Synthesis and Characterization of Polystyrene-b-Poly(4-vinyl pyridine) Block Copolymers by Atom Transfer Radical Polymerization

We aimed at the synthesis of well-define PS-b-P4VP by using atom transfer radical polymerization in two-step process. First, polystyrenes with benzyl bromide end group (PS-Br; by ATRP) were prepared as macroinitiator for the next ATRP of 4-vinyl pyridine and characterized these polymers from ¹H-NMR and MALDI-TOF. Comparing with MALDI-TOF-MS, ¹H-NMR and GPC analyses, this indicates that the formation of the block copolymer can be observed. During the polymerizations, molecular weight distribution and kinetics have been evaluated from GPC traces and ¹H-NMR analyses. We further characterized the thermal properties of these block polymers by DSC and TGA. DSC measurement on the PS-b-P4VP block copolymers exhibited two glass transitions, indicating that the resulting block copolymers are phase separated. Two maxima differential peaks were observed on the TGA trace for the PS-b-P4VP block copolymers might be assigned to the decomposition of the P4VP blocks at 380 ^○C and the PS blocks at higher temperature.     

釉应力光学测定法的应用

根据受应力作用的玻璃体在正交偏光下产生双折射的性质提出的釉应力测定法，能简便、快速地测定油层应力的大小。不失为评价陶瓷坯釉结合的一种有效方法。     

Miscibility and hydrogen bonding in blends of poly(vinyl acetate) with phenolic resin

The miscibility of phenolic resin and poly(vinyl acetate) (PVAc) blends was investigated by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and solid state ¹³C nuclear magnetic resonance (NMR). This blend displays single glass transition temperature (T_g) over entire compositions indicating that this blend system is miscible in the amorphous phase due to the formation of hydrogen bonding between hydroxyl groups of phenolic resin and carbonyl groups of PVAc. Quantitative measurements on fraction of hydrogen-bonded carbonyl group using both ¹³C solid-state NMR and FT-IR analyses result in good agreement between these two spectroscopic techniques. According to the proton spin-lattice relaxation time in the rotating frame (T_1ρ^H), the phenolic/PVAc blend is intimately mixed on a scale less than 2-3 nm. Furthermore, the inter-association equilibrium constant and its related enthalpy of phenolic/PVAc blends were determined as a function of temperatures by infrared spectra based on the Painter-Coleman association model.     

二氧化硫在钒催化剂上氧化动力学的研究——Ⅰ.永利钒催化剂的动力学方程式

<正>二氧化硫在钒催化剂上的氧化动力学问题,已经有很多人进行过研究。不过异相催化过程一般是比较复杂的,影响催化速度的因素除了催化剂本身的化学及表面性质,反应的温度,反应物与生成物的浓度之外,还有反应物或生成物在催化剂表面上的吸附或解吸速度,到达或离开催化剂表面上的物质传递过程的速度等复杂性。     

Biocatalytic production of 10-hydroxystearic acid, 10-ketostearic acid, and their primary fatty amides

The objective of this study was to develop scaleup bioprocesses for producing 10-hydroxystearic acid (10-HSA) and 10-ketostearic acid (10-KSA) as well as their primary amides for potential new uses. A reactor process was examined to obtain the mono-oxygenated FA using Sphingobacterium thalpophilum (NRRL B-14797) and Bacillus sphaericus (NRRL NRS-732), which solely produce 10-HSA and 10-KSA, respectively, from technical-grade oleic acid. By using an 8-h-old B-14797 culture grown in a manganese-containing WF6 medium, pH 7.3, at 28°C under 350 rpm agitation and 0–50% dissolved oxygen concentrations provided by a controlled sparger aeration, the production of 10-HSA reached 7 g/L with a 40% yield in 4 d. In using a 12-h-old NRS-732 culture grown in a pyruvate-containing PF6 medium, pH 6.5, at 30°C under 750 rpm agitation without any sparger aeration during the conversion reaction, 10-KSA production reached 7.9 g/L with a yield of more than 54% in 72 h. The scaleup reactor process provided crystalline 10-HSA and 10-KSA for producting new primary amides via a lipase-catalyzed amidation reaction with yields of 94 and 92%, respectively. The primary amides of 10-HSA and 10-KSA displayed m.p of 115 and 120°C, respectively.     

Nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate)/clay nanocomposites

The nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate) (PEGMA) and PEGMA/clay were studied by differential scanning calorimeter, at various cooling rates. Avrami model modified by Jeziorny, Ozawa mode and Liu model could successfully describe the nonisothermal crystallization process. Augis–Bennett model, Kissinger model, Takhor model, and Ziabicki model were used to evaluate the activation energy of both samples. It was found that the activation energy of PEGMA/clay nanocomposite was higher than that of neat PEGMA. Experimental results also indicated that the addition of modified clay might retard the overall nonisothermal crystallization process of PEGMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1335–1343, 2006     

Investigating the need of a pre-concentrator column for acetic acid dehydration system via heterogeneous azeotropic distillation

In our previous study [Chien, I.L., Zeng, K.L., Chao, H.Y., Liu, J.H. (2004). Design and control of acetic acid dehydration system via heterogeneous azeotropic distillation. Chemical Engineering Science 59(21), 4547-4567.], an acetic acid dehydration system has been designed. The suitable entrainer selected for that system is iso-butyl acetate. Design and control of the system has been studied in detail to maintain high-purity bottom acetic acid concentration and also keep a small acetic acid loss through top aqueous draw. In that previous study, the feed composition is assumed to contain equal molar of acetic acid and water. However, in a typical waste acid recovery application, the above assumption may be too rich in acetic acid. In this paper, a feed stream containing 80 mol% water and 20 mol% of acetic acid is investigated. Several design alternatives can be deduced including one commonly used in industry by adding a pre-concentrator column in the upstream of a heterogeneous azeotropic distillation column. The necessity of this pre-concentrator column from design and control view points will be thoroughly investigated in this paper. The final recommended process design is a tradeoff between total annual cost (TAC) and operability of the system. The recommended design is a single heterogeneous azeotropic distillation column with aqueous reflux stream. Very wide feed composition and flow rate changes can be handled by this design with proper choice of the overall control strategy.     

Methods for quantifying metamerism. Part 1ndashVisual assessment

This work forms part of the Society of Dyers and Colourists' CMC Working Group 1 project on metamerism and colour constancy. The aim of the project is to derive reliable indices for predicting metamerism and colour constancy. Some 76 metamers were prepared by dyeing wool with acid dyes. Two experiments were conducted to quantify the degree of metamerism using a grey-scale method. In the first experiment each metamer's colour difference was assessed against a grey scale by a panel of observers under seven light sources. The second experiment was carried out under three sources: D₆₅, A and TL₈₄. Each observer assessed not only the total colour difference as in the first experiment but also the separate lightness, chroma, and hue components. Observer variations were investigated in terms of observer precision, and within-and between-observer errors. Cross-over wavelengths for each metamer were also examined. It was found that intersections tend to converge on three wavelengths for almost all metamers used here, in agreement with previous findings.     

三氧化二铝纳米流体粘滞度的实验研究

使用直接混合法制备三氧化二铝纳米流体,探讨三氧化二铝纳米流体在不同浓度(0%,0.1%,0.5%,1.0%,ω)和温度(10～40 ℃)下粘滞度的变化规律.使用Brookfield DVⅢ 流变仪进行测量,发现添加入纳米粒子于去离子水中所得三氧化二铝纳米流体符合牛顿粘性定律,为牛顿流体.任一纳米流体的粘滞系数随着温度的上升而下降,呈反比关系,而随浓度上升而增加,呈正比关系,在温度40 ℃和浓度为1.0%(ω)时粘滞度增大比率可达到25.2%.而压降在任何浓度的纳米流体均与去离子水相差大约5 MPa,显示加入纳米粒子对压降的影响不明显.当温度愈高时,压降也随着降低,代表未来可将纳米流体应用层面推向更高温的领域.     

Fabrication of Patterned Inverse Opal Structure Through Physical Confinement Assembly and Selective Electrochemical Deposition

We develop a chemical modification-free process for fabrication of patterned photonic crystals (PhCs) of inverse opal structure. This process, involving photolithography, colloidal assembly, and electrochemical deposition, is potentially applicable for fabrication of practical optical devices. Polystyrene (PS) spheres were self-assembled onto pre-patterned substrates to serve as the sacrificial template. This template was then converted into a patterned inverse opal structure with selective electrochemical deposition. The thickness of the inverse opal structure can be easily controlled by adjusting the time of electrodeposition. We demonstrated the process with fabrication of a T-shape structure surrounded by an inverse opal structure of titania. Titania was chosen here as a representative demonstration material, and the process can be readily applied to other materials of desired characteristics.