Measurement of the rheological properties of polymer melts with annular rheometer

An annular die has been designed having a very thin gap distance between two coaxial cylinders. The die was then used to measure wall normal stresses along the longitudinal direction of polymer melts flowing through the thin annulus. The materials investigated were high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene. Also investigated were blends of polystyrene and polypropylene, and blends of polystyrene and high-density polyethylene The measurements of wall normal stresses were used to determine the rheological properties of the melts, namely, the melt viscosity from the slope of axial wall normal stress profiles and the melt elasticity from exit pressures. The interpretation of the experimental data was made possible by the fact that the narrow-gap annular die can be considered as a substitute for a thin slit die. It has been found that the results obtained in the present study are consistent with those reported earlier by the author, who at that time used both capillary and slit dies.     

Guerbet十四醇的合成与表征

以正庚醇为原料 ,通过Guerbet反应合成Guerbet十四醇 (2 戊基壬醇 ,C14 GA)。用IR、NMR和元素分析测定了C14 GA的结构 ,并研究了反应温度和用料比对其产率的影响。实验结果如下 :(1)在较优化的反应条件下 (正庚醇的总加入量为 1mol,在实验过程中 ,先加入 1/ 3mol庚醇和 1/ 4mol的KOH ,在 16 0℃下反应 2h ,然后再加入剩下的 2 / 3mol庚醇和 4g 5 %Pd -C催化剂 ,在 15 5℃下反应 6h)合成产物 ,其产率可达到 5 4 2 0 % ;(2 )所合成的产物与试图要得到的Guerbet十四醇 (2 戊基壬醇 ,C14 GA)含有相同的基团 (2×—CH3、10×—CH2 —、1×CH、1×—CH2 —O—和 1×—OH) ,而且 ,所合成的产物中 ,w (C) =79 0 6 % ,w (H ) =13 6 2 % ,与从Guerbet十四醇分子式计算的理论值w(C) =78 5 0 % ,w (H) =14 0 1%基本一致。可见所合成的产物正是Guerbet十四醇 (C14 GA)     

Industrial TiO2 based nacreous pigments as functional building materials: Photocatalytic removal of NO

In this paper, the photocatalytic activity of industrial titanium dioxide (TiO₂) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO₂ based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution.     

多降液管筛板塔的设计计算

简要介绍多降液管筛板塔的特点及塔板参数的设计计算方法。     

Substrate-mediated interactions and intermolecular forces between molecules adsorbed on surfaces

Adsorbate interactions and reactions on metal surfaces have been investigated using scanning tunneling microscopy. The manners in which adsorbates perturb the surface electronic structure in their vicinity are discussed. The effects these perturbations have on other molecules are shown to be important in overlayer growth. Interactions of molecules with surface steps are addressed, and each molecule's electron affinity is shown to dictate its adsorption sites at step edges. Standing waves emanating from steps are demonstrated to effect transient molecular adsorption up to 40 A away from the step edge. Halobenzene derivatives are used to demonstrate how the surface is important in aligning reactive intermediates.     

聚合物多元醇产品质量的影响因素与控制

从内在和外在质量两个方面，简要论述了影响聚合物多元醇(POP)产品质量的因素和控制产品质量的措施。     

Studies on multilayer film coextrusion III. The rheology of blown film coextrusion

Multilayer blown film coextrusion was studied, both experimentally and theoretically. For the experimental study, an annular die with a feed-port system was designed and multilayer blown films were produced by rotating the inner mandrel with a one horsepower variable-speed drive at speeds from nearly 2 to 6 rpm, and by inflating the tubular molten film with air. The die has 16 feed slots and melt pressure transducers are mounted along the axial direction of the outer wall of the annular flow channel. The transducers were used to determine the pressure gradient in the annular flow channel, which then permitted determination of the reduction in pressure drop when different combinations of two polymer systems were coextruded. Polymers used for b own film coextrusion were: (1) low-density polyethylene with ethylene-vinyl acetate; (2) low-density polyethylene with high-density polyethylene; (3) low-density polyethylene with polypropylene; (4) high-density polyethylene with ethylene-vinyl acetate. For the theoretical study, stratified helical flow was analyzed using a power-law non-Newtonian model. A computational procedure was developed to predict the number of layers, layer thickness, and the volumetric flow rate as functions of certain processing variables (namely, the pressure drop in the die, and the angular speed of rotation of the inner mandrel of the die) and the rheological parameters of the individual polymers concerned. Comparison was made of the theoretical prediction of volumetric flow rate with experimental ones. Some representative results are presented of the theoretically predicted axial and angular velocity distributions, shear stress profiles, and shear rate profiles.     

Precise localization of eye centers with multiple cues

Automatic detection and precise localization of human eye centers are the essential processes in photo related multimedia applications. Since eye center points are used as reference base points for further intelligent processing, precise eye center localization is very important. In face recognition the accuracy of localization of eye centers directly influences the identification accuracy. A multiple stage approach with multiple cues for detection and precise localization of eye centers is presented in this paper. Multiple scopes searching strategy is used for correctly extracting eye patch images from the background. Dedicated gradient based features and curvelet based features are constructed and used for comprehensively revealing the intensity distribution characteristics and the edge based texture around eye centers. A rebuilt score calculation mechanism is proposed and the rebuilt scores are used as a specific measurement index reflecting the matching accuracy. The final localizations of eye centers are determined with integrating the gradient based scores and curvelet based scores. The experiment results testing on public face datasets show that the localization accuracy of proposed approach outperforms the accuracy with other state of the art methods.     

Decentralized weighted control for a class of large‐scale systems with multi‐modes

In this paper, the control synthesis problem for a class of large‐scale systems with multi‐modes that are called large‐scale switched systems is addressed. By introducing the concept of decentralized switching signal and the relevant decentralized average dwell time, the asymptotic stability and weighted ?₂ gain performance are investigated. It should be noted that the decentralized switching covers general switching cases for large‐scale switched systems, namely, it admits both time‐dependent switching signal and arbitrary switching signal blended in the decentralized switching. Then, on the basis of the analysis results, the decentralized weighted control scheme including state feedback controller gains and switching signals is studied. Several design algorithms are proposed to meet different controller design problems. Finally, numerical examples are provided to illustrate theoretical findings within this paper. Copyright © 2013 John Wiley & Sons, Ltd.