偶联剂对钛酸钾晶须/双马来酰亚胺树脂摩擦磨损性能的影响

研究了不同偶联剂及钛酸钾晶须添加量对钛酸钾晶须 /双马来酰亚胺树脂复合材料的摩擦磨损性能的影响 .结果发现 ,钛酸钾晶须能明显提高复合材料的耐磨性 ,晶须的加入使材料的磨损率得到显著降低 ;钛酸钾晶须对材料具有一定的润滑性 ,添加晶须后材料的摩擦系数与树脂基体基本相当 ;偶联剂对复合材料的摩擦系数影响不大 ,但是合适的偶联剂对材料耐磨性的提高则具有明显的作用 .晶须添加量较低时 ,复合材料的磨损机理主要为较严重的粘着磨损 ,晶须添加量较高时 ,疲劳磨损占主导地位 .     

EXAMINATION OF THE SURFACE FREE ENERGY AND ACID-BASE PROPERTIES OF CELLULOSE BY THE COLUMN WICKING TECHNIQUE AND THE CRITICAL PACKING HEIGHT/DENSITY

INTRODUCTIONThe wicking technique has been used to determine the surface energy components of solids[1-7]. Generally, thereare two wicking processes in practice, i.e. thin layer wicking and column wicking. A comparison of the twowicking techniques made by van Oss et al.[2], shows that column wicking has a problem of showing differentpacking density due to some kinds of powder materials, i.e. clay can not give good repacking reproducibility[2].But thin layer wicking has a problem in sample…     

自然水体生物膜吸附Co,Ni和Cu的特征研究

研究了在自然水体中培养的生物膜吸附Co,Ni和Cu等3种重金属的热力学和动力学特征,并对生物膜吸附各重金属的热力学数据进行了非线性拟合.结果表明,3种重金属的吸附过程均符合Langmuir吸附等温曲线.在溶液中重金属浓度<0.5μmol/L时,生物膜对3种重金属元素的吸附能力顺序是Co>Cu>Ni;在重金属浓度>0.5μmol/L时,顺序是Cu>Co>Ni.对动力学数据进行非线性拟合的结果表明,生物膜对Co,Ni和Cu的吸附均在数小时内达到平衡,吸附过程符合Langmuir等动力学曲线.     

Block copolymers with Zwitterionic groups at specific sites: Synthesis and aggregation behavior in dilute solutions

Well‐defined linear diblock and triblock copolymers of styrene and isoprene, nearly symmetric in composition, with one or two sulfobetaine associogenic groups at the ends of the polymer chain or the junction points between blocks, were synthesized by anionic polymerization high‐vacuum techniques. The synthetic strategy used the combined initiation of polymerization with 3‐dimethylaminopropyllithium, living end‐capping with 1‐(4‐dimethylaminophenyl)‐1‐phenylethylene, and postpolymerization reaction with cyclopropanesultone. The association behavior of these macromolecules in dilute solutions in the nonpolar solvent CCl₄, good for both blocks, was studied by a number of methods, including static and dynamic light scattering and viscometry. The number and position of the associogenic groups dramatically influenced the association behavior of these model block copolymers. The end‐functionalized samples formed larger aggregates than the junction‐point‐functionalized ones. The difference was attributed to stronger excluded volume effects when the zwitterion group was located within the chain than when the group was at the chain end(s). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3791–3801, 2000     

表面修饰磷钼酸铵纳米微粒的合成及摩擦学行为研究

在醇-水体系中采用同阴离子共沉淀法合成了季铵盐修饰的(NH4)3PMo12O40纳米微粒,以TEM、 XRD、 FTIR、 TGA、 DSC等多种分析手段表征了这种纳米微粒的形貌和结构,在四球试验机上考察了它们的摩擦学性能.结果表明所合成的杂多化合物具有Keggin骨架结构,微粒粒径约20 nm,在有机溶剂中可良好分散,作为一类新型润滑油添加剂,具有良好的抗磨性能.     

Perfluorinated polymer surfaces comprising SF5-terminated long-chain perfluoroacrylate

A new perfluorinated acrylate monomer containing the SF₅(CF₂)₆-perfluorinated side chain was synthesized and polymerized into films. Bulk monomer characterization is consistent with the molecular structure based on FTIR, mass spectrometry and NMR analyses. The surface properties of polymer coatings were studied with aqueous wetting (contact angle) and X-ray photoelectron spectroscopy (XPS) methods. The surface composition is shown to be highly enriched in the terminal side chain SF₅-chemistry and exhibits properties consistent with a highly apolar, non-wetting perfluorinated polymer surface. Depth-dependent XPS studies using angular-resolved methods (ADXPS) confirmed a non-stoichiometric enrichment of sulfur and fluorine at the film ambient interface, consistent with a surface presence of the terminal SF₅-group and possibly film structural anisotropy in the surface zone. Time-of-flight (TOF) secondary ion mass spectrometry (SIMS) analysis supplements the XPS data by showing the presence of all expected SF₅-acrylate chemistry components in the outer 15 Å of the film surface.     

自组装DNA吸附取向的表面增强拉曼光谱法研究

对金基体上自组装寡聚核苷酸探针杂交前后进行电化学非现场及现场表面增强拉曼光谱(SERS)研究.非现场SERS研究表明,杂交形成的dsDNA在基体表面以A型和B型两种构象同时存在,杂交过程可能伴随DNA链在基体表面吸附取向的变化.根据现场SERS研究结果可知,ssDNA及dsDNA的大多数SERS谱带强度随电极电位正移而降低,尤其是归属于碱基A的两种面外振动模式,谱带变化更为明显.利用SERS表面选择定则判断出随着电极电位由负向正变化,ssDNA及dsDNA螺旋吸附取向由垂直吸附向平躺吸附于金基体表面变化.     

聚丙烯表面接枝PNIPAAm膜Ⅰ.光接枝反应和表面形态结构研究

以氧杂蒽酮或二苯甲酮为引发剂 ,通过紫外光引发表面接枝聚合的方法在聚丙烯薄膜表面引入了具有温度敏感特性的聚异丙基丙烯酰胺 (PNIPAAm)接枝聚合物层 .提高紫外光强度和接枝反应温度均有利于接枝率增大 ,而单体浓度对接枝率的影响存在最佳值 ,为 0 1 8mol L .在引发剂预浸渍引发接枝和休眠基引发接枝这两种方式中 ,后者能够实现更高的接枝率 .红外光谱 (FTIR)、X射线光电子能谱化学分析 (ESCA)和扫描电子显微镜 (SEM)等对接枝层组成的表征结果证实了接枝层的存在 .在不同温度下 ,接枝膜的FTIR谱图中酰胺I带和酰胺II带特征吸收峰发生位移 ,表明它具有温度敏感特性 .同时 ,SEM研究发现由于接枝膜的温度敏感特性而导致的球状表面形态结构     

Preparations of regioselectively methylated cellulose acetates and their 1H and 13C NMR spectroscopic analyses

Seven possible regioselectively methylated cellulose acetates (RS‐MCAs)—2,3,6‐tri‐O‐methyl cellulose acetate, 3,6‐di‐O‐methyl cellulose acetate, 2,6‐di‐O‐methyl cellulose acetate, 2,3‐di‐O‐methyl cellulose acetate, 6‐O‐methyl cellulose acetate, 3‐O‐methyl cellulose acetate, and 2‐O‐methyl cellulose acetate—were prepared for the first time from chemically synthesized cellulose derivatives obtained by cationic ring‐opening polymerization and then were analyzed by ¹H and ¹³C NMR spectroscopy. The chemical shifts of ring protons and carbons were influenced by substituent groups (methyl or acetyl) and clearly reflected the pattern of substituent distribution in anhydroglucose units. These data may conveniently be used for the determination of the substituent distribution of methyl cellulose. The synthesized RS‐MCAs also may be used for the elucidation of the structure–property relationship. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4167–4179, 2002     

A method for correcting the contact angle from the θ/2 method

The θ/2 method, a widely used technique on measuring the contact angle of a sessile drop, assumes that the drop profile is part of a sphere. However, the shape profile of a sessile drop is governed by the Young–Laplace equation and is different from a sphere, especially for drops with a large bound number (e.g. large volume or small surface tension). The spherical assumption, therefore, causes errors on evaluating the contact angles. The deviation of contact angle from the θ/2 method is evaluated from a theoretical calculation in this work. A simple means is given for correcting the measurement error. The corrected angle results from the drop volume, surface tension, liquid density and the contact angle from θ/2 method. An algorithm for finding the correct contact angle without knowing the density and surface tension is also given. At the end, two examples of pendant drops are given for the illustration.