由0增加至0.2 mol/L时,开路电势由-130 mV移至-280 mV,达到稳态的时间由400 s延长至800 s. 循环伏安曲线上正向扫描时700 mV的电流峰为金的阳极氧化峰,850 mV之后阳极电流急速上升为氧气的大量析出,反扫时220 mV处为溶液中金离子的还原峰. 溶液中加入硫脲使金的阳极氧化峰电势负移了30 mV,峰电流则提高了15.5倍. 由于硫脲的分解及其产物对金电极表面的钝化,硫脲浓度由0.05 mol/L增加至0.20 mol/L时,阳极峰电势由655 mV负移至480 mV,峰电流则由1.985 mA降至0.09528 mA. pH值升高有利于金在碱性硫脲溶液中的阳极溶解. 温度由25℃升高至35℃时,峰电流由0.761 mA迅速增加至4.387 mA,峰电势由655 mV负移至596 mV,有利于金的溶解;但温度太高会增加硫脲自身的氧化分解. 金的阳极溶解为不可逆电荷转移反应.     

Characterization and Electroanalytical Application of ω-Mercaptoalkanesulfonic Acid Monolayers on Gold

Self-assembled monolayers (SAMs) of ω-mercaptoalkanesulfonic acid on gold surfaces have been studied by electrochemistry and other surface techniques. In spite of the fact that these monolayers are disorganized, i.e., of “brush” type, they are impermeable to inorganic anions due to their high negative charge. Moreover, we find that an ω-mercaptodecanesulfonic acid (MDS) monolayer is also impermeable to organic species, regardless of their charge, because of its high hydrophilicity. The combination of these properties made it possible to apply gold electrodes modified with MDS for the determination of iron(III) ions in the presence of organic species that are either electroactive throughout the same potential window or form strong complexes with iron(III).     

Electrochemical Formation of CdSe Monolayers on the Low Index Planes of Au

The electrochemical analog of atomic layer epitaxy (ALE) is being studied. ALE is a method for growing thin films of materials using a cycle of surface limited reactions. The surface limited reactions control the deposition by limiting the growth to an atomic layer at a time. In electrochemistry, a surface limited deposition is generally referred to as underpotential deposition (UPD), and UPD is used to form the atomic layers in electrochemical ALE (ECALE). The work presented here is an atomic level study of the deposition of the first few monolayers of CdSe via ECALE: by the alternated UPD of atomic layers of Se and Cd on the low index planes of Au. UPD of Se resulted in the formation of ordered structures on each of the low index planes of Au, as observed by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The subsequent UPD of Cd resulted in CdSe deposits which exhibited 1:1 stoichiometry, as determined by coulometry and Auger electron spectroscopy (AES). The following LEED patterns were observed for the CdSe monolayers: Au(111)(√7×√7)R19.1°, Au(111)(3×3), Au(110)(2×3), and the Au(100)(√2×2√2)R45°. Similar LEED patterns were observed on each surface for deposits formed using up to three ECALE cycles. In situ STM studies of Cd deposition on Se-covered Au(111) indicated the formation of a (3×3) structure, consistent with LEED results, and with previous TEM studies. The same LEED patterns were also observed for CdSe monolayers where Cd was deposited as the first atomic layer. AES indicated that the element deposited first remained on the bottom, and that deposited second remained on top.     

间硝基酚在复合功能树脂上的吸附热力学及动力学研究

选用NDA-88、NDA-99、NDA-150、XAD-4几种吸附树脂对间硝基酚的静态吸附行为进行了研究,结果表明:间硝基酚在NDA-88、NDA-99复合功能树脂上的吸附效果较好。研究了NDA-88树脂对水溶液中间硝基酚的静态吸附等温线,并计算了吸附热力学函数,吸附行为符合Freundlich吸附等温方程,吸附量随温度升高而降低,表明为物理吸附。动力学研究结果表明:吸附速率随温度升高而增大。     

表面吸附的微观机理研究进展

介绍了表面吸附的微观机理研究进展 ,着重阐述了表面吸附的微观机理研究的理论基础、现代表面吸附的分析技术、现代理论研究方法 ,并指出了现代表面吸附研究的发展趋势。     

腐殖土对氨气的吸附动力学研究

氨是一种有强烈刺激性臭味且有毒的气体,室内空气中氨浓度限量值为0.2mg/m3.通过将一定量的氨水和腐殖土置于干燥器中,吸附一定时间,称量腐殖土的质量变化,利用表观一级、伪二级动力学模型和Elovich动力学模型,研究了腐殖土对氨气的吸附性能,及其吸附空气和水蒸气后,对吸氨性能的影响.结果表明,腐殖土对氨气的饱和吸附量...     

Penetration of Deposited Ag and Cu Overlayers Through Alkanethiol Self-Assembled Monolayers on Gold

The purpose of our research is to study the reactions, interactions, or penetration between vacuum deposited metals (M) and the organic functional end groups (OFGs) of self-assembled monolayers (SAMs) on Au films under controlled conditions. Metal/SAM/Au systems are models for understanding bonding at M/organic interfaces and the concomitant adhesion between the different materials. In broad terms, the M/OFGs form interacting interfaces (e.g., Cr/COOH or Cu/COOH) in which the deposit resides on top of the OFGs or weakly interacting interfaces through which the overlayer penetrates and resides at the SAM/gold interface. We present a review of XPS results from weakly interacting systems (Cu/CH₂OH, CU/CN, Ag/CH₃, Ag/COOH) and discuss in more depth the time-temperature dependence of the disappearance of the metal from the M/SAM interface following deposition using ISS on the Ag/CH₃ and Ag/COOH systems. XPS and ISS were used to characterize five alkanethiols terminated with CH₃, COOH(C—11 and C—16 chain lengths), CN and CH₂OH before and after depositing up to 1.0 nm Ag or Cu at ca. 10^-7 torr. XPS spectra indicate that no strong interaction occurs between the deposited Ag and the COOH organic functional group, although a stronger interaction is evident on a C—16 COOH, and a unidentate is formed for Cu on the CH₂OH. An interaction between Cu and CN is evident, and penetration into the SAM occurs to a greater extent than for Cu on CH₂OH. The Ag interaction with CH₃ is weak. ISS compositional depth profiles for Ag on COOH and CH₃, taken from 113 to 293 K, indicate that Ag remains on the surface of the C—11 COOH for up to 1 h after deposition, whereas Ag penetrates CH₃ in less than 5 min at 295 K. The time for Ag to penetrate into a C-16 COOH is several times longer than for the C—11 COOH and depends on the SAM temperature.     

Adsorption and Self-Assembly of Large Polycyclic Molecules on the Surfaces of TiO2 Single Crystals

Titanium dioxide is one of the most frequently studied metal oxides, and its (110) rutile surface serves as a prototypical model for the surface science of such materials. Recent studies have also shown that the (011) surface is relatively easy for preparation in ultra-high vacuum (UHV) and that both the (110) and (011) surfaces could be precisely characterized using scanning tunneling microscopy (STM). The supramolecular self-assembly of organic molecules on the surfaces of titanium dioxide plays an important role in nanofabrication, and it can control the formation and properties of nanostructures, leading to wide range of applications covering the fields of catalysis, coatings and fabrication of sensors and extends to the optoelectronic industry and medical usage. Although the majority of experiments and theoretical calculations are focused on the adsorption of relatively small organic species, in recent years, there has been increasing interest in the properties of larger molecules that have several aromatic rings in which functional units could also be observed. The purpose of this review is to summarize the achievements in the study of single polycyclic molecules and thin layers adsorbed onto the surfaces of single crystalline titanium dioxide over the past decade.     

空心四足体金纳米结构的吸收光谱研究

形貌对纳米结构材料的性质有很大的影响,所以制备各种新形貌在纳米材料领域也是很重要的一个方向。金是一种很有用的电子器件材料,它的很多形貌已经被制备出来,但是空心四足体金纳米结构材料到目前还很少被制备出来过。四足体纳米结构是指有一个中心,然后从中心出发有四支臂分别指向四个方向,犹如甲烷的分子结构。该篇论文报道了以氧化锌四足体为模板,HAuCl4为原料,抗坏血酸为还原剂,制备出空心四足体金纳米结构材料。通过对样品在各生长阶段的吸收光谱研究,确认及生长机理。     

苯酚在纤维上的吸附动力学研究

研究了自制的纤维对苯酚的吸附特性,测定了吸附动力学曲线,结果显示,纤维对水溶液中的苯酚有较快的吸附速度,达到吸附平衡的时间大约缩短了一倍。纤维吸附苯酚的实验数据与二级速率方程基本吻合,相关系数大于0.99,即吸附过程可以用二级速率方程进行描述。     

红霉素在大孔树脂上的吸附动力学研究

采用液膜及孔内扩散模型,模拟不同温度和不同红霉素(EM)初始浓度条件下,大孔吸附树脂HZ816及XAD16吸附红霉素的动态吸附曲线,并获得液膜传质及孔内扩散系数;考察了温度及溶质浓度对红霉素在两种树脂中吸附动力学的影响.结果表明,在实验范围内,红霉素在HZ816和XAD16两种树脂上的吸附平衡数据满足Langmuir吸附等温线方程,液膜及孔内扩散模型能较好地描述红霉素在两种树脂上的吸附动力学,同时,模型拟合得到的液膜传质系数随着温度的升高而增大,随着初始浓度的增大而增大,孔内扩散系数随着温度的升高而增大,随着初始浓度的增大而减小.     

活性炭对丁酮的吸附动力学研究

研究了2种活性炭（木质活性炭和煤质活性炭）对丁酮的吸附,重点考察了活性炭的吸附时间、吸附温度和丁酮载气流量对丁酮吸附的影响,并用准一级、准二级、Elovich和Bangham 4种动力学模型对活性炭在不同温度条件下对丁酮的吸附行为进行了动力学拟合,确定其动力学吸附模型。实验表明：不同的活性炭对丁酮的吸附过程不同;活性炭对丁酮的吸附是一个吸附和解吸同时存在的过程,当吸附速率和解吸速率相等时,该过程达到吸附平衡;随着吸附温度的升高,活性炭对丁酮的饱和吸附量逐渐降低,说明活性炭对丁酮的吸附过程为放热反应;丁酮载气流量对活性炭吸附丁酮达到饱和的时间以及吸附速率有影响,对AC-1的最终饱和吸附量影响显著,对AC-2的最终饱和吸附量没有显著影响。这2种活性炭吸附丁酮最适宜的吸附温度均为303 K,最佳的载气流量为400 mL/min。在不同温度下对活性炭吸附丁酮的过程进行动力学分析,发现Bangham方程计算得到的相关系数R²大于0.99,因此,活性炭对丁酮的吸附动力学方程符合Bangham动力学方程。     

甲基丙烯酸正丁酯（BMA）的聚合及动力学研究

研究了以4-氰基戊酸二硫代苯甲酸为链转移剂的甲基丙烯酸正丁酯（BMA）的RAFT聚合动力学,聚合物通过1HNMR和GPC来表征。制得的BMA均聚物可作为大分子链转移剂。     

氧气和氮气的吸附动力学行为测定

利用双柱定容容量法实时记录的数据研究了氮气和氧气在碳分子筛及13X分子筛上的吸附动力学行为,重点讨论了吸附时体系内的温度变化情况以及温度变化对于吸附和扩散行为的影响,指出建立数学模型时,温度变化的不可忽略性,同时获得了可用于非等温动力学模型计算的数据.     

氯霉素在活性炭上的吸附平衡与动力学

为去除水体中残留的氯霉素,采用生物相容性佳的活性炭作吸附剂,测定了25,30,35℃下氯霉素在自制活性炭上的吸附平衡与动力学,并与商用竹炭作对比。结果表明高比表面积活性炭是去除水体中残留氯霉素的高效吸附剂,活性炭的吸附容量随着吸附剂比表面积和孔容的增大而增大,但随温度从25,30到35℃升高而减小,自制高比表面积活性炭的吸附容量达到3种市售活性炭样品吸附容量的10倍以上;Freundlich吸附等温线方程可较好地描述氯霉素在活性炭上的吸附平衡,准二级方程是用来描述氯霉素在活性炭上吸附的合适动力学模型,并通过拟合得到了其动力学参数。随着温度的升高吸附容量逐渐减小。本研究为活性炭对水体中残留氯霉素的吸附处理提供了科学依据。     

功能纳米颗粒对木瓜蛋白酶吸附动力学及热力学研究

以磁性纳米颗粒(MNPs)为内核,外层包裹壳聚糖(CS),进一步键和α-酮戊二酸(α-KA),制备出一种新型的磁性离子交换色谱介质(α-KA-CS-MNPs).分别在277,298,310K的均衡条件下,批量法对木瓜蛋白酶进行等温吸附测定,实验所得数据分别用拟一级动力学模型和拟二级动力学模型进行分析.结果表明:拟二级动...     

阴离子交换树脂吸附辣椒碱的动力学研究

以辣椒树脂为原料,采用静态吸附法确定了201×7型阴离子交换树脂吸附辣椒碱的最优工艺和提取机理。通过可见分光光度法测定了辣椒碱的质量浓度,并绘制出了不同pH的吸附等温线,建立了离子交换吸附辣椒碱的动力学模型。实验结果表明:该树脂吸附辣椒碱的最优pH值为5.5,当pH5.0或pH6.0时,Langmuir方程能够更好地拟合该吸附过程;而当pH=5.0~6.0时,辣椒碱的吸附等温线更符合Freundlich方程。在pH=5.5、308.15K下,较高的辣椒树脂的质量浓度能显著提高离子交换速率,且初期(t30 min)800~1200r/min的搅拌速率有利于吸附过程。通过计算得出,树脂吸附辣椒碱模型的速率常数k0=2.11×10-3s-1、活化能Ea=12.6 k J/mol、反应级数为0.268,并利用Freundlich模型解析获得了最优pH值(5.5)下阴离子交换树脂吸附辣椒碱的动力学方程。     

铜的萃取动力学研究

本文用氯化三烷基甲铵(N_(263))—煤油体系作为有机相进行了从碱性氰化液中萃取铜的动力学研究。实验是在一恒界面池(Lewis cell)中进行的。实验结果表明:铜的萃取速率与两相的搅拌强度几乎无关;但正比于两相的接触界面积及萃取剂浓度;萃取反应过程的表观活化能为18.750kJ/mol。对系统进行理论分析的结果可知,铜的萃取反应过程为反应与扩散在水膜内并列进行的过程,其主要特征表现为包含水膜的界面反应。通过数据处理,建立了如下萃取动力学模型:用此模型计算所得结果与实验结果的平均偏差为4.9％。