Phase structure in the blend of atactic poly(vinyl alcohol) with atactic poly(vinyl alcohol‐block‐vinyl acetate)

An almost fully saponified atactic poly(vinyl alcohol) and an atactic poly(vinyl alcohol‐block‐vinyl acetate) of which degree of saponification is 89 mol % were blended by a solution casting method. The phase structure of the blend film was analyzed by optical microscopy, ¹³C‐NMR, and differential scanning calorimetry. The most remarkable structure of the blend was composed of cylindrical domains penetrating the film. The swelling behavior of the blend films was also investigated in the dimethylsulfoxide and water mixed solvents to find differences in solubility and diffusion behavior between the matrix and the domain. The cylindrical domains could be selectively dissolved away in water and the film became porous. We tried to change the size of the cylindrical domain with various film preparation conditions. This aimed to turn the film into the useful filter membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1807–1815, 2002     

水电站进水塔动水压力研究和探讨

基于理想流体,将进水塔简化成水中悬臂梁体系,推导了其受迫振动时的动力响应方程,给出了进水塔内外表面动水压力的解析表达式。与有限元法、水工抗震规范公式计算结果进行了对比,分析验证了该方法在进水塔结构上的适用性及准确性。结果表明:动水压力表达式与结构振型密切相关。该方法的动水压力曲线趋势与有限元方法相似,均在水面以下某深度处迅速变大及达到最大值后曲线值减小弯回,两者最终在塔体底部收于相近的值;最大值大于有限元法,其最大值处曲线折回明显,幅度较大。弹性模量和进水塔高度对动水压力的曲线形态和数值有重要影响。同时,输入激励荷载的频率对动水压力影响巨大,尤其频率与进水塔某阶频率相近时会导致动水压力的异常增大。该方法对分析进水塔动水压力具有参考价值。     

Conformation of polyacrylamide in aqueous solution with interactive additives and cosolvents

The viscosity of polyacrylamide (PAM) dilute aqueous solutions with NaCl, glucose, and SDS as additives was measured by Ubbelohde viscometry. There was linear relationship between reduced viscosity vs. PAM concentration in aqueous solutions. The Huggins constant k and intrinsic viscosity [η] were used to study the conformation of the polymer chains and the degree of polymer–solvent interaction. In addition, the viscosity of diluted PAM solutions in water with acetone, ethanol, DMF, and ethylene glycol as cosolvent was measured. It was found that the polymer chain conformation contracted as the acetone, ethanol, and DMF cosolvent composition ratio increased, but there was no distinguishing difference between water–ethylene glycol compositions. The solution properties of PAM were used to estimate the swelling properties of PAM gel in the same external conditions, as gel is formed by crosslinking of linear polymer. In good solvent the polymer chain should be expanded, and gel is expected to have large swelling ratio. In water cosolvent systems, when the linear polymer chain underwent coil–globule transition, PAM gel should have volume phase transition under corresponding external conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3122–3129, 2003     

Automated procedure to determine the thermodynamic stability of a material and the range of chemical potentials necessary for its formation relative to competing phases and compounds

We present a simple and fast algorithm to test the thermodynamic stability and determine the necessary chemical environment for the production of a multiternary material, relative to competing phases and compounds formed from the constituent elements. If the material is found to be stable, the region of stability, in terms of the constituent elemental chemical potentials, is determined from the intersection points of hypersurfaces in an (n−1)$(n-1)$-dimensional chemical potential space, where n$n$ is the number of atomic species in the material. The input required is the free energy of formation of the material itself, and that of all competing phases. Output consists of the result of the test of stability, the intersection points in the chemical potential space and the competing phase to which they relate, and, for two- and three-dimensional spaces, a file which may be used for visualization of the stability region. We specify the use of the program by applying it both to a ternary system and to a quaternary system. The algorithm automates essential analysis of the thermodynamic stability of a material. This analysis consists of a process which is lengthy for ternary materials, and becomes much more complicated when studying materials of four or more constituent elements, which have become of increased interest in recent years for technological applications such as energy harvesting and optoelectronics. The algorithm will therefore be of great benefit to the theoretical and computational study of such materials.     

Swelling activation energy of κ‐carrageenan in its gel state: A fluorescence study

A steady‐state fluorescence technique was employed to study the swelling of κ‐carrageenan gels at various temperatures. Pyranine was used as a fluorescence probe. The fluorescence intensity of pyranine was measured during the insitu swelling process of κ‐carrageenan gels. The fluorescence intensity increased exponentially as the swelling time increased. The increase in the fluorescence intensity was modeled with the Li–Tanaka equation, from which the swelling time constants and cooperative diffusion coefficients were determined. The swelling time constants decreased and the cooperative diffusion coefficients increased as the swelling temperature was increased. The swelling activation energies were measured to be 47.05 kJ/mol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

电化学界面处离子分布、静电势和ξ势的研究

Density functional theory is applied to predicting the structures and electrostatic potentials of planar electrochemical surfaces within the framework of the restricted primitive model where small ions are represented by charged hard spheres of equal diameter and the solvent is assumed to be a continuous dielectric medium. The hard-sphere contribution to the excess Helmholtz energy functional is evaluated using the modified fundamentalmeasure theory and the electrostatic contribution is obtained from the quadratic functional Taylor expansion using the second-order direct correlation function from the mean-spherical approximation. Numerical results for the ionic density profiles and the mean electrostatic potentials near a planar surface of various charge densities are in excellent agreement with molecular simulations. In contrast to the modified Gouy-Chapman theory, the present density functional theory correctly predicts the second layer formation and charge inversion of charged surfaces as observed in simulations and in experiments. The theory has also been tested with the zeta potentials of positively charged polystyrene particles in aqueous solutions of KBr. Good agreement is achieved between the calculated and experimental results.     

粒径对膨胀土无荷膨胀率的影响研究

为了研究粒径大小对重塑土无荷膨胀率试验结果的影响,在符合现有规范的试验条件下,将某地基泥岩碾碎成1~2 mm、0.1~1 mm、0.1 mm的三种不同粒径,进行不同比例组合搭配的重塑土无荷膨胀率试验。试验结果表明:不同粒径大小的膨胀土样的无荷膨胀率试验结果有很大差异,并且不同粒径组合下的无荷膨胀率试验结果呈正态分布趋势,且峰值处的无荷膨胀率值为该重塑土稳定、可靠的无荷膨胀率值,无荷膨胀率试验结果接近峰值处无荷膨胀率值的粒径级配为该重塑土的最佳级配。经过分析得到使重塑土无荷膨胀率结果稳定、可靠的粒径级配是1~2 mm、0.1~1 mm、0.1 mm的土粒质量比为0∶100∶0,即使重塑土无荷膨胀率试验结果稳定可靠的粒径范围为0.1~1 mm。在该粒径范围内的重塑土无荷膨胀率试验结果最为真实、准确。     

Effect of the nature and degree of crosslinking on the Rose Bengal uptake by DVB‐, NNMBA‐, HDODA‐, and TTEGDA‐crosslinked aminopolyacrylamides

Polyacrylamides with 2–20 mol % divinyl benzene (DVB), N,N′‐methylene‐bisacrylamide (NNMBA), 1,6‐hexanediol diacrylate (HDODA), and tetraethyleneglycol diacrylate (TTEGDA) crosslinking and without crosslinking were prepared by free radical solution polymerization. Amino functions were incorporated into these polymers by transamidation with excess ethylenediamine. The dye uptake of nonprotonated and protonated aminopolyacrylamides was followed by batch equilibration method towards Rose Bengal (RB), Methyl Orange (MO), Methyl Red (MR), and Methylene Blue (MB). RB uptake by the polyacrylamide‐supported systems is higher than other dyes. Generally the dye uptake by the protonated systems is higher than the nonprotonated systems. To optimize the conditions of dye uptake, the effect of the concentration of RB solutions, temperature, and pH were followed. Kinetic studies showed that the uptake of RB by both nonprotonated and protonated crosslinked aminopolyacrylamides is a phase boundary process followed by three‐dimensional diffusion. The extent of RB uptake by the various systems depends on the nature and degree of crosslinking, and the relative rigidity/flexibility ofthe polyacrylamide support. Thus, the dye uptake followed the order: linear > NNMBA‐ > DVB‐ > TTEGDA‐ > HDODA‐crosslinked system. The dye uptake followed the same trend as the variation of amino capacity with degree of crosslinking in the respective crosslinked system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

三元乙丙橡胶－甲基丙烯酸甲酯溶胀机械接枝共聚研究

采用直接溶胀法，在叶片混合器中以不同条件制备了三元乙丙橡胶－甲基丙烯酸甲酯接枝共聚物。通过动态力学粘弹谱表征，该接枝共聚物具有稳定的双相体系相态。在适宜条件下，可以制得较好综合性能的接枝共聚物。     

电沉积锌钴磷合金时阴极行为的研究

用动电位扫描法研究了在氯化物镀液中电沉积Ｚｎ－Ｃｏ－Ｐ合金时的阴极行为。认为在镀液中加入配体柠檬酸钠可以提高阴极极化。加入次磷酸钠有利于合金镀层的形成。