油酸/PS/TiO_2复合纳米微球对液体石蜡抗磨性能的影响研究

采用种子乳液聚合法制备了油酸 / PS/ Ti O2 复合纳米微球 ,在四球摩擦磨损试验机上考察了油酸 / PS/ Ti O2 复合纳米微球添加剂对液体石蜡抗磨性能的影响 ,采用 X射线光电子能谱分析了钢球磨斑表面边界膜元素的组成及化学状态 .结果表明 ,油酸 / PS/ Ti O2 复合微球作为润滑油添加剂具有良好的抗磨性能 ,能显著提高基础油的失效载荷 .表面分析结果表明 ,复合纳米微球的抗磨作用取决于其摩擦化学反应所生成的含有 Ti O2 及部分添加剂分解产物的复合膜 .     

液相色谱-质谱法分析季戊四醇油酸酯

提出了高效液相色谱-质谱法测定单、双季戊四醇油酸酯中单酯、双酯、三酯和四酯的含量。样品经正己烷-异丙醇(9+1)溶剂溶解后,以Lichrospher Si100-5色谱柱(4.6mm×250mm,5μm)为分离柱,以不同体积比的正己烷和异丙醇混合溶液为流动相梯度淋洗。采用总离子流图的峰面积归一化法对单、双季戊四醇油酸酯中单酯、双酯、三酯和四酯的含量进行定量,用质谱法做鉴别。     

Liquid-phase hydrogenation of methyl oleate on a Ni/α-Al2O3 catalyst: A study based on kinetic models describing extreme and intermediate adsorption regimes

The kinetics of the hydrogenation of methyl oleate on a Ni/α-Al₂O₃ catalyst was studied in the absence of mass-transport limitation, at 398 ≤ T ≤ 443 K and 3.7 ≤ P_H2 ≤ 6.5 bar. The kinetic modeling was performed on the basis of elementary step mechanisms involving different regimes of competition between hydrogen and methyl oleate. Admitting a distinction between occupied-sites and covered-sites by the large molecule of methyl oleate, a rigorous proposal was made to link the seemingly separate kinetic models corresponding to the extreme modes of competitive and non-competitive adsorption, without having to draw the common distinction between two types of surface sites. General rate equations were formulated without expressing opinion a priori on whether the adsorption regime is competitive or non-competitive. Then, typical LHHW rate equations for both extreme adsorption regimes were straightforwardly derived as special cases. Statistical results demonstrated the inadequacy of the models approaching non-competitive adsorption to describe the experimental data but results did not allow a definite discrimination between rival models with competitive and semi-competitive adsorption. A mechanistic model featuring dissociative adsorption of hydrogen, molecule of methyl oleate interacting with a single atom of Ni, and second insertion of hydrogen as RDS, proved to be the best candidate to describe the experimental data satisfactorily with physically reasonable parameters. As a distinctive feature, the model considering semi-competitive adsorption gave additional indication that the adsorbed molecule of methyl oleate could cover up to seven surface sites. From this finding, the semi-competitive model seems to be more realistic than the competitive one.     

Effect of Potassium Oleate on Rheological Behavior of Cationic Guar in Aqueous Solution with Varying Temperatures

The rheology of the cationic guar (CG) solution was measured and the effects of potassium oleate (KOA) upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc (corresponding to either storage modulus G′ or loss modulus G″ at the frequency w_c where G′ equals G″) for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time τ_app (=1/w_c) increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfactant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.     

Effects of l-arginine on aggregates of fatty-acid/potassium soap in the aqueous media

In the present study, we investigated the effects of l-arginine on aggregates of fatty acid/fatty soap in the aqueous media as a function of pH, by means of hydrogen ion titration, viscoelastic measurement, cryo-transmission electron microscopy and phase contrast microscopy. We found out that l-arginine effectively inhibits the oil droplet growth of oleic acid or octanoic acid. The effect is explained in terms of the adsorption of arginine at the microscopic drop surface, or at the oil/water microinterface through the hydrophobic effect assisted by the hydrogen bonds between carboxyl group of fatty acid and carboxylate of arginine. As to the crystallization of lauric acid at temperatures below the melting point of the hydrocarbon chain, arginine is not effective. In addition, we also found out that the strong binding of arginine cation to anionic oleate micells induces the dominant micellar growth. l-arginine has been used in many refolding systems to suppress protein aggregation. These effects of l-arginine on the aggregates of fatty acid/fatty soap in the aqueous media observed in the present study is expected to form a basis to the specific function displayed in the protein refolding.     

In situ preparation of hydrophobic CaCO3 in the presence of sodium oleate

Hydrophobic CaCO₃ particles were directly prepared via carbonation of Ca(OH)₂ slurry in the presence of sodium oleate at room temperature. Sodium oleate was used to modify the surface property of CaCO₃ particles. The measurement of relative contact angle and active ratio indicated that CaCO₃ samples were hydrophobic. DTG, FT-IR and TEM analysis of the obtained product indicated that the hydrophobic property was attributed to the deposition of calcium oleate, produced in the reaction mixture, onto the surface of calcium carbonate particles. They were covered on the CaCO₃ crystals surface and modified their surface property; at the same time they own CC bonds and could be polymerized or copolymerized later to give a polymeric monolayer.     

Synthesis and property of poly(trimethylolpropane triacrylate)/Al nanocomposite particle by in situ solution polymerization

In order to improve its dispersibility and preserve its activity, nano-aluminum was encapsulated with poly(trimethylolpropane triacrylate) (PTMPTA) by in situ solution polymerization. The affecting factors of the conversion of monomer (CM), percentage of grafting (PG) and grafting efficiency (GE) were systematically studied. It was found that nano-aluminum had been evenly encapsulated with a layer of PTMPTA through chemical bond. And PTMPTA/Al nanocomposite particle with core-shell structure had been successfully synthesized. Compared to that of nano-aluminum, the dispersibility, corrosion resistance, thermal stability, especially the activity preservation (when it was used as additive in solid rocket propellants) of composite particle had been markedly improved.     

Immobilization of cholesterol esterase and cholesterol oxidase onto sol-gel films for application to cholesterol biosensor

Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) have been covalently immobilized onto tetraethylorthosilicate (TEOS) sol-gel films. The tetraethylorthosilicate sol-gel/ChEt/ChOx enzyme films thus prepared have been characterized using scanning electron microscopic (SEM), UV-vis spectroscopic, Fourier-transform-infrared (FTIR) spectroscopic and amperometric techniques, respectively. The results of photometric measurements carried out on tetraethylorthosilicate sol-gel/ChEt/ChOx reveal thermal stability up to 55 °C, response time as 180 s, linearity up to 780 mg dL⁻¹ (12 mM), shelf life of 1 month, detection limit of 12 mg dL⁻¹ and sensitivity as 5.4 × 10⁻⁵ Abs. mg⁻¹ dL⁻¹.     

Biosensor for total cholesterol estimation using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane self-assembled monolayer

Cholesterol oxidase (ChOx), cholesterol esterase (ChEt), and horseradish peroxidase (HRP) have been co-immobilized covalently on a self-assembled monolayer (SAM) of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTS) deposited on an indium–tin–oxide (ITO) glass surface. These enzyme-modified (ChOx-ChEt-HRP/AEAPTS/ITO) biosensing electrodes have been used to estimate cholesteryl oleate from 10 to 500 mg dL⁻¹. The sensitivity, K _m value, and shelf-life of these ChEt-ChOx-HRP/AEAPTS/ITO biosensing electrodes have been found to be 124 nA mg⁻¹ dL, 95.098 mg dL⁻¹ (1.46 mmol L⁻¹), and ten weeks, respectively. The ChEt-ChOx-HRP/AEAPTS/ITO bio-electrodes have been used to estimate total cholesterol in serum samples. Figure Covalent immobilization of enzymes onto AEAPTS/ITO surface using EDC/NHS chemistry Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

树枝状多氨基大分子环氧树脂固化剂的研究

三羟甲基丙烷三丙烯酸酯（TMPTA）和乙二胺（EDA）进行Michael加成反应,合成了外围带多个活泼氢原子的树枝状大分子G1.0（NH2）。最佳合成条件为：n(EDA)=1:12,甲醇作催化剂,50℃反应24h,产率97.01%,G1.0(NH2)的质量分数为96.02%用IR、NMR和元素分析表征G1.0（NH2）的结构。与EDA/环氧树脂体系相比,G1.0（NH2）/环氧树脂体系适用期较长、凝胶时间和快速度固化。G1.0（NH2）在固化过程中分两阶段逐渐放热,且总放热量小于EDA固化剂体系,TGA分析表明两种体系固化产物热稳定性相似。