Controlled fabrication of one-dimensional polymer nanostructures via metallogel template polymerization

A facile method is reported to controllably fabricate one dimensional(1D) polymer nanostructures via metallogel template polymerization.The metallogel was prepared through coordination interactions between silver ions and a ligand(L) bearing three pyridyl groups in tetrahydrofuran(THF).The diameters of the metallogel nanofibers could be tuned by the gel concentration(GC).Due to its high thermal stability and facility of removal,the metallogel was used as the template for radical polymerization of diacryolyl-2,6-diaminopyridine(DADAP) to form poly-diacryolyl-2,6-diaminopyridine(PDADAP) nanostructures.The gradually eroding of the templates by PDADAP provided us an effective way to fabricate various nanostructures of the polymer.We have demonstrated that different 1D nanostructures,including nanoribbons,nanotubes and nanowires,could be selectively fabricated by adjusting polymerization time,monomer concentration and GC.The rheological properties of the gel samples were tested by a rheometer.As prolonging the reaction time,more and more polymers were formed and the strength of the resulting polymer gels became higher and higher.The simple preparation process,easy controlled microstructures and adequate gel strength would make it a facile synthetic method for different 1D polymer nanosturctures.     

CA砂浆用乳化沥青助剂研究进展

助剂是CA砂浆用乳化沥青的重要组成部分,近年来随着我国高速铁路的快速发展,得到了广泛的应用。本文阐述了助剂对CA砂浆用乳化沥青及其制备CA砂浆的重要作用,详细介绍了CA砂浆用乳化沥青助剂的种类和分类、各种助剂对乳化沥青及其制备CA砂浆的性能影响及其作用机理,对CA砂浆用乳化沥青助剂的选择和协同作用进行了说明,并介绍了应用实例。另外,结合CA砂浆用乳化沥青的研究现状,提出了CA砂浆用乳化沥青助剂的未来发展方向。     

Rheological phase synthesis,characterization and magnetic property of a cobalt(II)diphosphonate

A new Co(II) diphosphonate compound, [Co(HEDPH₂)₂] (4,4′-bipyH₂)?·?H₂O (1) has been successfully obtained by a rheological phase reaction at 80°C. Single-crystal diffraction analysis shows a 1-D chain structure and the 1-D chains are assembled via hydrogen bonds into a 3-D supramolecular structure with channels. The protonated 4,4′-bipy molecules are encapsulated in the channels. Magnetic study shows 1 to exhibit antiferromagnetic interaction in the 1D Co--O--P--O--Co chain. Crystal data for 1: monoclinic, space group Cc, a?=?15.754(6)?Å, b?=?14.457(5)?Å, c?=?10.020(4)?Å, β?=?92.024(6)°, V?=?2280.7(14)?ų, Z?=?4.     

多壁碳纳米管填充高密度聚乙烯复合材料的导电性和动态流变行为

对多壁碳纳米管/高密度聚乙烯(MWNTs/HDPE)复合材料的导电性和动态流变行为进行了研究.发现复合材料的复数粘度η*随MWNTs含量φ的增大而增大.当φ>3wt%时,η*发生突变,在低ω区域表现为非牛顿流体行为,出现强烈的剪切变稀现象.将其称为流变渗流现象,对应的填料含量即渗流阈值φc.在动态储能模量(G′)、损耗模量(G″)与频率(ω)关系曲线上,随φ增加出现“第二平台”,第二平台的出现表明MWNTs与MWNTs之间、MWNTs与聚合物之间存在相互缠结形成网络的结构.同时发现,在tanδ~ω曲线上的低ω区出现凹谷.认为这是由于MWNTs长链结构在低ω时伸长/收缩,MWNTs与MWNTs相互接触形成了次级网络造成的.经过不同时间热处理后的ω扫描以及动态间扫描的结果证实了这种结构的存在.研究结果表明复合材料的流变渗流阈值与电渗流阈值相一致(均在3%~5%之间),动态流变行为与导电性存在一定的相关性.     

Effects of surfactant and salt concentrations on capillary flow and its entry flow for wormlike micelle solutions

Dynamic viscoelasticities and flow properties were measured for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) to examine the effects of surfactant (C _D) and salt (C _S). The relaxation time λ of a single mode Maxwell model was obtained, and the relationship between λ and free NaSal concentration was discussed. The relation between λ and was applied to the classification of flow curves, which were obtained using a capillary rheometer. In the flow curves, a shear rate jump occurred at low shear rates for the solutions with low , while bending was seen at high shear rates for all the flow curves. On the other hand, vortex growth at the salient corner in the entrance region of the capillary was also investigated. Four different flow patterns were identified: Newtonian-like flow (A), steady vortex flow (B), periodically oscillated flow (C), and perfectly unstable flow (D). In the steady vortex of the flow pattern B, the vortex length increased with increasing shear rate. In the flow patterns C and D, white turbidity was observed. Furthermore, the relation between λ and was also applied to the discussion on the development of the vortex.     

油酸钾对不同温度下阳离子瓜儿胶水溶液流变行为影响

实验测定了阳离子瓜儿胶水溶液的流变行为,讨论了油酸钾对其流变行为的影响．稳态剪切实验结果表明,加入油酸钾后,瓜儿胶溶液的零切黏度增加了近三个数量级,出现类似凝胶的性质．动态剪切实验结果表明,瓜儿胶溶液表观模量则随着油酸钾浓度的增加而增加,储存模量和损失模量对应的剪切模量随着油酸钾浓度的增加而减小．事实上,随着油酸钾浓度的增加,高分子交联在一起的聚集体数量逐渐减小,强度逐渐增加．温度的影响刚好相反,随着温度的升高,聚集体的数量逐渐增加,强度逐渐减小．     

Effect of ultrasound treatment on steady and dynamic shear properties of glucomannan based salep dispersions: optimization of amplitude level, sonication time and temperature using response surface methodology

The present study investigated effect of different amplitude levels (40, 70 and 100%), sonication temperatures (40, 50 and 60 °C) and exposure times (3, 7 and 11 min) on steady shear properties; apparent viscosity (η), shear stress (σ), consistency coefficient (K), flow behavior index (n) and dynamic shear properties; storage modulus (G′), loss modulus (G″), complex viscosity (η^∗), complex modulus (G^∗) and loss tangent (tan δ) values of glucomannan based salep solution (SS) and salep drink (SD) samples. In addition, the steady and dynamic shear properties were optimized using ridge analysis in terms of amplitude level, sonication temperature and exposure times levels. Increasing amplitude level and sonication time decreased considerably the η, σ, K, G′, G″ and η^∗ values of salep dispersions (SS and SD samples). However, sonication temperature did not have a remarkable effect on these properties.     

Acoustic velocity and attenuation coefficient of magnetorheological fluids under electromagnetic fields

Magnetorheological fluid (MRF) is a class of smart material whose acoustic properties can be varied rapidly and reversibly by the applied magnetic field. The MRF is proposed to be as actively sound barriers or acoustical metamaterial. This paper presents a theoretical model to study acoustic propagation in MRF under fields based on the Biot–Stoll model. The model considers the coupling interaction between ferro particle and base fluid. This paper investigated the acoustic velocity and attenuation of a commercial MRF dependence on the different parameters such as carrier fluid viscosity, permeability and intensity of magnetic field. The calculated results show that the attenuation is increased with small field strengths and independent on field strength when the magnetization begins to saturate.